Foreword

Lasers in Medicine and Surgery

The quest for possible applications of the very high energy densities

achieved using coherent light to problems in clinical medicine and surgery
began nearly concurrent with the invention of the laser. In the 1960s, pio-
neering laser biophysics outlined light–tissue and light–substance interac-
tions. In the 1970s, clinical trials applied lasers to incision, excision, and
ablation procedures that were not being well served by sharp steel or electro-
surgery. It is from this process that there evolved indications for ‘‘the tool in
search of a need.’’

In the 1980s, industrial lasers proliferated, and there was universal adop-

tion of ‘‘laser’’ as a noun. The concept of powerful light was also integrated
as an element of popular culture and produced word-associated perceptions
of unique proprieties and high capability. During this time, clinical and
surgical applications continued to expand. In addition, the clinical pharma-
cology and light delivery for the initial use of light-activated, photoreactive
molecules as selective tumor intoxicants also emerged.

In the 1990s, great improvements were noted in machine reliability,

economies of purchase, greater capability and ﬂexibility of light delivery and
targeting accessories, and better availability of training. The lowered costs
for purchasing equipment facilitated the mainstream use of laser techniques
and good momentum toward the use of lasers in the veterinary profession
was seen.

As an early user of the carbon dioxide laser in small animal surgery

(1970s), it is gratifying to see wider clinical scope and use. It is now fair
to say that various surgical lasers have extended the operative precision,
range, and morbidity reduction in small animal surgery. Equine upper air-
way surgery has also been revolutionized, and there are certainly many
applications yet to be developed.

As you enjoy the articles that follow, please know that the future is more

exciting and diverse than the present. For example, future applications for
medical and surgical therapy in animals may include practical tunable lasers
to vary light wavelength output; improved endoscopic and endovascular
procedures; light–substance ablations beyond lithotripsy; subcellular and

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genetic surgery; and light interactions with yet to be developed photoreac-
tive and photointeractive drugs.

Stephen W. Crane, DVM

2425 East Oquendo Road

Las Vegas, NV 89120-2406, USA

E-mail address: steve@westernveterinary.org

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S.W. Crane / Vet Clin Small Anim 32 (2002) xi–xii

Preface

Lasers in Medicine and Surgery

Guest Editor

The use of lasers in veterinary medicine is not new. In fact, over the past

15 years, small groups of veterinary clinical scientists at various universities
and veterinary practices have periodically met to discuss the use of surgical
lasers in our profession. The cost of laser technology was an obvious limita-
tion and prevented widespread use in general practice. In addition, lasers
available for use in veterinary medicine were usually obtained from the sec-
ondary human medical market, were quite cumbersome, and required signif-
icant maintenance to ensure safe and reliable use. Two important factors
opened the door for clinical use of lasers in veterinary medicine: (1) techno-
logic advancements in laser engineering, which resulted in smaller, more reli-
able devices; and (2) recognition by laser manufacturers that veterinary
medicine is a viable market for technology transfer. Even with increased
availability, however, education should be the deciding factor on whether
surgical lasers should be integrated into a clinical program or practice. To
successfully move into this new and exciting modality of laser surgery, it
is essential that ‘‘we learn before we burn.’’ A cavalier attitude toward laser
surgery can be disastrous for both the operator and the patient.

Although learning to use a surgical laser is not diﬃcult, there is a learning

curve that must be considered before becoming a competent and knowledge-
able laser surgeon. Educational venues oﬀered at regional and national
veterinary meetings usually provide objective exposure to the technology
and provide the ‘‘beginning’’ of the learning process. In addition, most con-
ventions provide an exhibit hall where diﬀerent laser devices can be viewed
and investigated. Some manufacturers also provide sponsored educational

Kenneth E. Bartels DVM, MS

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venues with both didactic and ‘‘hands-on’’ workshops where beginning and
advanced laser users can work with colleagues and technical representatives
from those companies. Finally, a few organized groups oﬀer both scientiﬁc
and practical knowledge that can be shared during annual meetings (Amer-
ican Society of Laser Medicine and Surgery; International Society of Optical
Engineers—BiOs; Veterinary Surgical Laser Society). It is imperative that, as
experience using lasers increases, so will the contributions to peer-reviewed
literature. Promotional materials and articles in magazines certainly serve
their purpose; however, universal acceptance of lasers in veterinary medicine
by the entire profession will not occur until their use meets appropriate
criteria of scientiﬁc review.

In considering any new technology, it is important to ﬁrst understand the

fundamentals. In giving lectures to both students and colleagues, I am often
asked to shorten the theoretical and basic information and get to the ‘‘prac-
tical’’ stuﬀ that is important for passing examinations or for making money.
As Dr. Fuller Albright, the preeminent clinical and investigative endocrinol-
ogist, said in his article ‘‘Good Doctors and Bad’’:

‘‘By ÔpracticalÕ is usually meant ÔtherapeuticÕ; by ÔtheoreticalÕ is usually meant
Ô

fundamental.Õ The author has no patience with such a philosophy. One

cannot possibly practice good medicine and not understand the fundamen-
tals underlying therapy. Few if any rules for therapy are more than 90%
correct. If one does not understand the fundamentals, one does more harm
in 10% of the instances to which the rules do not apply than one does good
in the 90% to which they do apply. The same policy carries over to medical
education. There are those who advocate medical schools turning out prac-
tical physicians rather than Ôtheorists.Õ But they end by turning out a poorer
grade of doctor. As with eggs, there is no such thing as a poor doctor; doc-
tors are either good or bad.’’ [1]

To that end, this issue of Veterinary Clinics of North America: Small Ani-

mal Practice is an eﬀort to assemble a number of experts from both acade-
mia and clinical practice. Discussions range from the ‘‘fundamentals’’ to
‘‘practical’’ applications where authors have tried to discuss objectively the
use of lasers in veterinary medicine. Although the articles are directed pri-
marily to small animal practitioners, most of the information is fundamental
knowledge that can be appreciated by every veterinarian interested in this
exciting technology. From the basics of laser–tissue interaction and safety
to advanced clinical applications, an attempt was made to discuss the surgi-
cal lasers commonly used in practices today. Although some article authors
place signiﬁcance on use of one particular manufacturerÕs laser, it should be
realized that information provided is of a general nature. Procedures and
guidelines reviewed should apply to other devices of the same wavelength,
taking into account diﬀerences in energy and delivery parameters as well
as tissue interaction.

Finally, it is crucial that objective clinical application of lasers—both eco-

nomically and technologically—blend smoothly into veterinary medicine. Our

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K.E. Bartels / Vet Clin Small Anim 32 (2002) xiii–xv

goal with this issue has been to use both the science and art of veterinary med-
icine to describe how this has been done in the past few years. More impor-
tantly, we hope it will serve as a reference for the future!

My heartfelt thanks goes to the contributing authors who took the time

to make this issue complete, from the basics to the practical. I am also very
grateful to my wife, Jan, and my daughter, Elizabeth, for their patience, and
to my parents, who would have enjoyed seeing this issue in print.

Kenneth E. Bartels, DVM, MS
Department of Clinical Sciences

College of Veterinary Medicine

Oklahoma State University

Stillwater, OK 74078, USA

E-mail address: kebart@okstate.edu

Reference

[1] Albright F. Good doctors and bad. In: Beason RB, McDermott W, editors. Cecil-Loeb

textbook of medicine, 11th edition. Philadelphia: W.B. Saunders; 1963. p. 1341.

K.E. Bartels / Vet Clin Small Anim 32 (2002) xiii–xv

Lasers in veterinary medicine—where

have we been, and where are we going?

Kenneth E. Bartels, DVM, MS

Department of Veterinary Clinical Sciences, College of Veterinary Medicine,

Oklahoma State University, Stillwater, Oklahoma 74078, USA

The principles necessary for the concept of laser development were re-

ported as early as the nineteenth century with Bohr’s theory of optical reso-
nance. In 1917, Einstein proposed the concept of stimulated light emission.
Finally in 1960, Theodore Maiman developed the ﬁrst operational laser,
which was a pulsed ruby laser [1]. His work was based on Albert Einstein’s
explanation of stimulated emission of radiation, coupled with Townes’
and Schawlow’s 1958 work with optical masers [2]. Since then, much of the
progress in laser technology followed weapons research or commercial
applications in the communication and manufacturing industries. When the
‘‘Cold War’’ ended, increased initiatives by laser manufacturers, formerly
dedicated to military applications, provided a tremendous stimulus for
advancements in both industrial and medical laser technology.

Since its medical use began, the laser has been and is still considered by

many to be ‘‘a tool in search of an application.’’ Medical lasers of the past
were cumbersome, expensive, and diﬃcult to maintain. As biomedical laser
technology merges with the economic reality of medicine, however, innova-
tions and improvements in existing devices and development of new concepts
will continue. New ideas and modiﬁcations of current laser technology will
be essential to keep pace with changes in veterinary medicine. Relatively
recent technologic introductions, including the development of diode lasers
and ﬁberoptic delivery systems, as well as portable, aﬀordable, and reliable
carbon dioxide (CO

) lasers, are now available to veterinarians. Other types

of lasers with diﬀerent wavelengths and delivery parameters are also avail-
able, depending on clinical requirements. The vernacular or perceived con-
cept of ‘‘using laser,’’ implying there is one perfect wavelength, or only one

Vet Clin Small Anim 32 (2002) 495–515

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all-purpose system, is unacceptable. Because of speciﬁc properties, certain
lasers may be uniquely suited to a given clinical task compared with other
lasers or energy modalities.

The use of lasers in veterinary medicine includes both nonsurgical and

surgical applications. Surgical applications involve direct physical alteration
or removal of target tissue. Laser surgical treatments are referred to as photo-
thermal or photomechanical applications. Examples of commonly used
photothermal applications include laser hyperthermia and laser tissue vapor-
ization. An example of a photomechanical application is laser lithotripsy,
in which laser light creates an acoustical shock wave used to break down
urologic or biliary calculi. Nonsurgical applications include such tech-
niques as laser biostimulation, diagnostic use including optical biopsy, and
photodynamic (PDT) therapy. The potential for future development of
additional applications, especially for noninvasive biological sensors, de-
pends on the continued interest of all medical specialties, especially veteri-
nary medicine.

Although the recent development and use of biomedical lasers may be a

signiﬁcant step ahead of mechanical instrumentation, it falls short of what is
needed to be considered as the optimal ‘‘light knife’’ for every surgical situa-
tion. Considering diﬀerences in laser–tissue interaction, it is still very uncertain
whether an ‘‘ideal’’ laser wavelength will ever exist. The promised ben-
eﬁts, however, of lasers in general surgery are a combination of reduced mor-
bidity, better overall clinical results, an eventual reduction in expense for
patients/clients, more productive use of operating room facilities, and in-
creased eﬃciency of the surgical staﬀ. These advantages coupled with objec-
tive evaluations of current surgical instrumentation should place biomedical
lasers at the forefront of twenty-ﬁrst century medical technology. Discount-
ing future use of free-electron lasers with multiwavelength variability, accep-
tance of biomedical use of lasers with a ﬁxed-wavelength has depended more
on cost, capability of ﬁberoptic delivery, portability, ﬂexibility, ease of use,
and dependability.

Present-day medicine uses many diﬀerent types of biomedical lasers. Each

instrument is usually acquired for a speciﬁc purpose, such as dermatologic
or endoscopic applications. Overall, laser energy can be an extremely precise
method for tissue removal or cellular destruction. Medical lasers are expen-
sive and require a dedication to proper use and objective evaluation. Lasers
in common use today are the CO

, neodymium:yttrium aluminum garnet

(Nd:YAG), argon (Ar), potassium titanyl phosphate (KTP) or frequency-
doubled YAG, ruby, diode, holmium (Ho:YAG), erbium (Er:YAG), and
dye lasers [3]. The following general description can be used as a guide to
medical lasers. In no way should it be considered a complete discussion. Laser
types, wavelength preference, energy parameters, and delivery devices are
changed frequently, because they are closely aligned with changes in today’s
technologic advancements in computer hardware and software.

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

Medical lasers

Carbon dioxide laser (10,600 nm)

The CO

laser was one of the ﬁrst medical lasers used for tissue abla-

tion. It was developed in 1964 by C.K.N. Patel at Bell Laboratories [4].
At 10,600 nm (10.6 lm), the wavelength is ideal for cutting and vaporiza-
tion because it is highly absorbed by water. It can cut tissue cleanly when
the beam is focused onto the target and can debulk tissue by photovapor-
ization when the beam is defocused. It is considered a far-infrared (IR)
wavelength even though it emits at the short wavelength end of the far-IR
spectrum, and the beam is invisible to the eye. The CO

laser produces

light that does not transmit through quartz or glass ﬁbers. Currently, two
basic types of surgical CO

lasers are available: sealed tube and free-

ﬂowing devices. Sealed-tube lasers have a ‘‘shelf life’’ (i.e., the expected life
of the laser tube before it needs recharging with the gain medium). The anti-
cipated shelf life of a sealed metal tube laser can be longer than 10 years,
depending on the technology used by the manufacturer and the amount
of clinical use. Sealed-tube technology uses either direct electrical current
(DC) or radiofrequency (RF) to excite the gain medium in a CO

laser.

RF excitation sealed-tube CO

lasers have been growing in popularity

because they can generate more power and can work well at lower powers.
Sealed-tube CO

lasers are mechanically and electronically simpler, tend to

be smaller, produce less noise than free-ﬂowing lasers, and are capable of
emitting up to 20 to 30 W. A free-ﬂowing CO

laser requires a replaceable

external gas cylinder containing a special mixture of gases as the gain me-
dium (Fig. 1). CO

is the light emitter, nitrogen helps excite CO

, and

helium is used as a buﬀer gas for heat transfer [5]. Free-ﬂowing lasers have
been commonly sold on the secondary market (used lasers from human
hospitals) to veterinarians and usually require consideration of purchasing
a maintenance contract in addition to the cost of the device. They are
usually large, more complex devices that require periodic manufacturer’s
maintenance for proper alignment and power output, but have capabilities
of producing more than 100 W of CO

laser power.

lasers range in size and power from very large units (>100 W) to

small devices delivering 20 W or less that are more compatible for small
animal surgery. Knowledge of laser tissue–interaction and laser physics
may deter the informed laser surgeon from purchasing high-power CO

lasers (>20 W) for most procedures in small animal surgery. The ability
to exceed 20 W when performing larger ablative procedures may be an
advantage. Historically, CO

lasers have been used as a continuous wave

(CW) laser. Control of energy delivery and pulse characteristics (super-
pulse) or using temporal/spatial scanners is more important, however, for
ablative procedures requiring extreme precision more than is laser power
alone.

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

Diode lasers

Developed in 1972, semiconductor diode lasers have progressed tremen-

dously in concert with other aspects of medicine. Engineering and commer-
cial speciﬁcations have allowed advancement of devices with wavelengths
varying from approximately 635 to 980 nm. The diode lasers with the most
medical signiﬁcance are gallium aluminum arsenide (GaAlAs) or indium
aluminum arsenide devices (InGaAs) at 780 to 980 nm. Laser light output
is generated when electric current is passed through the diode. Individual
diodes emit light from the edge of a wafer or from their surface. Standard
‘‘single-emitter’’ diodes can be combined on the same semiconductor chip

Fig. 1. Articulated arm delivery system in a free-ﬂowing, DC stimulated carbon dioxide laser
(Sharplan Model 743, Sharplan Lasers, Inc., Allendale, NJ). Note: This laser is no longer
manufactured. Sharplan Lasers, Inc. is now part of Lumenis, Inc., Santa Clara, CA.

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

to achieve very high output power from a device that is still very small.
High-power diode lasers generate laser emission with an electrical-to-optical
conversion eﬃciency of 30% to 50%, making them the most eﬃcient lasers
available. These direct diode laser systems collect diode emission and chan-
nel it onto tissue using an appropriate delivery system [6]. Coupling diode
laser energy directly to ﬁberoptic delivery advices is a tremendous advantage
when considering endoscopic application and minimally invasive surgical
techniques. Therapeutic devices that use semiconductor diode lasers were
ﬁrst approved for surgical use in this country in 1989. Diode lasers (1–4 W)
are also used for photocoagulation of retinal and other ocular tissues and
have been used for ophthalmologic applications since approximately 1984.
The compact size and high eﬃciency oﬀer signiﬁcant ergonomic and eco-
nomic advantages. High-power, semiconductor diode lasers appropriate for
other surgical applications have been recently introduced for a variety of
uses (Fig. 2). These lasers currently provide up to 15 to 60 W at 810 nm
or 980 nm; wavelengths that can penetrate deeply into most types of soft
tissue and can produce tissue interactions comparable to the Nd:YAG laser
(1064 nm) [7,8]. Considering whether a diode laser emitting 810-nm wave-
length is superior or inferior to a diode laser emitting 980 nm is an exercise
in physics and laser-tissue interaction. Furthermore, the theoretical diﬀer-
ences (980 nm is somewhat higher in its water absorption coeﬃcient charac-
teristic than 810 nm) on a tissue target should be negligible to most laser
surgeons. More importantly, the delivery system, a ﬁber in contact or non-
contact mode, and the laser energy parameters will provide a greater impact
on perceived tissue interaction.

Although diode lasers are especially useful for some surgical applications,

the direct diode systems used today have some limitations. The beam quality

Fig. 2. Diode laser (Diomed, Inc., Andover, MA).

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

of high-power diode lasers limits the amount of power that can be coupled
eﬃciently through small core ﬁbers. Most high-power (25–60 W) direct-
diode systems use 400 to 600 lm diameter ﬁbers. Fiber core sizes in the 200
to 300 lm range may be needed in the near future for some applications
using miniaturized endoscopes. Narrow wavelength coverage is another
shortcoming of direct-diode laser systems. Currently, diode laser materials
are practical for generating high-output powers at wavelengths in the 635
to 2000 nm range. High-power devices that can generate yellow, green, blue,
and even near-ultraviolet (UV) and mid-IR wavelengths may be possible in
the future. Diode lasers are continuous-wave devices with little energy-storage
capacity. They cannot produce the high peak power needed for some medical
applications, such as lithotripsy, where production of a photoacoustic eﬀect is
required or in some dermatologic applications where high peak powers are
required for therapeutic results. To overcome this limitation and still preserve
the advantages of using diode lasers (i.e., size, reliability, ruggedness), diode-
pumped solid-state lasers will become more important [6].

Diode lasers can be used with ﬁber delivery accessories in noncontact

mode for tissue coagulation (power requirements of 5–25 W CW), and for
non-contact tissue vaporization (power requirements of 25–60 or greater
W CW). For precise incisional applications, ‘‘hot-tip’’ quartz, sapphire, or
so-called ‘‘dual use’’ ﬁbers can be used (power requirements of 5–20 W
CW) in contact mode. As mentioned, diode lasers can be used for many
of the same applications as 1064 nm CW Nd:YAG lasers [9]. Surgical diode
lasers oﬀer considerable advantages, however, compared with the Nd:YAG
laser. They are smaller, lighter, require less maintenance, are extremely user-
friendly, and can be more economical. Some predict that prices for diode
lasers will eventually drop to the point where they may be competitive with
high-end electrosurgery devices [10].

Other applications for diode laser energy include chromophore-enhanced

tissue ablation and coagulation, tissue fusion or laser welding, and PDT
therapy [1,11,12]. Diode laser wavelengths of 805 to 810 nm have been used
for tissue welding because applications have been centered around the peak
absorption spectrum of indocyanine green (780–820 nm), which is the selec-
tive chromophore used in a ﬁbrinogen-based solder [11]. Finally, the small,
convenient size coupled with reliability and user friendliness has also focused
extensive diode laser development for applications in PDT therapy [8].

Nd:YAG laser (1064 nm)

The Nd:YAG or ‘‘YAG laser’’ is a solid-state laser that diﬀers from the

laser because the wavelength allows transmittance though tissue, in

addition to surface absorption. Powers of up to 100 W can be delivered
through small-core optical ﬁbers that can easily be inserted through the
accessory channels of standard gastrointestinal (GI) endoscopes. The
Nd:YAG laser was one of the ﬁrst lasers to be used in veterinary medicine

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

because of its ﬁber delivery and endoscopic accessibility. Transendoscopic
use of the Nd:YAG laser in the horse has been and continues to be an eﬀec-
tive method for treating upper airway obstruction and for some endoscopic
urogenital procedures [1,13]. It has also been used for soft tissue procedures
in small animals, including prostatic resection, perianal ﬁstula ablation,
vaporization of facial tumors, and even ablation of a brain tumor [13–17].
Advantages of approaching conditions with limited anatomic access, perfor-
mance of upper respiratory and urogenital procedures with local rather than
general anesthesia, and a decrease in morbidity time have provided the moti-
vation for continuing this extremely successful eﬀort. Because the Nd:YAG
laser has less speciﬁc absorption by water and hemoglobin than the CO

and

Ar lasers, the depth of thermal injury can exceed 3 mm in most tissues,
which can be useful for coagulation of large volumes of tissue [18]. Rapid
tissue vaporization in noncontact (free-beam) mode is possible with a bare
ﬁber; however, collateral thermal injury may be substantial. Soft tissue ap-
plications using noncontact or free-beam mode usually require power levels
approaching 100 W. The use of various temporal emission modes, includ-
ing CW and pulsed modes (free-running, Q-switched, and mode-locked),
allows extreme versatility in power delivery when using the Nd:YAG laser
for many clinical applications in soft tissue surgery, ophthalmology, and
urology.

Frequency-doubled Nd:YAG or KTP laser (532 nm)

The frequency-doubled Nd:YAG laser, also known as KTP (potassium

titanyl phosphate) lasers, emits a visible green light and is basically equiva-
lent to the Ar lasers used in many surgical and dermatologic applications.
Present-day clinical applications use photothermal reactions to coagulate,
vaporize, or cut soft tissue. Absorption of the 532-nm wavelength is negligi-
ble in water. The visible green laser beam passes through water and saline
with virtually no absorption, which is extremely important in a wet or
ﬂooded surgical ﬁeld. Because the 532-nm wavelength is strongly absorbed
by the oxyhemoglobin component of blood, it can be used eﬃciently and
precisely to heat blood-perfused soft tissue. In whole blood, absorption
depth at 532 nm is approximately 0.5 mm. This strong absorption can actu-
ally be a problem if the target tissue is covered with blood, because the laser
energy will be severely attenuated before it reaches the tissue’s surface [19].

One currently manufactured frequency-doubled Nd:YAG laser (Model

800 Series Laserscope, Laser Scope, Inc., San Jose, CA) can provide either
532 nm or 1064 nm through the same optical ﬁber. The 532-nm wavelength
is used for precise cutting and vaporization. By switching to the 1064-nm
wavelength, the same laser and ﬁber delivery system can be used for deep
tissue coagulation or rapid vaporization when only modest surgical preci-
sion is required. The laser is also used by the manufacturer as a dye laser-
pumping source to control PDT interactions.

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

Ar laser (458 and 524 nm)

The blue-green Ar laser is strongly absorbed by hemoglobin and is espe-

cially useful in nonbleeding vascular lesions when precision and minimal
penetration (approximately 1 mm) is required. Although heavily absorbed
by blood, Ar laser energy can be readily transmitted through water, gastric
ﬂuid, aqueous or vitreous humor, and urine. Consequently, this laser can be
used to precisely cut, vaporize, and superﬁcially coagulate soft tissue that is
well perfused with blood. Treatment of hemoglobin-poor tissue generally
relies on the production of carbonized tissue or ‘‘char’’ for eﬃcient heating
of tissue. Bare ﬁbers can be used in contact or noncontact modes for cutting,
vaporization, or coagulation. Although older versions often lacked enough
power to vaporize target tissue, newer 15-W Ar lasers are more eﬃcient for
vaporization and cutting applications.

Ruby laser (694 nm)

Although ﬁrst investigated for its medical potential by Maiman in 1961, the

ruby laser has not received widespread use. It was resurrected in the late 1980s
as a medical device for removing tattoos and birthmarks. The 694-nm wave-
length is absorbed strongly by dark pigments, such as melanin, and the pig-
ments used for making tattoos, but only weakly by hemoglobin. Therefore,
the visible ruby laser wavelength can penetrate several millimeters into skin
without being severely attenuated by blood. Because of this fact, the ruby laser
is used in selective photothermolysis procedures for removing tattoos [19].

Holmium lasers (2100 nm) and erbium lasers (2900 nm)

Clinical solid-state Ho:YAG lasers have appeared recently for arthro-

scopic surgery, general surgery, laser angioplasty, and thermal sclerostomy.
Other applications include laser discectomy, removal of sessile polyps in the
GI tract, and otorhinolaryngeal procedures. The main beneﬁt of the Ho:
YAG laser is its ability to cut and vaporize soft tissue somewhat like a CO

laser, with the added advantage that holmium energy can be delivered through
ﬂexible, low OH, quartz, or polyamide optical ﬁbers. Good surgical precision
and control can be obtained with a bare optical ﬁber. Unlike visible wave-
length lasers, and again like the CO

laser, photothermal interactions with the

Ho:YAG laser do not rely on hemoglobin or other pigments for eﬃcient
heating of tissue. The water component of tissue is responsible for absorbing
Ho:YAG laser energy (2100 nm) and for converting it to heat. The depth of
absorption is quite shallow at approximately 0.3 mm. When cutting or va-
porizing tissue, actual zones of thermal injury vary from 0.1 to 1 mm, depend-
ing on exposure parameters and the type of tissue. These small thermal
necrosis zones provide better surgical precision and adequate hemostasis.

Current holmium instruments are ﬂashlamp-pumped systems. The active

laser medium consists of a chromium-sensitized YAG host crystal doped

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

with holmium and thulium ions. This active medium is referred to as Tm,
Ho, Cr:YAG, or THC:YAG and is common to all Ho:YAG laser medical
devices. Unlike the CO

laser, higher power Ho:YAG lasers cannot operate

in a CW mode at room temperature. The relatively low pulse rates (5–20 Hz
with 250–350 lsec pulses) available from most Ho:YAG lasers may be con-
sidered a disadvantage because cutting may be slow or may result in jagged
tissue edges during incisional applications. In addition, at higher pulse ener-
gies (

‡1 J), considerable amounts of acoustic or photomechanical energy are

generated in tissue. An audible acoustical ‘‘pop’’ may be generated and actu-
ally heard during laser application. Acoustic energy may be considered an
advantage, however, when using holmium energy for photodisruptive
(photothermal/photomechanical phenomena) procedures, such as lithotripsy
of gallstones or urologic calculi [20].

Another mid-IR, solid-state laser is the Er:YAG laser. Its wavelength

(2900 nm) is more strongly absorbed in water. Dental applications, includ-
ing hard tissue ablation (Food and Drug Administration [FDA]-approved)
and incisional applications, are considered appropriate for this wavelength.
Hemostatic ability is minimal, however, and lack of readily available deliv-
ery ﬁbers has hindered its potential use. Although somewhat brittle, sap-
phire ﬁbers have been used for Er:YAG energy delivery [19].

Dye laser (variable wavelength with dyes—400 to 1000 nm)

Developed at the IBM Laboratories in 1966, dye lasers oﬀer an advantage

of ‘‘tunability’’ of wavelength over a considerable range to obtain absorption
coeﬃcients and tissue interaction characteristics applicable to multiple med-
ical specialties, including oncology, ophthalmology, urology, and especially
dermatology [5]. Pulsed and CW dye lasers use an active laser medium, con-
sisting of an organic dye dissolved in an appropriate solvent. For the dye
laser to work, the dye solution must be recirculated at high velocity through
the laser resonator. Dye lasers are useful for medical applications because
they can generate high-output powers and pulse energy at wavelengths
throughout the visible wavelength spectrum (400–700 nm). They are usually
pumped by Ar lasers, ﬂashlamps, or a frequency-doubled Nd:YAG laser.
Dye lasers have been used for lithotripsy of biliary and urologic calculi
(pulsed), activating photosensitizers for PDT therapy (CW), ophthalmologic
operations (pulsed or CW), and dermatologic applications (pulsed and CW)
including treatment of birthmarks and removal of tattoos [19].

Laser delivery systems

A delivery system is deﬁned as the optical hardware needed to transfer

energy from the laser to the treatment site. Devices for guiding laser beams
to the patient include articulated arms with internal mirrors, hollow wave-
guides, and optical ﬁbers. Articulated arms and hollow waveguides are used

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

with laser wavelengths (2.8–10.6 lm) that cannot be transmitted through
conventional glass or quartz ﬁber optics. The CO

laser produces far-IR

light and is included in this category. Currently, CO

laser light must be

delivered to the tissue through a hollow tube called an articulated arm or
through a hollow waveguide. The articulated arm is a tube with mirrors
aligned in joints that reﬂect light into a system of lenses that create a colli-
mated and focused beam. The articulated arm can be somewhat fragile and
diﬃcult to manipulate in a small operating room; however, some manufac-
turers have worked diligently to minimize this limitation. Because the laser
beam is invisible to the eye, a low-power red helium-neon (633 nm) or diode
(635–660 nm) laser is usually used to provide an aiming beam. CO

lasers

using articulated arms for energy delivery must be realigned periodically
during scheduled maintenance checks (Fig. 1).

As mentioned, laser energy delivery through an articulated arm has

inherent disadvantages because of size of the arm, portability, and its inabil-
ity to be used for minimally invasive procedures through endoscopic visual-
ization. The addition of attached semirigid hollow waveguides to some CO

systems enhances their ﬂexibility for performing many laser procedures.
Waveguides can direct CO

energy delivery economically and eﬃciently.

Hollow waveguides are manufactured from high-quality stainless steel, ﬂex-
ible glass tubes, and other materials that have reﬂective interiors to direct
energy. Although laser energy decays as it traverses the length of the hollow
waveguide, software included in some CO

devices will compensate for this

energy loss to provide for consistent energy delivery at the termination.

Hollow waveguides capable of transmitting CO

energy from a compact,

robust laser device have been one of the major inﬂuences to drive laser tech-
nology into veterinary medicine. Although this particular laser (AccuVet
CO

Laser, Lumenis, Inc., Santa Clara, CA) delivers a noncollimated beam

at the tissue target site, various tapered tips (0.3–1.4 mm in diameter) con-
centrate and direct the energy, which increases or decreases the power den-
sity, depending on the tip diameter (AccuVet CO

Laser, Lumenis, Inc.,

Santa Clara, CA) (Fig. 3). Although there are still drawbacks because cur-
rently available hollow waveguides are not readily endoscopically deliverable,
improved waveguide development and advancing CO

laser ﬁber technologies

should overcome this limitation in the forseeable future.

The availability of functional and inexpensive optical ﬁbers for laser

delivery has played a crucial part in the acceptance of lasers for medical
applications. The ﬁbers used in laser medical delivery are most often com-
posed of quartz glass and have diameters ranging from 0.1 to 1 mm. Laser
energy is contained within and follows the bends and curves (total internal
reﬂection) of the ﬁber within certain limits (eg, numeric aperture), until it
reaches the tip where it exits [21]. Although conﬁgurations of ﬁber tips
(eg, ﬂat, orb, chisel, conical) and their ability to transmit energy are a science
in their own right, delivery parameters are primarily based on two factors:
contact (hot-tipped) delivery or noncontact delivery (Fig. 4). In general,

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

lower power (5–20 W) is delivered through contact tips. Contact tip ﬁbers
include sculpted quartz ﬁbers, contact-tipped sapphire ﬁbers, metal-capped
ﬁbers, temperature-controlled bare ﬁbers, and dual eﬀect (used both in con-
tact and noncontact modes) ﬁbers. Although the use of contact tips for
endoscopic application is widely accepted, some tips are too large to insert
through ﬂexible endoscopes. Most sculpted or cleaved quartz ﬁber tips used
in contact mode must be ‘‘carbonized’’ (i.e., contact application of ﬁber to
target tissue or a sterile wooden tongue depressor to form a layer of carbon-
ized particles so the ‘‘hot tip’’ becomes eﬀective in tissue). Finally, the ability
to guide laser energy, ﬁber thinness, ﬂexibility, economy, and ruggedness
makes quartz optical ﬁbers essential for endoscopic applications.

Laser scanners or pattern generators are available as accessories to CO

and some solid-state lasers, such as the Er:YAG or KTP lasers. They were
introduced to convert a CW or pulsed beam of laser energy into a scanned,

Fig. 3. Hollow waveguide delivered CO

laser (AccuVet

Carbon Dioxide Laser, Lumenis,

Inc., Santa Clara, CA).

Fig. 4. Conﬁgurations of laser optical delivery ﬁbers used with diode and Nd:YAG lasers.

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

shuttered beam to reduce tissue carbonization and to enhance precise vapor-
ization of tissue. Laser scanners can increase the speed of treatment and can
provide better control of beam overlap. They provide a nonaligned treatment
pattern and decrease laser beam ‘‘dwell time’’ on speciﬁc target areas, which
allows the thermal energy in adjacent tissue to cool adequately between
pulses [19]. Computerized or robotized scanning devices are used in some
models of the larger lasers applied in aesthetic laser surgery. Smaller, less
expensive ﬂashscanners may scan a 100-lm focused beam in a spiral pattern
on the target tissue with the aid of rapidly oscillating mirrors or a mechanical
device that rotates the waveguide termination tip in the laser handpiece
(Fig. 5).

Biomedical lasers in veterinary medicine

Early reports concerning the use of lasers for medical applications

involved animals—either as experimental models or as clinical veterinary
patients. In 1968, the removal of a vocal cord nodule in a dog demonstrated
one of the ﬁrst practical clinical applications of the CO

laser as a precision

surgical instrument [22,23].

Many other biomedical laser research teams have also relied on animal

models for determining initial laser parameters and eﬃcacy. At this stage
of research, veterinarians can and should be the main catalyst for the ad-
vancement of biomedical laser technology and laser-based therapeutic tech-
niques with potential human application. Often, objective protocols will prove
some ideas and applications as impractical for veterinary clinical purposes.
Although the idea or development of a new device may be inapplicable

Fig. 5. CO

laser scanner used for char-free tissue ablation (NovaScan

, Lumenis, Inc., Santa

Clara, CA).

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

to ‘‘mainstream veterinary medicine’’ because of the current economic
limitations, our participation as an equal partner on the biomedical research
team places us in a strategic position to be leaders in today’s total health care
establishment.

Since their introduction into veterinary medicine in the 1970s, high-

powered surgical lasers have been used primarily for photothermal procedures
to vaporize or ablate the target tissue. Techniques have often been described
using a variety of device settings that may or may not take into account objec-
tive evaluation of the technology and give appropriate attention to laser
tissue–interaction phenomenon. It is imperative that clinicians learn the fun-
damentals and the applied aspects of the technology for clinical practice.

New procedures involving other aspects of laser energy interaction in-

clude laser lithotripsy and low-level laser photobiostimulation. Laser ablation
of intervertebral discs has also become a procedure using minimally invasive
techniques through ﬁberoptic energy.

Low-level laser therapy (photobiostimulation)

Biostimulation using light energy, which is usually considered a photo-

chemical eﬀect, has attracted interest in both the clinical and research arenas
in both veterinary and human medicine. To many scientists and clinicians,
the idea that low-intensity light energy (<500 mW average power) can pro-
mote and upgrade metabolic processes that result in tissue repair and pain
relief is unbelievable and akin to ‘‘snake oil’’ practice [24]. At a minimum,
it is on the fringes of accepted practice in the unconventional aspects of com-
plementary and alternative veterinary medicine. Yet, reports from almost
every region of the world indicate that low-intensity lasers promote the
repair process of skin, tendons, ligaments, bone, and cartilage in experimen-
tal animals and wounds of various etiologies in humans. Reports that sug-
gest the contrary complicate the matter, creating the present situation in
which laser or low-energy photon therapy is viewed with extreme skepti-
cism. Several manufacturers throughout the world have developed devices
for using low-level laser energy in human medicine. Marketing eﬀorts in the
United States have been directed to veterinarians since the FDA has not yet
approved this type of laser therapy for human use (Fig. 6) [25].

Biostimulation, or low-energy photon therapy, is deﬁned as nonthermal

interaction of monochromatic radiation with a target site [6]. Although the
physiologic interaction for this type of energy application on tissue is still
not understood, low-energy lasers have been reported to modulate various
biologic processes, such as mitochondrial respiration or adenosine triphos-
phate synthesis, to accelerate wound and joint healing, and to promote mus-
cle regeneration [26,27]. In addition, pain attenuation or pain removal has
been reported using this type of low-energy photon therapy. Recommended
veterinary applications include ﬁrst aid treatment for traumatic and surgical
wounds, strains; musculoskeletal pain and dysfunction; rheumatoid arthritis

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

and osteoarthritis; neurologic applications, such as neuralgia, and other
nerve injuries; and sport injuries ranging from contusions to muscle tears [28].

Devices used for biostimulation vary in their optical properties. Often,

laser wavelengths are in the visible or near-IR range. Laser power output
is not suﬃcient to cut or vaporize tissue. Advocates have also reported simi-
lar results using less expensive light sources (wider wavelength bands, non-
coherent light sources). More research is being conducted in this area as
low-level laser or photon therapy becomes less controversial, and peer-
reviewed case reports or projects are being reported in the veterinary litera-
ture [29–31]. Methods are also being formulated to provide objective and
replicable results to prove the eﬃcacy of this therapy. It is incumbent on the
manufacturers of these devices to support these types of investigations
rather than promote the technology based solely on anecdotal reports.

Laser lithotripsy

Gastrointestinal and urologic applications have primarily involved uses

in soft tissue surgery. Recently, however, the application of laser photother-
mal and photomechanical energy through endoscopically delivered optical
ﬁbers to break down urologic and biliary calculi has been approved and
practiced in humans. Much of the preliminary work, including mechanism
of action and early clinical reports, originated from veterinary medical
applications. Currently, the ﬂash-lamp pulsed dye laser and the Ho:YAG
lasers are used for laser lithotripsy in veterinary medicine.

Fig. 6. Low-level laser energy biostimulation and therapy device (Veterinary Therapy Laser,
Model PLLSD0009, American Veterinary Laser, Farmington Hills, MI).

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

The pulsed dye laser operates at a wavelength of 504 nm with 1.0 lsec

pulses. Urolith fragmentation is accomplished by a photoacoustic and mech-
anical eﬀect through formation of an energy plasma that consists of a rapidly
expanding cloud of generated electrons and ions. The plasma absorbs addi-
tional laser energy and generates a symmetrically expanding cavitation bub-
ble. Urolith fragmentation is caused by a rapid collapse of the cavitation
bubble, creating a strong acoustic shockwave that exceeds the tensile
strength of the urolith (Fig. 7).

Because energy dissipates rapidly with increased distance, the pulse dye

laser is associated with low risk of soft tissue damage. Energy absorption of
this laser is related, however, to composition of the urolith, which decreases
its eﬀectiveness on light-colored calculi. Flash-lamp pulsed dye lasers are
high maintenance devices and have virtually been replaced by the Ho:YAG
laser as a laser lithotripter.

The mechanism of Ho:YAG lithotripsy is mainly photothermal. Unlike

the dye laser, the pulsed energy of the Ho:YAG laser is strongly absorbed
by water. Direct contact of the ﬁber perpendicular to the calculus is required
for eﬀective use in liquid media because a cavitation bubble is formed by
vaporization of water molecules. The bubble is pear shaped and undergoes
asymmetric expansion and collapse. This results in an acoustic emission and
shockwave generation. Coupled with an irregularly shaped cavitation bub-
ble, a vapor channel is formed that eﬀectively conducts laser energy to the
stone (‘‘Moses Eﬀect’’). Consequently, the surface of the calculus is ablated
by direct laser radiation and a rapid increase in surface temperature.
Because of a longer pulse duration (250–350 ms), vaporization of water
molecules is continuous, and expansion of interstitial water and vapor results
in surface ejection of fragments from the calculus (Fig. 8). Calculi compo-
sition does have an eﬀect on Ho:YAG lithotripsy eﬃciency [20,32]. In
addition, eﬃcacy of lithotripsy for urologic calculi seems to vary among ani-
mal species, which also may result from diﬀerences in stone composition.

Fig. 7. Flashlamp pulsed dye laser lithotripsy of a urologic calculus (in vitro).

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

Considering current technologies, lithotripsy using the ﬂash-lamp pulsed dye
laser seems to be more successful in the horse than when using the Ho:YAG
laser. The Ho:YAG laser has been successfully used, however, in most other
animal species (i.e., dog, pig, cow, llama), and considering its solid-state
characteristics, reliability, portability, and cost, it will most likely remain the
primary device for laser lithotripsy in veterinary medicine.

Laser intervertebral disc ablation

A percutaneous approach for photothermal ablation or vaporization of

the nucleus pulposus in lumbar discs using laser energy has been reported
as a treatment of intervertebral disc disease in humans and dogs [33].
Although the Nd:YAG, KTP, and diode lasers have also been used for this
minimally invasive procedure, the Ho:YAG laser has advantages over other
approved lasers with diﬀerent wavelengths. As mentioned previously,

Fig. 8. Ho:YAG laser lithotripsy of a biliary calculus (in vitro).

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

because the Ho:YAG wavelength is strongly absorbed by water, depth of
tissue penetration is limited, and zones of necrosis and collateral thermal
eﬀects are minimized because of the high water content of the nucleus pul-
posus. Using the dog as a model, investigators have shown that acute and
chronic histopathologic eﬀects of percutaneous Ho:YAG laser disc ablation
on neighboring tissue are minimal. Proponents of laser discectomy claim
positive results in humans are related to a decrease in intradiscal pressure
caused by a decrease in volume of the nucleus pulposus after ablation.
Further disc extrusion also can be prevented; however, disc ablation is not
eﬀective when sequestration of a herniated fragment has occurred.

Surgical fenestration of thoracolumbar intervertebral discs in dogs has

been recommended primarily as a prophylactic procedure to prevent further
herniation of nucleus pulposus from a partially herniated disc and exacerba-
tion of associated clinical signs. The procedure should also reduce the
chances of subsequent herniation of other discs in seven to eight statistically
signiﬁcant locations. Considered a major surgical procedure by most veter-
inary surgeons, disc fenestration has the potential for postoperative compli-
cations, including pneumothorax, spinal cord and nerve injury, and
hemorrhage. Percutaneous Ho:YAG laser ablation of canine thoracolumbar
intervertebral discs has the advantage of being a minimally invasive proce-
dure, which can decrease postoperative complications, shorten recovery
time, and reduce medical expenses (Fig. 9A, B).

On the basis of eﬃcacy and safety of a preliminary clinical study [34], an

additional 250 cases involving dogs diagnosed with thoracolumbar interver-
tebral disc disease have undergone prophylactic percutaneous laser disc
ablation from the tenth thoracic to the fourth lumbar vertebra (T10-11 to
L3-4) [K.E. Bartels, et al; work in Progress]. A recurrence rate of less than
5% coupled with minimal postablation complications over an eight-year pe-
riod has provided the incentive to continue using laser disc ablation as a
viable alternative technique to surgical fenestration. In addition, laser disc
ablation of the cervical and lumbosacral areas may also prove to be a viable
technique for the future.

Future innovations

The use of lasers in medicine is an exciting treatment modality that will

continue to produce innovative and new methods for managing diseased tis-
sue. Research focused on basic laser–tissue interaction and selective tissue
destruction will become increasingly important. Orthopedic use of biomedi-
cal lasers in veterinary medicine has been somewhat limited. The CO

laser

has been used for ablation of methylmethacrylate and has the potential to be
beneﬁcial during revision of total hip prostheses [35]. As delivery methods
improve and as devices with appropriate wavelengths (Ho:YAG—2.1 lm;
Er:YAG—2.8 lm) become more economically available for veterinary use,

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

orthopedic applications will undoubtedly increase as they have in human
medicine for cartilage reshaping and ablation through arthroscopic visuali-
zation. The CO

laser also has potential for use in open surgical procedures

where precise ablation is necessary, such as during joint exploration [36,37].

The use of lasers as diagnostic tools and sensors is one of the fastest

growing branches of biomedical laser development. Clinical applications
involving noninvasive recognition of malignant cells, abnormal tissue, or ab-
normal metabolites have tremendous potential. Use of available and future
laser diagnostic technology could have a signiﬁcant impact on the veterinary
profession. Blood, urine, or tissue can be illuminated by a laser beam, and
by analyzing the reﬂected or luminescent light collected and transmitted
by a second ﬁber, information is obtained about that biologic ﬂuid or
tissue [33].

Because technical knowledge and instrumentation for laser surgery are

expanding almost exponentially, the availability of equipment is also

Fig. 9. Ho:YAG laser ablation of thoracolumbar intervertebral discs. (A) Seven myelographic
(20 gauge–21/2 in) needles are percutaneously inserted under ﬂuoroscopic guidance into
intervertebral disc spaces T10-11 to L3-4. (B) Ho:YAG laser ﬁber is inserted through each
needle to the level of the nucleus pulposus, and the disc material is vaporized or undergoes
coagulative change.

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

expanding as rapidly. With increased use, it is essential that our current clin-
ical and research activities accurately reﬂect responsible medical and scien-
tiﬁc use. Strategies or ‘‘gimmicks’’ in the form of new and unique equipment
and miracle cures can attract individuals interested in oﬀering special treat-
ments that have no proven beneﬁt. An objective and practical approach to
laser surgical procedures in veterinary medicine is essential if the total ben-
eﬁcial potential is to be realized. ‘‘Zap and vaporize’’ techniques coupled
with a ‘‘burn and learn’’ philosophy can do potential harm to patient and
operator and can outweigh any beneﬁcial eﬀect. These concepts have no
place in the objective use of lasers in veterinary medicine. A concerned eﬀort
must be made to evaluate the use of a laser for its potential patient beneﬁt,
rather than portraying it as a miracle device of the twenty-ﬁrst century that
is advertised on an illuminated billboard in front of a hospital. Although the
use of biomedical lasers has created an entirely new deﬁnition for perform-
ing surgery, a surgeon’s knowledge of pathophysiology and technical exper-
tise must be the primary factor to determine whether a laser should be used
for a particular surgical procedure in lieu of more conventional approaches.
Finally, the use of any new technology, including the application of bio-
medical lasers in veterinary medicine, does not replace the basic issues and
essential rules of a surgical practice, such strict aseptic technique, appropri-
ate use of instruments, and good surgical judgment.

Summary

Future use of lasers in medicine depends on the active participation of

veterinarians in the inception and development of new devices that meet the
needs of the entire medical profession. The sensible clinical approach that
must be taken every day in the practice of veterinary medicine equips the
veterinarian with a unique ability to understand the practical applications
of biomedical lasers. Veterinary medicine can and should be in the forefront
during these exciting times, adding an essential dimension to development of
this twenty-ﬁrst century technology.

References

[1] Tullners EP. Transendoscopic contact neodymium:yttrium aluminum garnet laser cor-

rection of epiglottic entrapment in standing horses. J Am Vet Med Assoc 1990;144:1971–80.

[2] Itzkan I, Drake EH. History of lasers in medicine. In: Arndt KA, Dover JS, Olbricht SM,

editors. Lasers in cutaneous and aesthetic surgery. Philadelphia: Lippincott-Raven; 1997.
p. 3–10.

[3] Katzir A. Medical lasers. In: Lasers and optical ﬁbers in medicine. San Diego, CA: Ac-

ademic Press; 1993. p. 180–209.

[4] Patel CKN, McFarlane RA, Faust WL. Selective excitation through vibrational energy

transfer and optical maser action in N

-CO

. Phys Rev 1964;13:617–9.

513

K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

[5] Hecht J. Carbon dioxide lasers. In: The laser guidebook. New York: McGraw-Hill; 1992.

p. 159–83.

[6] Manni JG. High-power diode-based lasers for medical applications. Biophotonics Int 1997;

1:40–6.

[7] Judy MM, Matthews JL, Aronoﬀ BL, et al. DF: soft tissue studies with 805 nm diode laser

radiation: thermal eﬀects with contact tips and comparison with eﬀects of 1064 nm
Nd:YAG laser radiation. Lasers Surg Med 1993;13:528–36.

[8] Wieman TJ, Fingar VH. Photodynamic therapy. Surg Clin N Am 1992;72:609–22.
[9] Taylor DL, Schafer SA, Nordquist RE, et al. Comparison of a high power diode laser with

the Nd:YAG laser using in situ wound strength analysis of healing cutaneous incisions.
Lasers Surg Med 1997;21:248–54.

[10] Bartels KE, Zediker MS. Biomedical lasers at the cutting edge. Photonics Spectra 1993;27:

92–7.

[11] Bartels KE, Morton RJ, Dickey DT, et al. Use of diode laser energy (808 nm) for selective

photothermolysis of contaminated wounds. In: Prog Biomedical Optics (International
Society for Optical Engineers Proceedings Series), Lasers in surgery: advanced character-
ization, therapeutics, and systems V, (2395). 1995. p. 602–6.

[12] Treat MR, Oz MC, Bass LS. New technologies and future applications of surgical lasers.

The right tool for the right job. Surg Clin N Am 1992;72:705–47.

[13] Tate LP, Sweeney CL, Bowman KF, et al. Transendosocpic Nd:YAG laser surgery for treat-

ment of epiglottal entrapment and dorsal displacement of the soft palate in the horse. Vet
Surg 1990;19:356–63.

[14] Ellison GW, Bellah JR, Stubbs WP, et al. Treatment of perianal ﬁstulas with Nd:YAG

laser. Results in twenty cases. Vet Surg 1995;24:140–7.

[15] Feder BM, Fry TR, Kostolich M, et al. Nd:YAG laser cytoreduction of an invasive

intracranial meningioma in a dog. Prog Vet Neurol 1993;4:3–9.

[16] Hardie EM, Stone EA, Spaulding KA, et al. Subtotal canine prostatectomy with the neo-

dymium:yttrium aluminum garnet laser. Vet Surg 1990;19:348–55.

[17] Shelley BA, Bartels KE, Ely RW, et al. Use of the neodymium:yttrium aluminum garnet

laser for treatment of squamous cell carcinoma of the nasal planum in a cat. J Am Vet Med
Assoc 1992;201:756–8.

[18] Swaim CP, Mills TN. A history of lasers. In: Krasner N,

editor. Lasers in gastro-

enterology. New York: Wiley-Liss; 1991. p. 3–23.

[19] Fuller TA, Intintoli A. Laser instrumentation. In: Arndt KA, Dover JS, Olbricht SM,

editors. Lasers in cutaneous and aesthetic surgery. Philadelphia: Lippincott-Raven; 1997.
pp. 52–64.

[20] Spindel ML, Moslem A, Bhatia KS, et al. Comparison of holmium and ﬂashlamp

pumped dye lasers for use in lithotripsy of biliary calculi. Lasers Surg Med 1992;12:
482–9.

[21] Katzir A. Fiberoptic diagnosis. In: Lasers and optical ﬁbers in medicine. San Diego (CA):

Academic Press; 1993. p. 180–209.

[22] Jako GJ. Laser biomedical engineering: clinical applications in otolaryngology. In:

Goldman L, editor. The biomedical laser. Technology and clinical applications. New York:
Springer-Verlag; 1981. p. 175–98.

[23] Jako GJ. Laser surgery of the vocal cords; an experimental study with the carbon dioxide laser

on dogs. Laryngoscope 1972;82:2204.

[24] Enwemeka CS. Quantum biology of laser photostimulation [editorial]. Laser Ther 1999;

11(2):52–4.

[25] Felten RP. FDA status of biostimulation lasers. In: Abstracts of American Society for

Laser Medicine and Surgery 15th Annual Meeting. Toronto, Ontario, Canada; 1994.

[26] Collier M, Haugland LM, Bellamy J, et al. Eﬀects of holmium:YAG laser on equine

articular cartilage and subchondral bone adjacent to traumatic lesions: a histopathological
assessment. J Arthrosc Rel Med 1997;9:536–45.

514

K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

[27] Shefer G, Halevy O, Cullen O, et al. Low level laser irradiation shows no histopatholgical

eﬀect on myogenic satellite cells in tissue culture. Laser Ther 11(3):114–7.

[28] Po¨ntinen PJ. Low-energy photon therapy. In: Schoen AM, Wynn SG, editors. Comple-

mentary and alternative medicine—principles and practice. St. Louis (MO): Mosby; 1998.
p. 247–74.

[29] Ghamsari SM, Taguchi K, Abe N, et al. Evaluation of low level laser therapy on primary

healing of experimentally induced full thickness teat wounds in dairy cattle. Vet Surg 1997;
26:114–20.

[30] Hardie EM, Carlson CS, Richardson DC. Eﬀect of Nd:YAG laser energy on articular

cartilage healing in the dog. Lasers Surg Med 1989;9:595–601.

[31] Lucroy MD, Edwards BF. Low-intensity laser light-induced closure of a chronic wound in

a dog. Vet Surg 1999;28:292–5.

[32] Teichman JM, Vassar GJ, Glickman RD. Holmium:yttrium-aluminum-garnet lithotripsy

eﬃciency varies with stone composition. Urology 1998;52:392–7.

[33] Choy DSJ, Case RB, Fielding W, et al. Percutaneous laser nucleolysis of lumbar discs.

N Engl J Med 1987;317:771–2.

[34] Dickey DT, Bartels KE, Henry, et al: Use of the holmium yttrium aluminum garnet laser

for percutaneous thoracolumbar intervertebral disk ablation in the dog paper. J Am Vet
Med Assoc 1996;208:1263–7.

[35] Lange DN, Rochat MC, Bartels KE, et al. Comparison of carbon dioxide laser modalities

for removal of polymethylmethacrylate cement. Vet Comp Orthop Trauma 1997;10:25–31.

[36] Nixon AJ, Krook LP, Roth JE, et al. Pulsed carbon dioxide laser for cartilage vaporization

and subchondral bone perforation in horses. Part II: morphologic and histochemical re-
actions. Vet Surg 1991;203(3):200–8.

[37] Roth JE, Nixon AJ, Gantz VA. Pulsed carbon dioxide laser for cartilage vaporization and

subchondral bone perforation in horse. Part I: technique and clinical results. Vet Surg
1991;203(3):190–9.

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K.E. Bartels / Vet Clin Small Anim 32 (2002) 495–515

Lasers and laser–tissue interaction

George M. Peavy, DVM

Beckman Laser Institute, College of Medicine, University of California

Irvine, 1002 Health Sciences Road East, Irvine, CA 92612, USA

Light, luminescence, and lasers [1--5]

Light is electromagnetic energy. It consists of photons that emanate from a

source, travel in a waveform, and move in a linear direction until something
acts on them to alter their path of travel. The distance measured between two
consecutive crests of the waveform characterizes the wavelength of the
photon. Photons that have wavelengths from approximately 400 nm (violet)
to 750 nm (red) are discriminated as colors by the optical detectors of our eyes.
Wavelengths in the region of 100 to 400 nm are referred to as ultraviolet (UV),
and those with wavelengths longer than 750 nm are referred to as infrared (IR).

Incandescent light is produced by adding energy to a substance, such as a

light bulb ﬁlament, inducing superexcited states with the resultant release of
energy into the environment in the form of photons. Photons of multiple
wavelengths across the visible and invisible spectrum may be released by the
ﬁlament and travel in all directions away from their source. This type of
light is described as polychromatic (multiple wavelengths) and incoherent
(photons traveling in diﬀerent directions, out of phase with each other), and
is not particularly intense.

Laser light is most often produced by encasing a speciﬁc element or com-

pound in a chamber and exciting the substance by the addition of energy, gen-
erally from a ﬂashlamp or electrical current (Fig. 1A). The excited substance is
energetically unstable in its elevated energy state (referred to as a metastable
state), and prefers to return to its ground state by releasing the acquired energy
in the form of a photon (Fig. 1B). The excited states are characteristic of each
speciﬁc element or compound. Because the photons being released are coming
from a speciﬁc element or compound and are being released as that substance
moves from one speciﬁc energy level to another, the wavelength of each
photon will be the same.

Vet Clin Small Anim 32 (2002) 517–534

E-mail address: gpeavy@bli.uci.edu (G.M. Peavy).

0195-5616/02/$ - see front matter

PII: S 0 1 9 5 - 5 6 1 6 ( 0 2 ) 0 0 0 0 3 - 7

The lasing medium is encased in an elongated chamber with mirrors

mounted parallel to each other at each end of the chamber. As photons are
spontaneously released from the excited substance within the laser chamber,
those moving to the sides of the chamber are absorbed, whereas those trav-
eling toward a mirrored end of the chamber are reﬂected back through the
chamber, to be reﬂected back again by the mirror at the opposite end. As
photons travel the length of the chamber they interact with metastable mole-
cules of the lasing substance causing each excited molecule to release a
photon (stimulated emission) and return to its ground state (Fig. 1B). The
emitted photon and the initiating photon are of the same wavelength be-
cause they are emitted by the same substance at the same energy level and
will be traveling parallel and in phase with each other. The addition of more
energy to the chamber re-excites molecules to the metastable state (Fig. 1C),
where their interaction with photons previously propagated in the chamber
results in the generation of an increasingly intense beam of photons (ampli-
ﬁcation); all of the same wavelength (monochromatic) and traveling parallel
and in phase with each other (coherent). Light ampliﬁcation by the stimu-
lated emission of radiation serves as the basis for the acronym LASER and
describes in principle how the laser generates light.

The use of a shutter at one end of the lasing chamber allows release of

photons and manipulation of their path of travel to a designated location.
When a lasing substance may be excited to multiple energy levels and when
each level releases a photon of speciﬁc but diﬀerent wavelength, the laser is
ﬁtted with optical ﬁlters to allow passage of photons of only the desired

Fig. 1. The substance within a laser chamber is excited from its ground state to a metastable
energy state by exposure to an energy source (A). The metastable molecules return to their
ground state by spontaneous release of acquired energy in the form of a photon. Photons
traveling to the sides of the chamber are absorbed, whereas those traveling the length of the
chamber interact with metastable molecules, amplifying the beam within the chamber by
stimulating the emission of additional photons (B). Application of additional energy to the
chamber re-excites ground state molecules to the metastable state (C), which allows continued
beam generation while photons are reﬂected between parallel mirrors mounted at each end of
the chamber.

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G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

wavelength. In some cases, the ﬁlters on the laser may be exchanged, allow-
ing the selection of diﬀerent wavelengths from the same lasing medium.

Just as light bulbs may be named according to the luminescing substance

that they contain (eg, neon, halogen, sodium, mercury vapor), lasers are
named according to their lasing medium (eg, argon, helium-neon, krypton,
carbon dioxide [CO

], neodymium:yttrium-aluminum-garnet [Nd:YAG],

holmium:YAG, erbium:YAG). The YAG included in the name of some
lasers refers to an inert yttrium-aluminum-garnet crystal that serves to hold
a lasing element (neodymium, holmium, or erbium) in the laser chamber.
There are some fundamental diﬀerences in design and manner of beam pro-
pagation in chemical, free electron, and diode lasers; however, the beam gen-
erated is still monochromatic, coherent, and intense.

Light and tissue transformation

The inﬂuence of laser light on a tissue (or any material) is dependent on

the optical, chemical, and mechanical properties of the target tissue and the
characteristics of the incident laser beam, including wavelength, energy dis-
tribution, and time domains of exposure. A fundamental understanding of
these principles is essential for the laser surgeon, because alterations in any
one parameter can result in tremendous diﬀerences in the eﬀect on tissue.

Wavelength dependence [1,6–8]

As light interacts with a substance it may be reﬂected, transmitted, scat-

tered, or absorbed (Fig. 2), and the optical properties of a substance are char-
acterized by coeﬃcients for each of these events. All wavelengths of light do

Fig. 2. The interaction of photons with tissue is characteristic of their wavelength and the
optical properties of the tissue. Photons may be reﬂected (A), transmitted (B), scattered (C), or
absorbed (D) by tissue. The path of travel of a beam of photons in any tissue is inﬂuenced by a
combination of these events.

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G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

not react with the same substances in the same way. What we see is a complex
product of the wavelength composition of the incident light inﬂuenced by the
optical properties of the illuminated subjects.

If we look at light coming through a clear drinking glass we see the objects

on the other side of the glass because light is transmitted through the glass.
If we put milk in the glass, we see the same light coming through the glass;
however, we do not see an image from the other side because molecules in
the milk are scattering the photons as they pass through the solution. The
dye in a red tablecloth is absorbing wavelengths in the blue, green, yellow,
and orange regions, while reﬂecting back photons with wavelengths in the
red region. Similarly, the dye in a blue plate is absorbing wavelengths in the
red, orange, yellow, and green regions, while reﬂecting back wavelengths in
the blue region. This phenomenon is not limited to the range of the optical
detectors of our eye; it occurs across the electromagnetic spectrum and is the
basis for many technologies.

Tissues are heterogeneous substances that contain a variety of compo-

nents that vary between tissue types and may even vary within the structure
of the tissue. The optical properties of a tissue are inﬂuenced by the optical
properties of its component substances and the concentration and distribu-
tion of those substances within the tissue. While visible light is transmitted
through cornea and lens, it is reﬂected by tapetum and is absorbed by retinal
tissue. Although teeth appear white and homogeneous because they reﬂect
visible light, the optical properties in the visible and IR regions diﬀer sub-
stantially among the enamel, dentin, and pulp regions because of the diﬀer-
ences in their composition.

The principal components of biologic tissue that have received the most

attention in regard to their inﬂuence on light in the UV through IR regions
are water, hemoglobin, and melanin. Recently, increased attention has also
been devoted to understanding the roles of collagen, hydroxyapatites, and
lipids. For the clinician, the ﬁrst criterion for selecting a laser is to choose a
wavelength that will be maximally absorbed by the components of the target
tissue or compound (Fig. 3).

Mechanisms of action [1,6–10]

The mechanism of tissue disruption by laser energy may be photother-

mal, photoablative, photodisruptive (photomechanical or plasma induced),
or photochemical. For most surgical laser systems the primary inﬂuence on
tissue is photothermal. This inﬂuence results from the absorption of photons
in tissue, conversion to thermal energy, and the resultant alteration in tissue
induced by the thermal change.

Photoablation is the process of tissue decomposition from bond breaking

that results from direct absorption of photons, without a thermal inﬂuence.
This mechanism is induced by UV wavelengths and is used commonly for
corneal sculpting. The mechanism of photoablation should not be confused

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G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

Fig. 3. The absorption coeﬃcients (l

) for water [11], hemoglobin [12], and melanin (skin) [13]

have been calculated and plotted for wavelengths (k) in the visible to infrared region and
compared with speciﬁc clinical laser systems. The coeﬃcient values are plotted in log scale as
their values range across eight orders of magnitude. The larger the coeﬃcient value, the better
the wavelength is absorbed by the substance.

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G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

with the more broadly used term ablation, which is frequently used to de-
scribe the removal of tissue by laser energy regardless of mechanism.

Photomechanical disruption of tissue may be induced when high pulse

energies are deposited into tissue in successive pulses of short duration, re-
sulting in the generation of shock waves, cavitation, or jet formation within
the tissue. Laser-induced plasma formation is a type of photodisruption in
which tissue breakdown results from an increase in the local electrical ﬁeld
strength in the tissue, resulting in the ionization of molecules and atoms
(plasma formation). Photochemical mechanisms of tissue alteration are a
result of biochemical reactions in tissue that are induced by the absorption
of photons and are typical of the reactions induced in the application of photo-
dynamic therapy.

Because the photothermal mechanism is the principal mechanism induced

by the lasers currently used in soft tissue surgery, it will be the focus of dis-
cussion in this chapter. As photons are absorbed and thermal energy is gen-
erated, tissue changes result from the degree and distribution of temperature
elevation in the tissue. When tissue temperatures reach 60

to 65C, proteins

are denatured, and tissue necrosis can be expected. When the tissue tempera-
ture reaches 100

C, water in the tissue undergoes a phase transformation,

moving from liquid to steam and increasing interstitial pressure until the
pressure within the tissue exceeds the strength of conﬁnement by the tissue
architecture, resulting in an explosive vaporization. When temperatures
exceed 150

C, proteins are broken down, releasing hydrogen, nitrogen, and

oxygen and leaving carbon behind in a layer of carbonization commonly
referred to as char.

The typical laser ablation produces a tissue crater where vaporization has

occurred, surrounded by zones of thermal injury (Fig. 4). Protein denatura-
tion will result in tissue necrosis when tissue temperatures adjacent to the
vaporization crater have exceeded 60

to 65C but did not reach the

100

C vaporization threshold. When tissue temperatures are elevated but do

not reach 60

C, thermal injury may be present but generally does not result in

tissue necrosis.

Tissue temperature elevations are much greater when photons are well

absorbed and conﬁned to a small volume than when photons are poorly ab-
sorbed and thus both photons and thermal energy are distributed over a
larger area. Reaching the vaporization threshold eﬃciently and eﬀectively
is best achieved by using a wavelength that is well absorbed by the target
tissue. A wavelength poorly absorbed by tissue achieves the ablation thres-
hold with diﬃculty and induces a wider area of subablative thermal injury in
the tissue (Fig. 4).

Water is the most prominent tissue component targeted for beam absorp-

tion in soft tissue cutting and ablative applications. The relatively high water
absorption coeﬃcients of the Er:YAG and CO

laser wavelengths [6,11]

make these lasers the preferred systems for general soft tissue surgery.
Argon, dye, and frequency-doubled near-IR lasers produce wavelengths in

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G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

the blue-green region, which is the preferred absorption region of hemoglo-
bin (absorption peaks 280, 420, 540, and 580 nm [6,12]). Because hemoglobin
content of most tissues is less than the water content, tissue ablation by
hemoglobin targeting wavelengths is generally less eﬃcient and produces a
wider area of thermal injury than is achieved with comparable exposure
to wavelengths that are well absorbed by water. In the near-IR region of
800 to 1500 nm, water, hemoglobin, and melanin are less well absorbed
[6,11–13], making laser wavelengths in this region the least eﬃcient at reaching
vaporization thresholds and producing the widest zones of thermal change in
tissue because of their deeper depth of penetration (Figs. 3, 4).

Because water is a relatively poor absorber of wavelengths in the near-IR

region, tissues that are otherwise poorly pigmented will allow substantial

Fig. 4. When photons of a speciﬁc wavelength are absorbed well by a target tissue, they remain
conﬁned to a small volume of tissue and rapidly raise the internal tissue temperature to the
ablation threshold, thus minimizing collateral thermal injury by photon dispersion (A). When a
wavelength is poorly absorbed by the target tissue and photons are dispersed across a large area
or when a well-absorbed wavelength is delivered in low irradiances, which permit diﬀusion of
thermal energy to surrounding tissues before an ablation threshold is reached, shallower areas
of vaporization and wider areas of collateral thermal injury are produced (B, C). Diagram A is
representative of soft tissue vaporization by an Er:YAG or CO

laser that is well absorbed by

water. Diagram B is representative of soft tissue vaporization by an Er:YAG or CO

laser if a

low power density is applied over a longer time, prolonging the onset of tissue vaporization or is
representative of the use of a less well-absorbed wavelength, such as an Argon or KTP laser.
Diagram C is representative of either an extremely prolonged application of a well-absorbed
wavelength at a very low irradiance or is representative of the use of a poorly absorbed wave-
length, such as one of the near-IR diode or Nd:YAG wavelengths in noncontact application.
Selective photothermolysis (D) uses a wavelength that is transmitted by one tissue to photo-
coagulate an absorbing tissue or structure located within the transmitting tissue.

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G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

transmission and some scattering of these wavelengths. When hemoglobin-
or melanin-containing structures (which are better absorbers of near-IR
wavelengths than water) are located within or beneath otherwise poorly pig-
mented tissue, the hemoglobin or melanin structures will absorb wave-
lengths that are being transmitted through the tissue, resulting in selective
photocoagulation of the pigment containing structures (Fig. 4D) [8,14]. In
humans, wavelength selection based on diﬀerences in the absorption charac-
teristics of tissues is coupled with short pulses and used to selectively photo-
coagulate hemangiomas, birthmarks, pigmented dermal lesions and hair
follicles by a mechanism referred to as selective photothermolysis.

When it is necessary to use a near-IR wavelength for soft tissue surgery,

improved eﬃciency of cutting and reduction of collateral thermal injury
may be achieved by delivery of the beam through a ﬁber that is brought into
contact with the tissue. In this manner the photothermal weakening of the
tissue architecture by the beam is coupled with the mechanical force of the
ﬁber to separate tissue. Delivery ﬁbers may be used with a bare exposed end
or may have sculpted tips that further augment beam dispersion and passage
of the ﬁber through tissue [10].

Energy, power, ﬂuence, and irradiance [1,8,15]

Laser light is typically quantiﬁed in units of energy termed joules (J), and

units of power termed watts (W). Energy is a measure of work and power is
the rate at which work is done (eg, rate at which energy is delivered to tis-
sue). A value of 1 W is equal to the rate of work of 1 J/s. Given a known
power of beam delivery (eg, 10 W) for a known period (eg, 5 seconds), the
total energy delivered can be determined (10 W

5 seconds ¼ 50 J).

The size of the area over which a ﬁxed amount of energy is delivered will

inﬂuence the magnitude of work accomplished within that area. Consider 10
workers building a wall; each worker can lay 50 bricks each per hour and
can work at that rate for 8 hours, laying down 4000 bricks per day. At the
end of the day their wall will be 10 times higher if it is distributed along a 10-ft
distance than if it is distributed along a 100-ft distance, yet the rate of work
and the total energy expended will be the same in each case.

Power density is a measurement of the rate of work within a deﬁned area

and is generally reported as W/cm

, with the area being deﬁned by the beam

spot size (r

) at the tissue surface. Similarly, energy density is a measurement

of the total work accomplished within a deﬁned area and is generally
reported as J/cm

. Power density is also referred to as irradiance, and energy

density may be referred to as ﬂuence.

The rate and total amount of laser energy deposited into tissue will have

an inﬂuence on the tissue eﬀect produced by the wavelength. For the 10,600
nm CO

wavelength directed onto soft tissue, a power density of 1200 to

1500 W/cm

is required to induce tissue ablation. If 20 W of laser power

is directed toward the tissue within a 2-mm beam diameter, the incident

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G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

power density (irradiance) is 636 W/cm

, an insuﬃcient rate to induce

vaporization. If that same 20 W is directed onto the tissue in a 1-mm beam
diameter, the incident power density is 2500 W/cm

, and ablation is easily

achieved.

For each increment in which the beam diameter changes by a factor of

two, the incident power density will change by a factor of four. Where 10 W
is delivered in a beam diameter of 0.8 mm, the power density will be ap-
proximately 2000 W/cm

. For the same 10 W delivered in a spot size of 0.4 mm

the power density will be approximately 8000 W/cm

and with a spot size of

0.2 mm it will be 32,000 W/cm

(Fig. 5). Although the wavelength and

power output of the laser remains the same in each case, changing the spot
size of the beam produces tremendous diﬀerences in power density and the
inﬂuence on tissue.

Beam delivery through a lens focuses a collimated beam of laser light into

a focal spot, producing a beam that narrows in diameter from the lens to the
focal point and then widens in diameter as the photons cross in their paths
of travel and diverge away from the focal point. The variable diameter of the
converging and diverging aspects of the focused beam results in a range of
power densities that are available to the surgeon without having to change
the power output of the laser. By moving the handpiece of the laser so that
the tissue surface is in the focal plane of the lens (focused) or out of the focal
plane (defocused), the power density delivered to the tissue can be controlled
and dramatically altered by the surgeon (Fig. 5). Similar eﬀects are achieved
when the beam exits a ﬁber or waveguide tip where no lens is present. The
photons are concentrated at the point of exit and diverge as they move away
from the ﬁber or waveguide tip.

Fig. 5. The area over which photons are distributed inﬂuences their concentration and the rate
at which energy is deposited into tissue. The beam may be delivered through a lens (A) that
focuses the beam into a spot or may be delivered through a ﬁber or waveguide (B), where the
beam exits a through tip or ﬁber end.

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G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

Beam proﬁle [1–3,5,15]

The distribution of photons across the beam (beam proﬁle) will inﬂuence

the spatial distribution of those photons as they are launched into tissue,
and this distribution will inﬂuence the character of their eﬀect on the tissue.
When a power meter is used to measure beam power, the value given is for
the beam as a whole. When the concentration of photons within the beam is
either higher or lower than that measured for the beam as a whole, the
power density within the beam proﬁle will be higher or lower and that vari-
ability may become manifest in the eﬀect of the beam on tissue, especially on
the character of an ablation crater if ablative powers are being used.

The distribution of photons across a beam is rarely uniform. The typical

distribution is gaussian; a bell-shaped distribution with the highest con-
centration of photons in the center of the beam tapering to a lower concen-
tration on the beam periphery. A gaussian proﬁle is a transverse electric and
magnetic (TEM

) mode conﬁguration and generally produces a cone-shaped

ablation crater in tissue. When two gaussian peaks are present in the beam
proﬁle, the distribution is referred to as TEM

; when multiple peaks are

present within the beam proﬁle, the distribution is referred to as TEM

. The

vaporization crater produced by a beam with a TEM

proﬁle has a ﬂat-

ter contour to its base and (assuming all other exposure parameters are the
same) is likely to be shallower than the crater produced by the TEM

beam

conﬁguration (Fig. 6).

Fig. 6. The beam proﬁle represents the distribution of photons across the width of the beam
and is rarely uniform. A TEM

distribution is gaussian and produces a cone-shaped crater in

tissue. The TEM

distribution has two gaussian peaks and produces a crater with a central

ridge. With a TEM

distribution, multiple peaks are present across the beam, resulting in a

crater with a ﬂat contour to its base.

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G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

Time domains of energy delivery [1,6,8–10,16,17]

While photon distribution and absorption will inﬂuence the thermal

energy content of tissue, the diﬀusion of heat through tissue will also inﬂu-
ence the temperature gradients produced within tissue and contribute to the
overall eﬀect of the laser. Thermal energy seeks equilibrium, diﬀusing from
areas of high temperature to areas of lower temperature. An example of this
principle is observed when we hold a steel rod at one end and heat the other
end in a ﬂame. Just as heat from one end of the rod travels to the other end
until the whole rod becomes too hot to hold, heat diﬀuses through tissue from
a point of high energy content to surrounding areas of lower energy content.

The magnitude of thermal diﬀusion from the surgery site can be inﬂuenced

by both the surgeon and by the mode of laser beam delivery. Surgeons with a
low level of experience and comfort with use of a surgical laser typically select
lower power settings and larger spot sizes to keep incision and ablation rates
at a comfortably slower rate than are likely to be used by the more experi-
enced surgeon. By taking more time to deposit the energy needed to accom-
plish a procedure, the beginning surgeon also is allowing more time for
thermal energy to diﬀuse and accumulate in surrounding tissue (Fig. 4).

Before the total energy content of tissue at the ablation site reaches the

ablation threshold, the accumulating thermal energy has an opportunity
to diﬀuse to surrounding tissue. Once the vaporization threshold of the tar-
get tissue is reached (100

C), a plume of steam and debris is ejected from the

ablation site, carrying with it much of the thermal energy accumulated within
the site. The longer the time interval used to deliver suﬃcient energy into the
tissue to reach the ablation threshold, the greater the opportunity for diﬀusion
of thermal energy from the ablation site to adjacent tissue.

If the amount of energy required to reach the ablation threshold in tissue

can be delivered in pulses that are shorter than the time required for thermal
diﬀusion, then individual ablation events can be generated without enough
heat transfer to aﬀect adjacent tissue. The length of this pulse must be shorter
than the thermal relaxation time of tissue; a calculated value that is depen-
dent on both the tissue absorbance of the incident wavelength and the ther-
mal diﬀusion time of the tissue (Fig. 7). Although the thermal relaxation
time is wavelength dependent, the shortest time considered for tissue is 1
l

s (10

-6

seconds) as calculated for the 3000 nm wavelength absorption peak

of water. This ﬁnding has led to the generalized rule of thumb (frequently
referred to as the ‘‘1 microsecond rule’’) that pulses less than 1 ls in duration
will not be associated with collateral thermal injury. Although the thermal
relaxation time of a tissue actually may be longer than 1 ls (depending on
incident wavelength and the optical and thermal properties of a speciﬁc tis-
sue), it is generally in the microsecond domain, extending into millisecond
durations for larger structures, such as blood vessels and hair follicles. For
the 10,600 nm CO

laser, the thermal relaxation time for soft tissue has been

calculated to be between 300 and 700 ls.

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G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

Beam delivery modes [1,3,6,8]

Lasers may be operated in either continuous wave (CW) or pulsed modes

(Fig. 8). When a laser is operating in CW mode, the shutter remains open,
and the laser beam is released continuously during activation. The power
setting reﬂects the actual power release of the laser. Thermal energy accumu-
lates in tissue as a function of exposure as controlled by the surgeon.

When the laser is set to a pulsed mode, the laser beam is released in

repeated bursts of a speciﬁed pulse length (duration) and repetition rate (fre-
quency). Typically, the pulse durations for surgical lasers are in the milli-
second range; however, some laser systems, especially those designed to
induce photodisruptive rather than thermal mechanisms, may produce
nanosecond (10

-9

seconds) to femtosecond (10

-15

seconds) domain pulses.

The pulse repetition rate is given in units of pulses per second termed Hertz
(Hz) or may be speciﬁed as a unit of time between the onset of consecutive
pulses (pulse interval). While millisecond pulse durations are longer than the
thermal relaxation time of tissue, pulsing the beam delivery allows the sur-
geon to deposit higher powers into tissue with more control, and, depending
on the length of the pulse interval, may allow tissue cooling between pulses
to reduce heat accumulation and diﬀusion.

When the beam is delivered in a pulse mode, energy will be released

throughout the pulse at a speciﬁc rate (pulse power or peak power); how-
ever, because there are intervals between pulses where no energy is being
released, the average rate of energy delivery (average power) over an expo-
sure period will be less than the power delivered within any single pulse. If a
laser is set to deliver pulses of 10-ms duration each, 0.1 J each, at 60 Hz,
the average power of each pulse will be 10 W (ie, 0.1 J/10

-3

seconds);

however, this setting delivers a total of 6 J over every 1 second of exposure
(ie, 0.1 J/pulse

60 pulses/s), so the average power delivered to the tissue by

Fig. 7. Osteotomy of cortical bone performed using a free electron laser. Wavelength, pulse
energy, spot size, pulse frequency, and speed of passage of beam over the site were the same for
both specimens. Specimen A reveals a shallow, wide, heavily charred cut with collateral thermal
damage of 80 to 100 lm where the 2.5 ms (10

-3

seconds) macropulse was longer than the

anticipated 50 ls (10

-6

seconds) thermal relaxation time. Specimen B reveals a deep, narrow cut

with no char and with less than 10 lm of collateral thermal injury when the pulse energy was
delivered within a 4.0 ls macropulse, which is shorter than the tissue thermal relaxation time.

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G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

the laser is 6 W (ie, 6 J/1 s). Because the rate of work during each pulse will
be at 10 W, it is important to diﬀerentiate between the power of the indivi-
dual pulse and the average power of the beam as delivered to tissue.

The pulse of a laser may have speciﬁc characteristics relating to the rate

that energy is released within the pulse duration, and this is referred to as the
pulse structure (Fig. 9). The rate of energy release (power) may remain con-
stant or may vary in intensity within the duration of a single pulse. When the
power level varies within a pulse, it may jump to a peak and taper down
(tail); it may increase to a peak and then decrease; or it may increase to a
peak and stop. To characterize the pulse structure, in addition to the
pulse duration and frequency, the average power delivered during the pulse

Fig. 8. In CW mode, when the laser shutter is activated, it remains open, and photons are
released continuously at a preset rate (power) until the shutter is closed. The rate of energy
release is the power setting of the laser, and both the peak power released and the average power
delivered to tissue are the same. When a pulsed mode is used, the photons are released in
predetermined amounts (pulse energy) over a predetermined period of time (pulse length or
duration) at speciﬁed intervals (pulse interval or frequency). The highest rate of photon (energy)
release during the pulse is the peak power. The average power delivered to tissue is the pulse
energy divided by the pulse interval (W

¼ J/s), which reﬂects an average of the energy delivered

during a pulse and the absence of energy delivery between pulses. Although the pulse energy
and peak power delivered by the laser may remain the same, the average power delivered to
tissue changes when the interval between pulses is changed. Superpulse mode allows the delivery
of very high peak power pulses in very short pulse lengths, which may be released in a con-
tinuous stream of micropulses or in bursts of micropulses for speciﬁed durations (macropulses)
at speciﬁc intervals (frequency).

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G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

duration and the highest power generated within the pulse (peak power) are
important considerations.

If a 10-ms pulse has an average power of 10 W (ie, 10 J/s), 0.1 J is deliv-

ered by the pulse (pulse energy

¼ 10 J/s 10 10

-3

¼ 1 10

-1

J). If the

energy is delivered at a constant rate throughout the pulse duration, then the
average power of the pulse, and the peak power of the pulse are the same:
10 W. If during the pulse duration the total energy delivered remains the
same, but the rate of energy delivery (power) increases, peaks, and declines,
such that 80% of the energy (ie, 0.08 J) is delivered within 10% of the pulse
duration (ie, 1 ms), the peak power for the pulse will be 80 W (ie, 8

-2

J/1

-3

seconds). In one case we have a 10-W pulse with a 10-W peak

power; in the second case we have a 10-W pulse with an 80-W peak power.

The superpulse mode of a laser capitalizes on the release of very high

peak power pulses in short durations (typically in the microsecond range)
to achieve eﬃcient tissue ablation with reduced thermal transfer to adjacent
tissue (Fig. 8). With the superpulse mode, an average power of 10 W can be
delivered to tissue by the laser, but delivered in a succession of 800-ls pulses,
delivered at 200 Hz, each with a peak power of 50 W. The superpulse mode
can be operated in a continuous release of individual superpulses or can be

Fig. 9. Pulse structure is characterized by the rate of energy release over the duration of the
pulse and includes both peak power and pulse length. When a laser pulse is generated by the
application of pulsed energy to the lasing medium, such as with a pulsed dye laser, there is a
sloping gain to peak power and subsequent decay of power during each pulse (A). When power
varies during the pulse in a uniform manner (increases and decreases at the same rate), the pulse
length may be expressed as an average rate of energy release by determining the pulse duration
at the point where half of the maximum pulse intensity is present, rather than measuring from
the onset to end of energy release. This is referred to as measuring the pulse at full width half
maximum (FWHM). When power varies within a pulse, the total pulse energy divided by the
pulse length may be reported as the average pulse power. When a pulse is created by the
controlled release of photons from a laser, such as by the opening and closing of a shutter for a
speciﬁed time, the gain and decay of the pulse power are almost immediate, and the pulse length
at FWHM is almost identical to the length measured from onset to end of energy release (B).
When the gain and decay of the pulse power are not uniform, such as with the pulse of a TEA
CO

laser, where an initial 100 to 200 ns gain is followed by a 1 to 4 ls tail (C), the pulse length

is generally reported from the onset to end of energy release, with more detailed char-
acterization of the parameters of the gain and decay of the pulse power.

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G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

released as a continuous stream of pulses for a speciﬁed time at speciﬁed
intervals. The superpulse mode lets the surgeon (1) deposit pulses of very
high peak power into tissue with control, (2) conﬁne the exposure to pulse
durations that approximate the thermal relaxation time of the tissue, and
(3) use pulse repetition rates with intervals that allow tissue cooling between
pulses to reduce heat accumulation in tissue. Heat accumulation also can be
prevented at repetition rates faster than the cooling rate of tissue when the
delivery mode is used in combination with a computer-controlled beam
delivery device, such as a scanner or pattern generator, that directs successive
pulses at diﬀerent locations within a predetermined pattern.

Light dosimetry for photodynamic therapy
and nonablative applications [7,18,19]

In nonablative applications of laser light, such as to excite photosensitiz-

ing compounds in tissue for photodynamic therapy (see Chapter 11) or to
evaluate the legitimacy of biostimulation, it is important to understand the
distribution of light in tissue to predict energy deposition and the adequacy
of exposure. As already discussed, the distance and course that photons
travel into tissue depends on both the wavelength of the incident photons
and the optical properties of the tissue as inﬂuenced by the composition and
concentration of compounds within the tissue that will scatter or absorb the
speciﬁc wavelength.

The depth of penetration (d) of a given wavelength is the distance trav-

eled by photons within the tissue when the beam intensity drops by 63%.
This may be expressed in increments, with the depth of each increment
representing an additional 63% decay in power. Thus, within two incre-
ments, the intensity drops by 87% and has decayed by 95% by the time three
penetration depths have been reached.

The penetration depth does not necessarily correspond to the eﬀective

treatment depth but may be used to predict an anticipated eﬀective treat-
ment depth if an energy threshold for response is known. For example, if the
ﬂuence applied is 100 J/cm

and the threshold for response requires 50 J/cm

then the eﬀective treatment depth will be less than one d where the internal
exposure would be 37 J/cm

. On the other hand, if the surface ﬂuence is 100

J/cm

and the response threshold requires 13 J/cm

, the eﬀective therapeutic

depth would be expected at two increments of d.

In addition to the optical properties of the tissue, the geometry of the

incident beam will aﬀect the ﬂuence-depth distribution of energy within the
tissue. As photons move into tissue and scattering events occur, in the center
of the beam there is a fairly high probability that a photon that is scattered
in one direction will be replaced by an adjacent photon that has also under-
gone a scattering event. On the periphery of the beam, however, the number
of adjacent photons is decreased (or absent outside of the beam diameter),

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G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

reducing the probability that a scattered photon on the periphery of the
beam will be replaced by an adjacent scattering event. The ﬂuence distribu-
tion within the tissue produces a pattern where the distribution is initially
wider than the incident beam diameter because of photon scattering away
from the beam and demonstrates more rapid decay on the periphery than
in the center of the area of exposure. As the incident spot size increases, a
higher percentage of photons remain located within the ﬁeld of the primary
beam after each scattering event. The result is that for the same incident
power density, with increasing spot size up to a diameter of approximately
4d, the ﬂuence depth increases.

In addition to forward and lateral travel, photon-scattering events within

the tissue can be in a reverse direction. As a result, the tissue surface is sub-
jected to photons of both the incident laser beam and those being scattered
back from the interior of the tissue (internal reﬂectance). This phenomenon
of both incident irradiance and internal reﬂectance creates a total power
density at the surface of the tissue that is greater than the irradiance of the
laser beam itself. Because incident power densities of 150 to 200 mW/cm

are

associated with temperature increases of 5

to 7C, power densities below

150 mW/cm

are commonly used in subablative procedures to prevent

thermal injury.

For wavelengths between 600 and 900 nm that penetrate most deeply into

soft tissue, the optical penetration depth d in nonmelanotic tissue is 3 to 5 mm.
If we assume the maximum d

¼ 5 mm and the use of a 2 cm (ie, 4d) incident spot

diameter, the power density at the center of the beam 5 mm into tissue will be
55.5 mW/cm

. At 1-cm depth, the power density will be 20.5 mW/cm

, and by

2 cm will be reduced to 7.5 mW/cm

. If the tissue contains melanin, the optical

penetration depth is reduced to 1 to 2 mm, resulting in an internal irradiance of
7.5 mW/cm

at a depth of 4 mm instead of the 2 cm anticipated for the non-

melanotic tissue. Although increasing the duration of tissue exposure at a
given power density will increase the total energy deposited at a depth within
the tissue, a greater increase in energy deposition will occur at the tissue
surface, and this may provide an upper limit to which a treatment exposure
can be made without unwanted tissue injury (Fig. 10).

Scientiﬁc reporting and critical thinking

As has been explored in this chapter, in addition to wavelength selection,

many other aspects of a laser application will inﬂuence the outcome of the
irradiation. To assess the strengths and weaknesses of applications, adjust
parameters to improve results, predict potential problems before attempting
an application, and compare information between studies and reports; and
for an individual to be able to repeat an application of laser energy to tissue
in a manner similar to that reported by someone else, the minimum amount
of information required should include laser wavelength, power, beam spot

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G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

size on application, delivery mode, mechanism of delivery, and duration of
exposure, and this information should be included in any case report or pub-
lication. If mode of delivery is a pulsed form, then the parameters of the pulse
structure should be reported, including pulse duration, pulse energy or aver-
age pulse power, peak power, and either pulse frequency or pulse interval.

It is important to report the method of beam delivery (optical ﬁber, wave-

guide, or articulated arm). If delivered through a ﬁber, the ﬁber material and
ﬁber diameter should be reported, and the application should be noted as
either in contact or noncontact delivery. When the beam is applied through
a tip, the tip diameter and composition should be reported. Where the beam
is directed through a lens, then that should be noted, and the importance of de-
scribing the beam proﬁle (eg, TEM

, TEM

) should be considered.

By being inclusive of all of these parameters in reporting and thinking, laser
surgeons will be better able to evaluate, modify, and validate applications.

References

[1] Berns MW, Nelson JS, Wright WH. Laser physics and laser-tissue interactions.In:

Achauer BM, Vander Kam VM, Berns MW, editors. Lasers in plastic surgery. New York:
Thieme Medical Publishers, Inc.; 1992.

Fig. 10. When the optical properties of the tissue are known for the incident wavelength, the
distribution of irradiance and ﬂuence within the tissue can be predicted. The point in tissue
where the incident beam has decreased by 63% is referred to as the optical penetration depth (d).
For each subsequent distance d, the beam will decrease by an additional 63%. For the same
wavelength and tissue, d will increase as the diameter of the beam increases up to a diameter of
4d. When the irradiance (power density) and length of exposure are known, the ﬂuence (energy
density) delivered to the tissue can be plotted. Where 150 mW/cm

has been administered for

16.7 minutes (1000 seconds), 150 J/cm

will have been delivered to the tissue. The ﬂuence at the

surface of the tissue will be greater than the incident ﬂuence because of internal reﬂectance.
A plot of the internal ﬂuence illustrates that if an event requires a threshold level of energy
‡55.5 J/cm

it will only occur within the region of 1d, within 2d if

‡20.5 J/cm

is required and

within 3d if it requires

‡7.6 J/cm

. If photosensitizer in a tumor (T) were to require a minimum

of 55.5 J/cm

to kill tumor cells, the beam conﬁguration in A would not be successful in

eliminating the entire tumor, whereas the conﬁguration in B would be more likely to be eﬀective.

533

G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

[2] Hecht J. The laser guidebook. 2nd edition. New York: McGraw-Hill Inc.; 1992.
[3] Hitz CB. Understanding laser technology. Tulsa (OK): Penn-Well Press; 1985.
[4] Siegman AE. Lasers. Sausalito (CA): University Science Books; 1986.
[5] Silfvast WT. Laser fundamentals. Cambridge: Cambridge University Press; 1996.
[6] Boulnois JL. Photophysical processes in recent medical laser developments: a review. Lasers

Surg Med 1986;1:47–66.

[7] Jacques SL. Laser-tissue interactions—photochemical, photothermal, and photomechani-

cal. Surg Clin North Am 1992;72:531–58.

[8] Niemz MH. Laser–tissue interactions fundamentals and applications. Berlin: Springer-

Verlag; 1996.

[9] Venugopalan V, Nishioka N, Mikic B. The eﬀect of laser parameters on the zone of ther-

mal injury produced by laser ablation of biological tissue. ASME J Biomech Eng 1994;116:
62–70.

[10] Welch AJ, van Gemert MJC, editors. Optical-thermal response of laser-irradiated tissue.

New York: Plenum Press; 1995.

[11] Hale GM, Querry MR. Optical constants of water in the 200-nm to 200-lm wavelength

region. Appl Opt 1973;12:555–63.

[12] Prahl S. Tabulated molecular extension coeﬃcient for hemoglobin in water. Available at:

http://omlc.ogi.edu/spectra/hemoglobin/summary.html. Accessed June 20, 2001.

[13] Jacques SL, McAuliﬀe DJ. The melanosome:threshold temperature for explosive vapori-

zation and internal absorption coeﬃcient during pulsed laser irradiation. Photochem Photo-
biol 1991;53:769–75.

[14] Anderson RR, Parrish JA. Selective photothermolysis: precise microsurgery by selective

absorption. Science 1983;220:524–7.

[15] Fisher JC. The power density of a surgical laser beam: its meaning and measurement.

Lasers Surg Med 1983;2:301–15.

[16] van Gemert MJC, Welch AJ. Time constants in thermal laser medicine. Lasers Surg Med

1989;9:405–21.

[17] Walsh JT, Flotte TJ, Anderson RR, et al. Pulsed CO

laser tissue ablation: eﬀect of tissue

type and pulse duration on thermal damage. Lasers Surg Med 1988;8:108–18.

[18] Svaasand LO, Potter WR. The implications of photobleaching for photodynamic therapy.

In: Henderson BW, Dougherty TJ, editors. Photodynamic therapy, basic principles and
clinical applications. New York: Marcel Dekker, Inc; 1992.

[19] Wilson BC, Patterson MS. Light delivery and optical dosimetry in photodynamic therapy

of solid tumors. In: Henderson BW, Dougherty TJ, editors. Photodynamic therapy, basic
principles and clinical applications. New York: Marcel Dekker, Inc.; 1992.

534

G.M. Peavy / Vet Clin Small Anim 32 (2002) 517–534

Laser safety

Thomas R. Fry, DVM, MS

Cascade Veterinary Specialists, 660 NW Gilman Blvd.,

Suite C-2, Issaquah, WA 98027, USA

Discussion of laser safety is essential in light of the burgeoning use of

lasers in veterinary medicine over the past two decades. Many veterinarians,
including new graduates, have had little or no training concerning the safe
use of lasers. The curricula of most veterinary schools up until the last sev-
eral years often did not cover this topic. Veterinarians may ﬁnd themselves
using this new technology after very limited exposure in weekend short-
courses with a minimum of hands-on experience. Most of the hazards asso-
ciated with improper use of lasers are easily covered in a brief review of
safety principles, which is the intent of this article.

The deﬁnitive documents for outlining the safe use of lasers in veterinary

medicine is the American National Standards Institutes (ANSI) documents
ANSI 136.3 [1] and ANSI 136.1 [2]. ANSI is a private organization that
develops standards for the safe use of lasers in industry and medicine by con-
sultation with acknowledged experts. ANSI guidelines represent general
agreement among manufacturers, sales personnel, and users regarding the
best current practices [3]. ANSI 136.3 addresses the safe use of lasers in
human health care facilities, whereas ANSI 136.1 covers the much broader
topic of laser safety. These standards are guidelines, not regulations, for the
safe use of laser systems in human health care facilities. At present, neither
document mentions veterinarians or veterinary medicine speciﬁcally; how-
ever, it is reasonable to assume that the Occupational Safety and Health
Administration (OSHA) [4] or state regulatory agencies will use these same
guidelines as safety issues arise in veterinary medicine. The fact that veteri-
narians are not speciﬁcally mentioned should not be considered an invitation
to invent substandard safety practices or disregard safety standards al-
together. Veterinarians must be proactive and provide the safest possible
laser use. As a side note, both of these laser safety documents are under
review, and it is highly likely that new versions due for publication in 2001,
will address veterinary medicine in either the main text or in appendices.

Additional federal regulations concerning lasers as medical devices are

under the authority of the Food and Drug Administration Center for Devices

Vet Clin Small Anim 32 (2002) 535–547

0195-5616/02/$ - see front matter

PII: S 0 1 9 5 - 5 6 1 6 ( 0 2 ) 0 0 0 0 4 - 9

and Radiological Health via enforcement of the Federal Laser Product per-
formance Standard and the Medical Devices Amendment to the Food, Drug,
and Cosmetic Act [2]. All laser products sold in the United States since
August 1976 must be certiﬁed by the manufacturer as meeting safety stan-
dards, and each laser must bear a label indicating compliance with the
standards and listing the laser hazard classiﬁcation (class I to IV) [5].

Laser hazard classiﬁcation

Lasers are subdivided into four classes, depending on their ability to inﬂict

damage to skin or eyes. Class I lasers do not emit laser radiation greater than
the maximum permissible level (MPE) and are not harmful for direct viewing
or skin contact. MPE is deﬁned as the maximum laser radiation exposure
without adverse biologic eﬀects to the eye or skin [6]. An example of a class
I laser is a grocery store scanner. Class II lasers are in the visible light spectrum
and are not harmful for momentary viewing. Longer viewing times are usually
not possible because of a normal aversion (blink) response [7]. Although laser
pointers (helium-neon) are class II lasers, they may be harmful if the MPE is
exceeded by staring into the beam. Class III lasers are harmful for direct view-
ing, and an example would be the lasers used in laser light shows. Class IV
lasers are any laser with power greater than 0.5 W over 0.25 seconds or those
that exceed a ﬂuence of 10 J/cm

[8]. Almost all surgical lasers fall in this cate-

gory. Direct, reﬂected, and diﬀusely reﬂected beams of class IV lasers may
injure the eye or skin. Additionally, most class IV lasers pose ﬁre hazards [9].

Beam-related hazards

Primary hazard assessment of laser use in medicine concerns ocular and

skin exposures. MPE values have been calculated based on laser wavelength
for both skin and eye exposures [1]. MPE does represent a maximum expo-
sure, and every attempt should be made to minimize exposures for obvious
reasons. MPE levels are dependent on wavelength, exposure time, and pulse
repetition. Values are expressed in either radiant exposure (joules/square
centimeter) also known as ﬂuence; or as irradiance (watts/square centimeter)
also called power density. Values for each laser are published in the ANSI
documents [1,2]. Any value higher than the MPE does cause tissue damage
[10]. In general, the longer the wavelength of the laser, the higher the MPE,
and the longer the exposure time, the lower the MPE [2,10].

Ocular hazards

Ocular hazards include corneal and lenticular opacities, as well as retinal

damage; all of which are dependent on laser wavelength. Although some

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T.R. Fry / Vet Clin Small Anim 32 (2002) 535–547

forms of corneal damage may be reversible, cataract formation and retinal
injuries are not [11]. Other factors that aﬀect the amount and type of tissue
damage include tissue volume, beam energy, and length of lasing [6].

The following example illustrates why the eye is at extreme injury risk from

laser energy. A 1-W visible laser beam is an inﬁnitely greater hazard to the
retina than a 100-W incandescent light bulb. The brightness of the collimated
laser beam is more than one billion times greater than the light bulb [12].

Visible wavelength energy (400 to 780 nm) and near infrared (IR-A, 780

to 1400 nm) will pass through the cornea and lens and directly induce ther-
mal damage to the retina, causing loss of color vision, night blindness, and
potentially complete loss of vision [13]. As a result, visible and near-IR
wavelengths are known as the retinal hazard region. Neodymium:yttrium-
aluminum-garnet (Nd:YAG) and diode lasers, which are commonly used
in veterinary medicine, may induce retinal damage resulting in decreased
or lost vision. This damage is increased with longer duration exposures and
pupillary dilation.

Near ultraviolet (UV-A) wavelengths (315 to 400 nm) pass through the

cornea and are absorbed by the lens, resulting in photochemical denatura-
tion of lens proteins, which causes cataract formation [9,11,13]. Far UV
(UV-B, UV-C) wavelength energy (100 to 315 nm) will be absorbed by cor-
neal epithelium, resulting in photokeratitis because of denaturation of
corneal proteins [11,13]. Conjunctivitis is also a possible result. Keratitis and
conjunctivitis may be rapidly reversible. Far-IR (IR-B, IR-C) wavelengths
in the 1400 nm to 1.0

nm range will result in corneal damage because

of tissue water absorption, leading to protein denaturation on the corneal
surface. Corneal opacity may develop after this injury. Carbon dioxide
(CO

) lasers are very capable of causing this injury. Wavelengths from

1400 to 3000 nm may penetrate deeper and may cause cataracts as a result
of lens proteins being heated [13]. Minimal temperature rise is necessary for
these changes to occur.

Skin hazards

Far UV radiation (UV-B, UV-C) is also called the actinic UV zone. Ex-

posures may result in erythema or blistering of skin because of epidermal
absorption. A common source of UV-B is sunlight, which has been implicated
in skin carcinogenesis [6]. Similar skin eﬀects may occur in all regions of the
IR spectrum (IR-A, IR-B, IR-C), in addition to hyperpigmentation, photo-
sensitization, and in extreme exposures, charring [13].

Hazard prevention

Without being trite, the simplest way to prevent beam hazards is to pre-

vent the laser beams from contacting with one’s self or with other mem-
bers of the surgical team. Laser surgical procedures need to be performed

537

T.R. Fry / Vet Clin Small Anim 32 (2002) 535–547

exclusively in an operating room or other room speciﬁcally designated for
those purposes. As tempting as it may be, use of lasers in examination
rooms, treatment areas, or wards is inappropriate. Too many variables exist
in these environments for the laser to be used safely, regardless of wave-
length. The concept of the nominal hazard zone (NHZ) is used by ANSI
as a guide to isolating the laser’s eﬀects from trained or casual observers.
NHZ is the space within the level of direct, reﬂected, or scattered radiation
during normal operation that exceeds the applicable MPE [2]. For practical
purposes, ANSI considers the NHZ to be the room in which the procedure
is performed, especially when the laser beam may be freely moved within the
surgical ﬁeld [2].

Other concerns for operating rooms with laser systems include appropri-

ate warning signs on entryways in accordance with the Federal Laser Prod-
uct Performance Standard [1,2]. All class IV lasers must have a warning
sign that states the following: (1) Laser Radiation—Avoid Eye or Skin
Exposure to Direct or Scattered Radiation; (2) a statement of ‘‘laser surgery
in progress—eye protection required’’; (3) the type of laser or the emitted
wavelength, pulse duration, and maximum output; and (4) the class of laser
being used [1,2,9]. An example of an appropriate warning sign is seen in
Fig. 1. The windows and doors in laser operating rooms must be covered
with appropriate materials to contain the NHZ within the room. CO

laser

radiation is easily contained by conventional glass in operating room doors;
however, Nd:YAG or diode radiation requires that windows be covered or
ﬁtted with appropriate ﬁlters. Door interlocks and warning lights may also
be considered in operating rooms that house laser systems [14].

Fig. 1. A typical class IV laser warning sign that should be posted on the operating room door
whenever a laser is in use.

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T.R. Fry / Vet Clin Small Anim 32 (2002) 535–547

Eye and skin hazard prevention

Eye hazards can be prevented by using wavelength-speciﬁc eyewear. Eye-

wear is of no use, however, if it is not worn. Following is a quotation from a
now vision-impaired researcher who viewed the reﬂected beam of a Nd:
YAG laser without protective eyewear.

‘‘When the beam struck my eye, I heard a distinct popping sound caused by
a laser-induced explosion at the back of my eyeball. My vision was ob-
scured almost immediately by streams of blood ﬂoating in the vitreous hu-
mor. It was like viewing the world through a round ﬁsh bowl full of glycerol
into which a quart of blood and a handful of black pepper have been par-
tially mixed.’’ Dr. C.D. Decker [13]

Seventy percent of laser accidents in the United States from 1964 to 1992

involved eye injuries, and 22% were caused by no use or improper use of
protective eyewear [13].

All personnel within the NHZ must wear wavelength-speciﬁc goggles,

spectacles, wraps, or faceshields [10]. Prescription eyeglasses coated with spe-
cial ﬁlter materials, reﬂective coatings, or both may also be acceptable [1,2].
The optical density of the eyewear determines what wavelengths of laser
radiation are attenuated. It is for this reason that there is no universal protec-
tive eyewear [2,10,13,15]. Each laser type will require a diﬀerent set of eye pro-
tection. Color coding of frames with the optical density of the glass or plastic
imprinted on the side of each type of wavelength-speciﬁc eyewear is one
method to avoid confusion and mixing of protective devices [10] (Fig. 2).
As an example, the glass in standard eyeglasses may attenuate CO

laser

radiation, but will not impede radiation from Nd:YAG, diode, or KTP

Fig. 2. Wavelength-speciﬁc eyeware must be worn by all personnel during laser surgical
procedures.

539

T.R. Fry / Vet Clin Small Anim 32 (2002) 535–547

lasers. Additional studies have shown that some types of standard eyeglass
lenses may shatter if exposed to high-intensity (>50 W) CO

beams [15]. As

an additional note of warning, regular eyeglasses without side shields are
unacceptable protective equipment when using CO

lasers; therefore, stan-

dard eyeglasses have no role as personal protective equipment. When using
laser ﬁbers through endoscopes, special ﬁlters need to be used for direct view-
ing or closed circuit monitors need to be used to avoid laser ‘‘ﬂash back’’
through the optical pathway [2,15]. Maintenance of eyewear is an easily over-
looked responsibility. All eyewear needs routine cleaning and inspection, and
in the event of pitting, cracking, or discoloration, it should be discarded and
replaced [2].

Patient eye protection is also essential. Potential options for shielding

include saline-moistened sponges, wavelength-speciﬁc laser eyeshields, or
corneal shields (Fig. 3). A wide array of commercial products is available.

Another potential ocular risk that is as critical as direct eye contact with

the beam is specular (mirror like) and diﬀuse reﬂection of laser radiation.
Specular reﬂections may reﬂect up to 100% of the beam’s energy and there-
fore have the potential to severely damage ocular or any other adjacent tis-
sue. Diﬀuse reﬂections occur when surface irregularity scatters laser light in
all directions, and these are of less risk than specular reﬂection [13]. A pri-
mary concern within the surgical ﬁeld is the highly polished metallic surfaces
of surgical instruments, which maximize the chance of specular reﬂection.
Instruments should be shielded from the beam with moistened sponges or
drapes or the surface of the instrument may be modiﬁed to prevent such
reﬂection. Ebonization is a dull black coating process on the instrument’s
surface, and instruments may also be surface treated to have a matte ﬁnish
[3,9] (Fig. 4).

Skin hazards are relatively easy to minimize in operating room personnel.

Standard apparel, such as gowns and gloves, provides a barrier to exposure,
as does judicious aiming of the beam. Areas at risk of beam contact may be
shielded with appropriate moistened sponges or drape material [2]. Fire
retardant materials should also be considered. Moist environments, how-
ever, may be in contradiction to safe operation of electrosurgery units [2].
Operating room protocol should never be casual particularly when the laser
is in use. All individuals present need to be appropriately attired with eye
and respiratory protection; laser-warning signs should be in full view on the
doors; and all windows and door need appropriate covers. Before laser acti-
vation, the attending surgeon should announce ‘‘laser on’’ so that no one is
uncertain about beam activation. When not in use, standby modes are appro-
priate to avoid inadvertent lasing [14].

Because most lasers use high-voltage power supplies, the possibility of

electric shock does exist. The likelihood of shock is minimal if operation
is in compliance with instructional manuals. Removal of the exterior hous-
ing for servicing, however, may dramatically increase the risk of serious
injury [5]. Only authorized professional service personnel should ever

540

T.R. Fry / Vet Clin Small Anim 32 (2002) 535–547

attempt to remove the housing to perform maintenance on the laser. Laser
manufacturers are required to build in many safety features to reduce the
chance of shock, electrocution, or inadvertent lasing and to comply with
Food and Drug Administration Manufacturers guidelines. These features
include protective housings, key control, laser door interlocks, shutters or
attenuators, radiation emission indicators, error sensing programs, fail-safe
circuitry and shutter design, power output monitoring, and appropriate

Fig. 3. (A) An example of eye shields used to shield the patient’s cornea during lasing. They are
manufactured in children’s and adult sizes. (B) Corneal shields in place on a feline patient.

541

T.R. Fry / Vet Clin Small Anim 32 (2002) 535–547

classiﬁcation labeling [12]. Other features may include remote control ﬁring,
guarded foot or hand switches to prevent inadvertent lasing, aiming beams,
and emergency oﬀ (kill) switches [6].

Respiratory hazards and plume control

A laser plume (smoke) is often emitted in the course of lasing. This plume

has been shown to contain a wide array of undesirable substances that may
have deleterious eﬀects on both humans and animals. These substances
include viable viral and bacterial particles, mutagenic and carcinogenic par-
ticles, bioaerosols, and dead cellular material. In orthopedics and dentistry,
particulate and metal fumes may be generated [2]. Laser removal of poly-
methylmethacrylate during total joint revision will generate formaldehyde,
carbon monoxide, and hydrocyanic acid [3]. At low levels, all of these sub-
stances can cause irritation of the upper respiratory tract and ocular tissues.
Repeated exposure to laser smoke may lead to chronic conditions including
emphysema, asthma, or potentially cancers in much the same fashion that
cigarette smoke contributes to these chronic conditions [12].

The plume is primarily controlled through the use of smoke evacuators

with appropriate ﬁlters. Routine suction setups, as found in most veterinary
practices, are not suitable. Likewise, neither are simple ventilation systems
because they allow too much plume exposure before the room is eﬀectively
ventilated. Most laser companies do and should provide a smoke evacuator

Fig. 4. An example of instruments with an ebonized surface, which prevents harmful reﬂection
of the laser beam oﬀ the instruments surface onto patient or operator tissues.

542

T.R. Fry / Vet Clin Small Anim 32 (2002) 535–547

as part of the package when a laser is purchased (Fig. 5). If possible, the col-
lection port should be within 2 cm of the lasing site [2]. Smoke evacuation
should start before lasing and should continue for 30 seconds after plume
production [8]. Smoke evacuators require maintenance and routine ﬁlter
changes to be eﬀective. All tubing, connectors, and wands need to be dis-
carded or sterilized after each use because they will contain biologic mate-
rial. A second line of defense against the laser plume is purpose-made laser
facemasks, which will ﬁlter particles down to 0.1 lm (Fig. 6). Standard sur-
gery masks will not stop particles of this size [8]. Because these masks do not
provide an airtight seal, they may not be used in place of a smoke evacuator.

Fig. 5. A smoke evacuator is an essential adjunct to safe lasing to prevent inhalation of the laser
plume.

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These masks are readily available at reasonable prices from many manufac-
turers. As a cautionary note, electrosurgical smoke is identical to that in the
laser plume, but is normally is generated in much smaller volumes [2,14].
Iodine-based preparations should be avoided as preparation solutions
because the lasing of them may generate irritating fumes [14].

Fire hazards and controls

Because of the thermal eﬀects of many lasers, ignition of surgical acces-

sories or even the patient is possible when adequate care is not taken. In the
event of a ﬁre in the operating room, a ﬁre extinguisher should be available.
Drape or sponges need to be moistened when in the immediate operative
ﬁeld. It is important to keep in mind the laser’s wavelength and penetration
characteristics. A CO

laser may be unlikely to penetrate a single layer of

moistened drape material, whereas a Nd:YAG or diode laser may easily
penetrate the same ‘‘safe barrier.’’ Avoid the use of alcohol-based solutions
because of their ﬂammability. Flammable anesthetic agents should ob-
viously never be used in the presence of lasers or electrosurgery. Endotracheal
tubes made of polyvinyl chloride will ignite at 149

F, and red rubber tubes

will ignite at 240

F. Silastic tubes ignite above 700F and are a better choice

when possible laser beam contact with the endotracheal tube is likely [3].
Tubes can be shielded with moistened gauze or with metal tape wrappings.
The most desirable option is to use speciﬁc laser-safe endotracheal tubes
[12,14] (Fig. 7). A second risk for ﬁre with the ignition of endotracheal tubes
is the presence of a near 100% oxygen environment. Injectable anesthetic
protocols should be considered if airway laser surgery is required. Airway

Fig. 6. Laser-speciﬁc facemasks are much more eﬀective at ﬁltering small particles, as contained
in the laser plume, than are standard surgical masks.

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T.R. Fry / Vet Clin Small Anim 32 (2002) 535–547

ﬁres are devastating and life threatening. Although medical management of
this crisis is possible, prevention is the more desirable way to deal with this
problem.

Intestinal gases with a high methane content are prone to ignition in

many species. Possible methods of prevention include evacuation of the
gases using suction and the creation of a barrier by placement of saline-
soaked sponges into the intestinal tract [14,16]. Colorectal ﬁres are possible
if these safety precautions are not followed.

Air embolism has been reported in humans, particularly when laser gases

have been purged into the uterine lumen [8,12]. Although this complication
has not been seen in veterinary medicine, avoidance is desirable.

Administrative issues

Every facility that uses medical lasers needs to appoint a laser safety oﬃ-

cer (LSO), who is primarily responsible for all aspects of that institution’s
laser safety program. In a general practice or private specialty practice, the
LSO duties may be fulﬁlled by either a veterinarian or a technician. In most
academic institutions, individuals from the safety department may fulﬁll
that same role. The LSO is responsible for laser system classiﬁcation (class
I to IV), hazards evaluation, control measures, standard operating proce-
dure development, use of protective equipment, appropriate signage and
labels, and facility modiﬁcation to follow manufacturer’s guidelines on safe
installation [1,2,5]. It is important that the LSO establishes training pro-
grams for all individuals to ensure that all laser users and observers maintain

Fig. 7. Laser-safe endotracheal tubes are much more resistant to perforation and ignition by
the beam than are standard endotracheal tubes.

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T.R. Fry / Vet Clin Small Anim 32 (2002) 535–547

personal safety. Familiarity with established guidelines, local and federal
regulations, advisory standards, and professional recommended practices
are all a requisite part of the LSO armamentarium.

Laser operators need to be familiar with the physics and biologic eﬀects

for the speciﬁc wavelength of laser they are using. This information should
include all components, delivery devices, and instrumentation [2]. Clinical
applications should be gained through self-study, continuing education con-
ferences, and mentoring by experienced laser surgeons. A ‘‘burn and learn’’
philosophy is unacceptable as the means of gaining clinical experience with
the laser [14,16]. When surgeons need to acquire or use a new type of laser, it
is imperative that they be completely retrained regarding all of these areas to
safely use the instrument. In other words, an experienced CO

laser operator

is still a novice when they attempt to use a diode laser. Be strongly cautioned
that clinical experience is not likely to transfer from one laser type to the next.

Perioperative safety programs developed by the LSO should address the

following points according to ANSI: controlled access to the operating
room, eye protection, reﬂection hazards, ﬁre prevention and draping, electri-
cal safety practices, plume evacuation, anesthetic management in airway
and gastrointestinal surgery, and equipment maintenance [2]. The previous
discussion has covered most of these areas in detail. It is reasonable to
assume that if OSHA investigates a veterinary practice for compliance, they
will hold us to the standards outlined by ANSI; the same standards as a
human health care facility.

Summary

Laser safety is a critical component in any laser surgery program. When

used improperly, lasers have the potential to cause severe skin burns, induce
corneal opacity and cataracts, damage the retina leading to blindness, and
cause chronic respiratory diseases. For these reasons, each laser user is obli-
gated to establish and comply with a laser safety program as outlined by
ANSI.

Resources

1. The Laser Institute of America maintains a website [5], publishes the

ANSI 136.1 and ANSI 136.3 documents, and sells a wide array of laser
safety information. Through this resource alone, a veterinarian can set
up a fully compliant laser safety program. Laser Institute of America
13501 Ingenuity Drive Suite 128 Orlando, FL 32826 Phone: 407-380-
1553 www.laserinstitute.org

2. OSHA maintains a website that has links to dozens of other laser safety

sites. www.osha-slc.gov

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3. ANSI meets at intervals to establish guidelines regarding laser use and

safety in both industry and medicine. American National Standards In-
stitute 11 West 42nd Street New York, NY 10036

References

[1] American National Standard for Safe Use of Lasers. (ANSIZ136.1–1996). Orlando (FL):

The Laser Institute of America; 1996.

[2] American National Standard for Safe Use of Lasers in Health Care Facilities. (ANSIZ

136.3–1993) Orlando (FL): The Laser Institute of America; 1993.

[3] Sherk HH, Meller M. Laser safety. In: Sherk HH, editor. Lasers in orthopaedics.

Philadelphia: JB Lippincott; 1990. p. 23–34.

[4] OSHA – Laser Hazards Technical Links. Available at: http://www.osha.slc.gov/SLTC/

laserhazards/index.html. Accessed May 15, 2001.

[5] Laser Institute of America – Laser Safety Information Bulletin. Available at: http://www.

laserinstitute.org/safety_bulletin/lsib/. Accessed May 10, 2001.

[6] Laser Safety Training Tutorial UIUC. Available at: http://www.ehs.edu/

~rad/laser/tutorial.

html. Accessed June 23, 2001.

[7] University of Iowa Health Sciences Laser Safety Program. Advanced Laser Safety Course.

Section 7: Laser Standards. Available at: http://www.vh.org/Providers/TeachingFiles/Laser
Safety/advanced/AdvancedSection7.html. Accessed May 10, 2001.

[8] Laser safety. In: Luxar LX-20 operator’s manual. Bothell (WA): Luxar Corporation; 1996.

p. 2-1–2-27.

[9] Laser safety guide, Marshall W, Sliney D, editors. Orlando (FL): Laser Institute of

America; 2000. p. 1–47.

[10] Bader O, Lui H. Laser safety and the eye. Available at: http://www.dermatology.org/laser/

eyesafety.html. Accessed May 10, 2001.

[11] University of Iowa Health Sciences Laser Safety Program. Advanced laser safety course.

Section 2: biological eﬀects. Available at: http://www.vh.org/Providers/TeachingFiles/
LaserSafety/advanced/AdvancedSection2.html. Accessed May 10, 2001.

[12] University of Iowa Health Sciences Laser Safety Program. Advanced laser safety course.

Section 9: ancillary hazards. Available at: http://www.vh.org/Providers/TeachingFiles/
LaserSafety/advanced/AdvancedSection9.html. Accessed May 10, 2001.

[13] Laser hazards–University of Waterloo safety oﬃce. Available at: http://www.adm.

uwaterloo/infohs/lasermanual/documents/section6.html. Accessed May 10, 2001.

[14] Bartels KE. Laser surgery. In: Bojrab MJ, editor. Electrosurgery and laser surgery, 4th

edition. (Current Techniques in Small Animal Surgery). Baltimore (MD): Williams and
Wilkins; 1998. p. 45–52.

[15] University of Iowa Health Sciences Laser Safety Program. Advanced laser safety course.

Section 11: the controlled area. Available at: http://www.vh.org/Providers/TeachingFiles/
LaserSafety/advanced/AdvancedSection11.html. Accessed May 10, 2001.

[16] Fry TR, Bartels KE. Laser surgery. In: Harari J, editor. Small animal surgery secrets.

Philadelphia: Hanley and Belfus; 2000. p. 54–7.

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The economics of surgical laser technology

in veterinary practice

James R. Irwin, DVM

Sulphur Springs Veterinary Clinic, St. Louis, MO 63021, USA

Philosophy of the changing marketplace

Changing marketplace

Veterinary medicine is a dynamic, continuously evolving enterprise. Ignor-

ing this fact can be the ﬁrst step toward failure. Veterinarians must adopt a
proactive attitude to stay successful. What worked in past years may not
work as well today and may not work at all in the future. Clients are be-
coming more educated and, therefore, expect more from their veterinarians.
Internet exposure may be mainly responsible for this changing expecta-
tion; however, regardless of the source of client’s increased expectations,
veterinarians must be willing to respond. They must continually analyze
their client’s needs and change to meet these needs to ensure their success
(Fig. 1).

Technology explosion

Veterinarians are literally in a sea of new technology. It is a mistake to

not take advantage of these new technologies. To survive and grow, veter-
inarians must embrace change. They must be willing to continually explore
new and better technology to provide new and better health care service to
their clients. Most successful practices have a posted mission statement that
proclaims that they are progressive and desirous of providing state-of-the-
art care. Laser technology easily ﬁts into such a progressive practice. When
the advantages of laser technique (i.e., less hemorrhage, less pain, less after-
care, and faster recovery) are examined, it becomes an obvious ﬁt.

Vet Clin Small Anim 32 (2002) 549–567

E-mail address: jirwin7279@aol.com (J.R. Irwin).

0195-5616/02/$ - see front matter

PII: S 0 1 9 5 - 5 6 1 6 ( 0 2 ) 0 0 0 0 5 - 0

Making surgery proﬁtable

Surgery should not be overlooked as a proﬁt center

With or without adding laser technology, the inpatient care and surgical

portion of the hospital should be able to produce signiﬁcantly more income
than most practicing veterinarians generally realize. Unfortunately, many
practitioners have viewed this area of their practices as a nonproﬁt necessity.
This negative connotation about inpatient care and surgery may have
evolved from improper fee schedules and the resulting lack of suﬃcient
income for providing these services. Reluctance to charge adequate fees has
also resulted in clients developing an under appreciation for the value of the
veterinarian’s surgical skill. ‘‘If you undervalue what you do the world will
undervalue who you are’’ [1]. Income-producing areas of the practice that

Fig. 1. Laser surgery in veterinary medicine is growing tremendously. The economic impact is
just being realized.

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J.R. Irwin / Vet Clin Small Anim 32 (2002) 549–567

should be developed are in the service sector rather than the inventory sector
of the veterinary business. Relying heavily on vaccinations and over-the-
counter products for practice income may soon become a strategic error.
Price competition is heightened when the consumer cannot distinguish a dif-
ference between a service, such as vaccinations, being oﬀered from a com-
peting practice [2]. With their inherent requirement of high technical
knowledge and skill, inpatient care and surgery are not as vulnerable. When
all else fails, the ability to interpret diagnostics and perform surgery will
surely remain solid.

Identify and assign value to all the ingredients to providing surgical care

By carefully examining all the activities related to a surgical procedure, it

becomes obvious that there is signiﬁcant income-producing potential; yet
many items may easily be overlooked. By assessing the value of these and
other services it is possible to transform the surgical wing into a legitimate
proﬁt center. For the most part, these inpatient care services are relatively
not price sensitive and are not readily available anywhere, except at a full-
service veterinary facility. They also promote better patient care and are
generally accepted without question by clients. Consider the following list
of income-producers related to surgery:

• Laboratory, radiology, ultrasound, cytology, and other diagnostic fees

involved in getting the patient into surgery

• Operating-room fees for the usage and maintenance of the operating

room and routine equipment, medical waste disposal, surgical pack
preparation, and cleanup

• Special-instrument fees for the use of high-technology instruments,

such as a surgical laser, endoscope, or videoscope

• Support staff fees for technical assistance, surgical preparation, record

keeping, logging narcotics, and ordering supplies

• Patient care fees for the costs of ﬂuid therapy, intravenous catheter

maintenance and replacement, ﬂuid pumps, oxygen, incubators, warm-
ing pads, pain management, intensive care, nursing care, dressing
changes, antibiotics, and other supportive medications

• Anesthesia fees for the costs of the drugs, intubation, administration

and maintenance of the anesthesia, the use of anesthetic monitors,
and administration of anesthetic reversal agents

• Surgeon’s fees for the expertise, experience, and techniques involved in

the actual procedure

• Followup fees for histopathology, cytology, culture, and radiographs

Enhancing the surgical wing by adding laser technology

After identifying the surgical wing as a viable proﬁt center, attention

should then be directed toward enhancing the technology of the surgery area

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with the goal of providing an even higher level of care. A progressive practi-
tioner should next consider adding a surgical laser, because it can greatly
increase the surgical capabilities of the practice.

Laser technology does not require a specialist to use it. The learning curve

for most practitioner-surgeons can be very short. Procedures that have been
performed using a scalpel or electrosurgery can usually be performed with a
laser. Some procedures are so much better with a laser that a new standard
may be created. Elongated soft palate resection can become a simple proce-
dure, well within the range of most practitioners. Some procedures, such as
laser ablation of skin tumors, more precise tumor excision, feline onychect-
omy, lick granuloma removal, stomatitis treatment, and many others, are
greatly enhanced by using laser technology.

Purchasing decision

Exploring your professional needs

Laser technology is only sensible if the individual has reasonable surgical

skills. Simply acquiring a surgical laser will not make a person a good sur-
geon. Furthermore, a person investing into a new technology, such as laser,
must be innovative and willing to accept the fact that very little has been
written about the use of lasers. In fact, this text may be the ﬁrst that is dedi-
cated to the use of lasers in veterinary medicine. There have been laser sur-
gery wet labs at national veterinary conferences and regional American
Animal Hospital Association meetings, as well as numerous all-day laser
workshops sponsored by manufacturers. Otherwise, most procedural tech-
niques have evolved from current laser users with information spread by word
of mouth, Internet, and newsletters. Information dissemination through
objective evaluation and peer-reviewed articles needs to improve and should
improve in the future.

Return on investment—consider a cost-to-production analysis

It is the author’s opinion that the decision of whether to purchase a piece

of equipment should be based more on the purchaser’s ability to generate
cash ﬂow by use of the equipment. It is a simple cost-production relation-
ship of comparing cash in to cash out. For example, if a piece of equipment
can produce $1000 net income per month and the loan or lease payment is
only $500 per month, it becomes a good investment. It is important to factor
in all expenses, including expendable supplies and routine maintenance.

Compare investing in a laser to other equipment

Looking around the clinic, it may become interesting to compare the cost–

production relationship of other pieces of equipment that are of compara-
ble investment costs. Consider the computer system, radiograph machine

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with ﬁlm processor, diagnostic ultrasound, and an in-house laboratory. Each
item has a rationale for its existence in a practice; however, the cost–produc-
tion relationships may vary greatly. Factors such as maintenance costs, supply
costs, associated labor costs, and usage volume will inﬂuence the cost–produc-
tion comparison. Other factors, such as individual interests, experience, equip-
ment longevity, and improvement in patient care, should also be considered.
The following examples are general observations taken from the author’s
practice.

A new computer system with all the associated hardware and software

has an investment cost similar to laser equipment. Computer systems have
a high maintenance cost and a high supply cost. Although computer systems
certainly do not generate income directly or improve patient care, they
greatly increase eﬃciency, which ultimately reduces labor costs. Therefore,
its cost–production ratio is high.

A radiograph machine with a ﬁlm processor also has a high initial invest-

ment cost similar to laser equipment. The radiographic equipment (proces-
sor) has high maintenance cost, high supply cost, and a high labor cost
associated with its usage. Furthermore, the use of radiographic equipment
varies greatly from time to time in most practices, causing it to often yield
a poor cost–production comparison. It would be diﬃcult to imagine practic-
ing quality medicine, however, without radiographic capabilities in a general
veterinary practice.

An ultrasound machine has a low maintenance cost and even has low

supply costs. With its associated high learning curve, however, it is often
subject to underuse, thereby aﬀording it a poor cost–production comparison
for many practices.

An in-house laboratory has a high initial investment cost, a high mainte-

nance cost, a high supply cost, and is somewhat labor intensive. It greatly
enhances patient care, however, and its use is generally so high as to provide
a very good cost–production comparison.

It is also important that the entire practice team enthusiastically supports

the purchase of the equipment and demonstrates interest in marketing its
use. Without such support, the volume of use will not be adequate to make
it a good investment. The role of support staﬀ in marketing the laser will be
discussed later in this article.

Typical laser use scenario demonstrates proﬁtability

If a laser instrument costs approximately $35,000 and supplies, mainte-

nance, and lease expense for the equipment costs $10,000, the total cost is
$45,000. If the equipment is leased for ﬁve years, the cost per year is
approximately $9000. Dividing that number by 52 weeks per year yields a
total weekly expense of $173. If the doctor charges $60 per usage, then
2.88 procedures are required each week. Therefore, after reaching 2.88 pro-
cedures per week, any amount gained is proﬁt. If a clinic with one doctor

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performs eight laser procedures per week, the clinic realizes a proﬁt on ﬁve
procedures. Five procedures at an average charge of $60 for each procedure
becomes $300 proﬁt per week.

Not all lasers are alike—know what you are buying

Finding a laser that is right for you

Other articles in this issue have discussed laser physics, how diﬀerent

wavelengths of laser light are created, and how these diﬀerent wavelengths
aﬀect target tissues. Although there are numerous laser wavelength applica-
tions in medicine, especially for humans, it is the author’s opinion that, at
this time, only two types of lasers are worthy of consideration by the veter-
inary surgeon: carbon dioxide (CO

) laser with a wavelength of 10,600 nm

and diode lasers with wavelengths between 810 and 980 nm. CO

and diode

lasers each have their advantages and disadvantages, and their uses are
somewhat varied. This article will not discuss all of the technical diﬀerences
between CO

and diode lasers. It is important, however, for the prospective

user to be aware of the diﬀerences and to make the proper selection based on
his or her intended use of laser technology. It is entirely feasible that veter-
inarians may someday use both types of lasers in routine practice or even a
third type of laser; however, at this time, it is more likely that the prospective
veterinarian will only be acquiring one speciﬁc type of laser.

It is the author’s opinion that the CO

laser oﬀers the most advantages

for general soft tissue surgery. This opinion was formed after using both the
CO

and diode lasers for routine small animal procedures. Although the

laser was more expensive, it provided cleaner incisions, was easier to

handle, was safer to operate, and was less likely to cause thermal damage
to deeper tissues than the diode laser. In addition to having a lower cost, the
diode laser’s main advantage was its ability to pass through an endoscope.

Comparison of various features by diﬀerent vendors

After considering the positive and negative characteristics of CO

and

diode lasers, the purchasing decision should now focus on a comparison
of features oﬀered by opposing vendors. Each vender oﬀers a machine that
has diﬀerent features, which should be studied before purchase. Price alone
should not be a deciding factor because there are other important considera-
tions, such as:

• Safety features
• Portability
• Durability
• Maintenance
• Availability of supplies, such as waveguide tips, ﬁbers, and smoke evac-

uation ﬁlter components for smoke evacuators

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• Expected life span and cost of recharging the lasing medium
• Reputation of the vendor
• Availability of technical and educational support

Comparison of new and used equipment

At this point, the decision may be whether to purchase a new or used unit.

Again, price alone should not be the deciding factor. Although a used unit
may require a lower initial investment, the issues that should be considered
before purchasing a used piece of high-technology equipment include:

• Reliability of the machine
• Required maintenance contracts to keep the device in working order
• Guarantees or warranties
• Reputation of the manufacturer
• Reputation of sales organization
• Availability of replacement parts
• Application to veterinary medicine (outdated technology from laser

units obtained from human hospitals versus used veterinary units)

• Ease of use (units with articulating arms versus ﬁber or waveguide tech-

nology)

Acquiring a laser—leasing versus purchasing

Purchasing

There are many arguments both for and against leasing or outright pur-

chasing a laser unit. Although several veterinary economists have expressed
their opinion [3,4], it ultimately becomes a personal preference, and the
veterinarian should involve his or her accountant in the ﬁnal decision.

If the prospective purchaser has adequate cash reserves, a direct purchase

will be less costly. There are some considerations, however. Although an
outright purchase will result in a lower cost, investing hard cash may deplete
emergency reserves and may decrease future investment opportunities.
Funds taken from cash reserves can no longer earn interest income. A bank
loan can also be used to purchase a laser. In most cases, however, a signiﬁ-
cant down payment is required. A bank loan oﬃcer may require a deposit of
15% to 20% of the purchase price.

Leasing

A lease arrangement is generally more suitable for the veterinarian who

has limited investment funds. If the purchaser uses a vendor-sponsored leas-
ing company, the ultimate costs will likely be higher; however, the veterinar-
ian can beneﬁt from the ease of acquisition and the beneﬁt of not tying up

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ﬁnancial reserves. With many leasing companies requiring only the ﬁrst pay-
ment up front, the leased machine is practically 100% ﬁnanced. A leased
machine is an oﬀ-balance sheet ﬁnanced item, which means it will not show
up on loan information. With the speed and ease of leasing, a practitioner is
likely able to begin using the machine immediately and to realize proﬁts
sooner. Some leases have diﬀerent end-of-lease buyout terms and diﬀerent
tax considerations that should be considered.

Types of lease

Traditional capital leases are the most popular. This type of lease has a

10% buyout at the termination of the lease period. These lease payments are
100% deductible. The buyout is optional, which means that if the technology
becomes outdated at the lease termination the machine can be returned. The
practitioner can then write a new lease for an instrument with newer tech-
nology.

Another type of lease is the $1 buyout lease. In this situation, the veter-

inarian will generally be signing a lease with higher scheduled payments;
however, the ﬁnal buyout price is only $1. For tax purposes, the Internal
Revenue Service (IRS) considers this type of lease as an actual cash purchase
at the onset of the lease. The IRS also allows for a Section 179 deduction the
ﬁrst year ($24,000 maximum at time of this writing). The equipment is de-
preciated over the IRS statutory depreciation life. Because the total out-
of-pocket expense is generally lower, this lease option is preferable for the
practitioner who knows at the onset that he or she wants to buy the
instrument.

Another type of lease is the fair-market-value lease. With this lease, the

practitioner acquires a short-term lease with lower scheduled payments;
however, the IRS does not allow the Section 179 deduction. It does allow
for deductions of lease payments. At the end of the lease, the leasing com-
pany will establish a buyout price, which is likely to be signiﬁcantly higher
than the previous examples. This type of lease is a good option if the practi-
tioner knows at the onset that he or she does not want to purchase the
equipment at the end of the lease [4].

Marketing programs for laser procedures

Marketing program must be created and ready to use

As stated earlier, a marketing program should be created and ready to be

used on the ﬁrst day after purchase. Support staﬀ must be enlisted, trained,
and ready to help in the marketing of laser technology, because the ultimate
success is directly related to having a practice team working in unison.
Unfortunately, veterinarians are not usually experienced in or have training
in marketing. Most veterinary practices are usually small businesses without
a marketing department. Often, practices are so small that they do not even
employ a full-time business oﬃce manager. As a result, many veterinarians

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often ﬁnd themselves in a situation of tackling marketing without any train-
ing or trained personnel to guide them. Without a good marketing plan,
which includes establishing suitable fees, an expensive piece of equipment,
such as a laser, may fail to provide adequate income.

It is important to consider how busy practitioners have historically

approached marketing. Allegedly, veterinarians simply slap a fee on a new
service or product without a thorough understanding of the true costs asso-
ciated with it. Unfortunately, the fee is either too low to generate income or
too high to generate sales. In either instance, the necessary income is not
generated, and, ultimately, the service or product falls into disfavor.

Worse yet, the veterinarian becomes remorseful at the moment of the sale

to the client and reduces what would have been an appropriate fee or alters
some other fee for an associated service to compensate. By their caring na-
ture, veterinarians are uniformly guilty of feeling over-responsible. All too
often they feel the need to reduce a fee for client acceptance; sometimes
before a client has even had a chance to voice disapproval.

Creating a marketing strategy: recognizing and utilizing the unique
qualities of a CO

laser (or another speciﬁed surgical laser,

taking into account its inherent advantages)

Successful marketing of any product or service involves recognizing and

utilizing its inherent unique qualities. Once identiﬁed, all that remains is to
create a program that utilizes these qualities in a desirable fashion, devise an
appropriate pricing formula, and establish a means of educating the con-
sumer. A CO

laser oﬀers several valuable and unique qualities that are most

amenable to the pet-owning public. Table 1 provides a quick review of the
unique qualities and their corresponding marketing ‘‘hot button’’ for CO

laser technology.

By focusing on these features, practitioners should be able to create some

speciﬁc applications that will ultimately be pleasing to the client, promote
better health care to the pet, and provide good income.

Recognizing the needs of today’s clients

Client interests are gradually changing. Any seasoned practitioner can

well attest to this fact. Programs that were successful ﬁve years ago may not

Table 1
Unique qualities and corresponding marketing ‘‘hot button’’

Unique quality

Marketing ‘‘hot button’’

Seals blood vessels

Better control of hemorrhage

Seals lymphatic vessels

Less swelling

Seals nerve endings

Less pain

Clean, precise dissection

More accuracy

Kills bacteria in the operative ﬁeld

Can be used for contaminated wounds

Kills tumor cells in the operative ﬁeld

Less seeding with exfoliated tumor cells

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be successful today. Furthermore, what is successful today will likely not be
successful ﬁve years from now. In the author’s practice, it has been observed
that clients are most readily drawn to any product of service that provides
instant gratiﬁcation, convenience, and is ‘‘pain free’’ for their pet. The
unique qualities of laser surgery satisfy all three of these needs. For example,
laser declawing of cats provides a much faster recovery, requires minimal or
no bandaging, and is much less painful.

Consider doing more outpatient procedures

The mere fact that laser surgery causes less bleeding, which in turn

reduces aftercare, creates a possibility of providing more outpatient surgery.
Many clients appreciate being able to take their pets home as soon as pos-
sible after surgery, and they especially prefer not having to leave them over-
night. In fact, the requirement for keeping the pet overnight is a very
common barrier to accepting a surgical recommendation. Yet, because of
habit and fear of postoperative complications, practitioners have been slow
to accommodate clients in this regard. With laser surgery, however, pets can
often be released sooner with less concern for aftercare problems. Increasing
emphasis on outpatient procedures will likely increase surgery volume and
satisﬁes many diﬃcult clients.

Marketing laser procedures to the public and maintaining professionalism

It is important to focus on the positive features of laser surgery yet not

overstate them. The laser is a high-tech tool, not a futuristic toy. Clients
being primed for ‘‘the laser’’ by observations of procedures on the human
side of medicine may have high expectations. These expectations may be
based on very talented surgeons using very sophisticated equipment in very
controlled settings. Caution should be used by the new laser surgeon in mak-
ing claims for cures or in guaranteeing results.

Internal marketing of services

Veterinarians need help in educating clients about the services and prod-

ucts that they have to oﬀer. Most industries have full-time marketing
departments with well-polished marketing plans to educate their customers.
Veterinarians, however, have much less structure to their approach. The ﬁrst
goal is simply to make the client aware that the clinic has invested in laser
equipment. Awareness will likely translate into interest. Within a practice,
there are many possibilities for low cost marketing.

• Consider hospital tours. Most clients have little knowledge of the mag-

nitude of veterinarian’s equipment investment and the activities that
occur in the back rooms of veterinary clinics.

• Client newsletters can spread the word.

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J.R. Irwin / Vet Clin Small Anim 32 (2002) 549–567

• Examination room posters, buttons, videos, and pictures will help edu-

cate clients.

• Computer invoice notes, departure notes, and reminder footnotes will

also help.

• Support staff testimonials about their observations, perhaps on their

own pets, are very effective.

External marketing of services—mass media endeavors

A larger number of potential clients can be reached with outside market-

ing activities. Care should always be used to maintain professionalism while
marketing. With media exposure, be certain to follow traditional rules for
aseptic technique. When doing a laser procedure for photographic purposes,
be certain to wear surgical gloves, be attired appropriately with laser safety
mask, laser-safe eyewear, and use a smoke evacuator. These obvious safety
rules should always be followed, but sometimes tend to be overlooked at crit-
ical times, such as when the photographer is pointing a camera at you!

• Newspaper articles or press releases announcing new services generate

much public attention.

• Web sites are becoming commonplace. Many laser users have listed

useful information concerning their laser procedures on web sites. Join-
ing a laser-user organization can help veterinarians attract new clients
by listing the veterinarian’s services on the Internet. Clients can easily
search hosted web sites for veterinarians who use lasers. (Veterinary
Surgical Laser Society, Ltd., 19621 Fisher Ave., Poolesville, MD
20837, www.
vetsls.com; American Society for Laser Medicine and Surgery, 2404
Stewart Square, Wausau, WI 54401, www.aslms.org.)

• Yellow page advertisements are another source of advertising. Veteri-

narians can provide information for clients within their telephone list-
ing advertisement.

• In areas where the veterinarian is the only one equipped with a laser or

perhaps is the only one performing a speciﬁc procedure, referrals from
colleagues are common. Examples include laser declawing, soft palate
resection, and complex tumor excision. If the prospective veterinarian
has developed special skills, he or she may choose to notify neighboring
veterinarians.

Creating marketing categories

Marketing the laser to clients requires separating procedures into cate-

gories for more eﬀective marketing. Support staﬀ can assume the entire role
of marketing all the common elective procedures (category 1). Pending the
doctor’s approval, the support staﬀ can also assume a major portion of
marketing laser use in all the nonelective procedures (category 2). For all

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laser-speciﬁc procedures (category 3), the doctor simply advises the client on
his or her choice to use laser technique.

For all categories, the laser fee charged is in addition to the regularly

charged surgical fees. Make a client ‘‘hype sheet’’ available to help the sup-
port staﬀ explain the advantages of laser surgery.

Category 1: Common elective procedures

Oﬀered as an option for routine elective procedures at front desk by sup-

port staﬀ. Examples include ovariohysterectomy, castration, declaw, and ear
crop.

Category 2: Nonelective procedures

Oﬀered as an option for many nonelective surgical procedures by doctor

or support staﬀ member where it is not essential, yet improves the proce-
dure. Examples include tumor removals, ear canal ablation, and facial fold
reduction.

Category 3: Laser-speciﬁc procedures

These are procedures where the advantages of using laser technique out-

weigh the conventional scalpel surgery technique. Clients are made aware of
the veterinarian’s choice to use laser surgery. Examples include soft palate
resection, feline onychectomy, or vascular tumor excision.

Laser-optional procedures may eventually be recategorized as laser-

speciﬁc procedures as they gain acceptance with clients. In other words, if the
doctor notices high owner compliance in accepting the laser option for a
particular procedure, the procedure may be reclassiﬁed as laser speciﬁc. This
approach is commonly the case with laser feline onychectomy. Client accep-
tance of laser declawing will quickly escalate in most practices, thereby mak-
ing it a good candidate to become a required rather than optional technique.
This style of gradual development allows the practitioner time to acquire
conﬁdence in marketing laser procedures.

Twelve-month study in author’s practice

In the ﬁrst twelve months of using a CO

laser in the author’s practice,

the following statistics were compiled showing the percent compliance on
accepting laser surgical technique where applicable. The study included sur-
gical procedures that were amenable to conventional ‘‘cold steel’’ surgery.
Fees were charged in addition to the normal fees that would have been
charged without using laser technique. All fees were itemized on the invoice
as an individual entity. No fees were reduced from the standard fee schedule.
Therefore, these fees represent the true additional income generated by
oﬀering laser surgery (categories 1 and 2) and simply requiring the laser
be used for the procedure (category 3) (Table 2).

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J.R. Irwin / Vet Clin Small Anim 32 (2002) 549–567

Marketing is support-staﬀ driven

The support staﬀ readily supports and recommends the laser surgical

option for many routine procedures. They carry major credibility in a veter-
inary practice, because clients will often confer with them after the doctor
leaves the examination room. After having seen several remarkable laser
surgery procedures and the animals’ quick recovery, the support staﬀ soon
became true disciples of laser surgery. After checking with the doctor, the
support staﬀ routinely mentions the laser surgery option to clients schedul-
ing elective procedures. They show pride in their clinic and enjoy seeing the
animals respond so favorably to surgery.

The support staﬀ should not, however, market procedures the veterinar-

ian has deemed as being laser-speciﬁc procedures. The veterinarian makes
the decision in these cases, so that there is no option given to the client. The
doctor simply elects to perform the intended procedure with laser. Routine
elective procedures, especially wellness care procedures, such as ovariohys-
terectomy, declawing, ear cropping and others, are all well within the ethical
range of support staﬀ recommendation.

Spend more time educating the client

An educated client is more likely to become a compliant client. Oﬀering

new technology, such as laser surgery, to provide an improved level of ser-
vice usually results in a higher fee. Because of the higher fees associated with
laser surgery, clients are less likely to show interest in a procedure unless, of
course, they understand the reason for the increased fee. A client cannot
accept a concept or procedure he or she does not understand. Acceptance
of a higher fee simply requires a higher level of client education. All too
often veterinarians take this role too lightly. Without fully understanding
the advantages of a new service or product, a client is not going to express
interest in paying the higher fee. Laser surgery technique has many advan-
tages over conventional cold steel technique, especially in soft tissue surgical
procedures. Yet the client must be informed of these advantages.

Technology is advancing exponentially and with it comes the need for

more and more client education. Veterinarians are usually unable to devote
the time and energy for one-on-one marketing with the client. Instead, they
should consider using their time more productively, studying laboratory
reports, performing procedures, or even reading journals. Support staﬀ will

Table 2
Twelve-month study at Sulphur Springs Veterinary Clinic, St. Louis, MO

Procedure category

No. accepting option (%)

Fees generated

198 category 1 procedures

92 (46%)

$6070

222 category 2 procedures

120 (54%)

$11,280

164 category 3 procedures

N/A (required)

$19,460

644 total procedures

$36,810

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J.R. Irwin / Vet Clin Small Anim 32 (2002) 549–567

need to ﬁll the marketing role; however, they in turn must be educated.
Therefore, client education begins with good staﬀ education. Many progres-
sive clinics conduct weekly staﬀ educational meetings to discuss new high
technology products and services. As staﬀ members become more educated,
they become more productive, more enthusiastic about their job, and more
supportive of their clinic.

Pillars for sound marketing of veterinary laser services

Oﬀer the best care available

Practitioners should oﬀer the best available care to the client. Modern

technology has brought to the veterinary profession many new products and
services. Veterinarians are often aware of newer and better treatments, yet
shy away from oﬀering them. Failing to oﬀer the proper service may in fact
be a form of ‘‘supervised neglect.’’ Veterinarians commonly make the mistake
of understating a problem, perhaps to please the client, forgetting that it is
better to tell the clients what they need to hear rather than to tell them what
want to hear! An example of this phenomenon is illustrated in the following
scenario: after examining an animal presenting with a lump, the veterinarian,
wanting to please the client, states ‘‘Oh, that’s probably a lipoma, just watch
it.’’ Yet had he or she oﬀered cytology or biopsy or even removal it may have
been found that this ‘‘lipoma’’ was actually a mast cell tumor!

Do not prejudge the client

Do not prejudge the client’s interest in paying for a service or product.

Veterinarians commonly make a poor assessment of the client’s interest, and
then mistakenly assume that a client would be unwilling to select a particu-
lar procedure. In fact, judgments are often made without any client input.
The emphasis here is to oﬀer laser technique for routine, elective procedures
rather than limiting it to procedures that are more complex. Some proce-
dures, such as elongated soft palate resection, are less controversial, because
results are much better with laser surgical technique and therefore are not
oﬀered on an optional basis. Although the newly initiated laser surgeon is
aware of the improved results obtained using the laser for more routine pro-
cedures, he or she is still not comfortable recommending them to the client.
Perhaps their reluctance is caused by the fear of client refusal. By having a
trained staﬀ member, however, simply oﬀering laser surgery as a choice to
clients and noting their interest and enthusiasm, a doctor will quickly realize
his or her misconception.

Avoid subsidizing the fee

Undercharging for laser procedures can be disastrous, because laser

equipment is indeed expensive! When creating an invoice for services,
guilt-ridden veterinarians will commonly drop one fee to compensate for

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J.R. Irwin / Vet Clin Small Anim 32 (2002) 549–567

another. Creating high fees for a laser procedure and then shying away at
the last moment will certainly ruin proﬁtability. This tendency is especially
common in multidoctor practices. Adhering to a structured marketing plan
combined with excellent client education, such as the one described will help
prevent this.

Invoicing laser procedures

Developing an invoice system

First, create a chart listing all the surgical procedures in which laser tech-

nique may be applicable. Post this chart in the surgery area, invoicing area,
and the outpatient estimate area. Assign all the commonly performed pro-
cedures by the procedural diﬃculty, ‘‘laser-on’’ time, and laser tip or ﬁber
wear to a corresponding laser option level number. A workable number
of levels is ﬁve (Table 3). Therefore, all laser surgical procedures would fall
into one of these ﬁve levels. The only computer codes needed would be the
creation of ﬁve service codes; one for each of the laser option levels. Fees
should be structured in the computer at increasing amounts for each level.
The lowest fee would be laser option level 1, and each increasing level would
have a proportionately higher fee.

When the invoice is created, the fees for a particular procedure would be

the standard fees normally applied before laser use. Thus the laser option fee
becomes simply an additional fee. By having add-on fees at various levels,
staﬀ will be less likely to omit or reduce the additional fee required for using
the laser. Because laser equipment is expensive, an adequate fee structure
must be implemented and followed!

This technique has several advantages: (1) it requires the creation of only

ﬁve or six computer codes; (2) it becomes very easy to modify these codes if
you decide to change prices; (3) it prevents that last-minute ‘‘guilt trip’’ fee
trimming that happens so often, especially in multi-doctor practices; and (4) it
makes it easy to track laser income.

Next, a decision must be made as to how detailed the client invoice

should read. This step is simply a personal preference. Many practices prefer
a simple one-line fee, whereas others prefer a more detailed approach to the
invoice demonstrating an itemized list of all the components. The goal is to
charge a fee that appropriately represents the use of the equipment (invest-
ment, maintenance, and licensing fees), disposable supplies (tips, ﬁbers,
masks, and ﬁlters), technician’s time (assistance, record keeping, cleaning),
and the surgeon’s technical skill and expertise.

Three approaches to invoice presentation

Simple invoice system

Laser option levels each reﬂect a ‘‘total fee’’ for the laser portion of the

service. Each fee is created by factoring in all the costs associated with that

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J.R. Irwin / Vet Clin Small Anim 32 (2002) 549–567

ble

Samp

chart

sted

auth

or’s

clin

Laser

surgery

additional

fees

Level

Skin

tumors

Papilloma

ablation

1–3

Papilloma

ablation

4–6

Papilloma

ablation

7þ

——

—

Papilloma

excision

1–3

Papilloma

excision

4–6

Papilloma

excision

7þ

—

Melanoma

ablation

elanoma

ablation

—

Melanoma

excision

small

Melanoma

excision

medium

Melanoma

excision

large

—

Sebaceous

cyst

excision

small

Sebaceous

cyst

excision

medium

Sebaceous

cyst

excision

large

——

—

ast

cell

tumor

small

Mast

cell

tumor

large

—

Perianal

and

gland

tumor

—

nal

sac

tumor

—

Invasive

skin

tumor

small

Invasive

skin

tumor

medium

Invasive

skin

tumor

large

Miscellaneous

skin

tumor

small

Miscellaneous

skin

tumor

medium

Miscellaneous

skin

tumor

large

——

Subcutaneous

tumors

Lipoma

small

Lipoma

edium

Lipoma

large

—

Spindle

cell

tumors

small

Spindle

cell

tumors

medium

Spindle

cell

tumors

large

—

Lymphatic

tumor

small

Lymphatic

tumor

medium

Lymphatic

tumor

large

—

Carcinoma

small

Carcinoma

edium

Carcinoma

large

Oral

surgery

Epulis

small

Epulis

large

—

elanoma

excision

small

Melanoma

excision

large

—

Invasive

tumor

small

Invasive

tumor

medium

Invasive

tumor

large

—

Feline

stomatitis

ablation

small

Feline

stomatitis

ablation

large

—

Eosinophilic

granuloma

—

Soft

palate

resection

small

Soft

palate

resection

medium

Soft

palate

resection

large

Eye,

eyelid

surgery

Lid

tumor

ablation

small

Lid

tumor

ablation

medium

Lid

tumor

excision

medium

Lid

tumor

excision

large

—

Stye

ablation

—

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J.R. Irwin / Vet Clin Small Anim 32 (2002) 549–567

Corneal

ulcer

ablation

————

Distichiasis

small

Distichiasis

medium

Distichiasis

large

—

land

third

eyelid

Enucleation

—

Entropion

‘‘XXX’’

Entropion

incision

small

Entropion

incision

medium

Entropion

incision

large

—

Ear

canal

Pinna

surface

ablation

small

Pinna

surface

ablation

medium

Pinna

surface

ablation

large

——

—

Ear

canal

tumor

small

Ear

canal

tumor

large

—

Ear

canal

ablation

(each)

—

Ear

canal

lateral

section

—

Ear

crop

small

Ear

crop

large

—

Skin

procedures

—

Lick

granuloma

ablation

small

Lick

granuloma

ablation

large

—

bscess

surgery

small

Abscess

surgery

large

—

Skin

fold

ablation

small

Skin

fold

ablation

medium

Skin

fold

ablation

large

—

Pad

corns

Nasal

keratosis

—

General

surgery

assist

OVH

cat

OVH

Dog

—

Neuter

cat

Neuter

dog

—

Declaw

front

only

Declaw

All

—

Dewclaw

dog

(both)

————

—

bdominal

incision

—

Intraabdominal

procedure

—

Thoracic

incision

Intrathoracic

procedure

—

igit

amputation

small

Digit

amputation

medium

Digit

amputation

large

—

Perineal

urethrostomy

—

Skin

surface

ablation

small

Skin

surface

ablation

medium

Skin

surface

ablation

large

—

are

assig

each

level.

The

level

determ

ined

the

diﬃcult

the

proce

dure

and

the

amo

unt

time

laser

equipm

ent

used.

Fees

charged

are

additio

the

regular

surg

ery

fees

that

ould

have

norm

ally

charge

the

proced

ure

had

perform

conven

tional

(no

nlaser)

tech

nique.

having

only

ﬁve

leve

ls,

compu

ter

with

app

ropriate

fee

can

easi

assig

ned

each

level.

the

fees

anged,

only

the

ﬁve

compu

ter

fees

juste

Abbre

viatio

OVH

ovario

hys

terectomy.

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J.R. Irwin / Vet Clin Small Anim 32 (2002) 549–567

procedure. The fee is the total cumulative fee of all the laser-related costs
plus the surgeon’s fee. The client invoice simply lists one line for the corre-
sponding laser option level. Otherwise, the invoice contains all the other
routinely itemized fees, such as anesthesia and hospitalization. With only
ﬁve code numbers, this system requires the least eﬀort in computer code
creation. It is the simplest system to alter when fees are periodically
adjusted. It also is the easiest to track laser productivity (Table 4).

Group service code invoice system

The system uses the same laser option level classiﬁcation chart; however,

the invoice reﬂects more information. The exact method by which this sys-
tem is created is dependent on which computer software system is used by
the practice. Many computer systems allow for the creation of group ser-
vices or code kits. Entering only one code number automatically lists all the
items previously grouped or formatted into that code number. It is added
directly to the invoice with the other service codes for the procedures.

Group service invoice might list the following items on the invoice under

each of the laser option levels listed above. Laser options I, II, III, IV, and V
would list the same four fee items at correspondingly higher fees.

• Laser procedure fee
• Laser tip or ﬁber fee
• Laser assistant’s fee
• Laser disposable items

Complex invoice method

This method also uses the same laser option level classiﬁcation chart. In

this method, however, the invoice reﬂects even more information. Each item
is identiﬁed with a computer code. A checkoﬀ sheet is used by the surgeon.
This system is especially useful in larger multidoctor practices (Fig. 2).

Summary

A decision to invest in and develop laser technology should only be made

after a thorough investigation and comparison of the available types, ven-
dors, available features, and purchasing options. A sound marketing pro-
gram must then be used for introducing laser technology to the staﬀ,
clients, and colleagues. Without adhering to such a program, a practice will

Table 4
Example of simple invoice system

Computer code

Laser option level

Sample fee

Laser option level 1

$60

Laser option level 2

$90

Laser option level 3

$120

Laser option level 4

$150

Laser option level 5

$180

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J.R. Irwin / Vet Clin Small Anim 32 (2002) 549–567

not experience the necessary proﬁtability following the purchase of a laser.
Staﬀ enthusiasm and support will dwindle, and ultimately the laser invest-
ment will be viewed unfavorably. When marketed properly, however, the
investment in a surgical laser will provide outstanding proﬁtability. The
return on investment can be provided by using the support staﬀ for client
education, by oﬀering laser technology for routine elective procedures and
complex procedures, and by adhering strictly to a fee schedule. Add that
to the truly remarkable results obtained using laser surgical techniques, a
practice will be greatly enhanced.

References

[1] Orman S. The courage to be rich. New York: Riverhead Books; 1999. p. 66.
[2] Schnaars S. Marketing strategy, customers and competition, 2nd edition. New York: The

Free Press; 1998. p. 77.

[3] Paoletti M, Wutchiett C. Sidestep sticker-shock. Veterinary economics 1999;August:48–9.
[4] Glassman G. Craving a new gadget? Veterinary economics, special edition 2000:28–33.

Fig. 2. Checkoﬀ sheet for complex invoicing system.

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J.R. Irwin / Vet Clin Small Anim 32 (2002) 549–567

Soft tissue application of lasers

Timothy L. Holt, DVM*, Fred A. Mann, DVM, MS

Department of Veterinary Medicine and Surgery, University of Missouri-Columbia,

Veterinary Medical Teaching Hospital, 379 East Campus Drive, Columbia, MO 65211, USA

Lasers have served a variety of purposes in industry and medicine for many

years. Little information has been published about the veterinary use of
lasers; however, increasing numbers of veterinarians are incorporating lasers
into their clinical practices. The article will brieﬂy review laser physics and tis-
sue interaction as they relate to soft tissue surgery, describe laser equipment
and accessories, and discuss several veterinary clinical applications.

Carbon dioxide (CO

) laser energy is delivered to tissues through either

collimated or noncollimated directed laser guides. Collimated laser guides
channel and deliver laser energy at a constant power density over distance.
Directed laser guides condense the laser energy to a preset focal distance
resulting in an increase in power density at the tissue surface. Laser energy
rapidly diﬀuses beyond the focal plane resulting in a large drop in power
density over distance.

As mentioned in another article, laser light wavelength and frequency

determine the color of the laser light and the way the laser light interacts with
its target surface [1]. When laser light strikes a surface, it may be reﬂected,
absorbed, scattered, or transmitted [2]. When laser light is absorbed into the
target tissue, it is converted into one or more of the following three types of
energy: thermal, chemical, or acoustic.

The most common lasers currently used in the veterinary clinical setting

are the CO

, neodymium:yttrium aluminum garnet (Nd:YAG), and diode.

The CO

laser is only available in a 10,600-nm wavelength. Although the

Nd:YAG is ﬁxed at 1064 nm, it can be frequency doubled when used as
an energy source for the potassium titanyl phosphate (KTP) laser, which has
a wavelength of 532 nm. The diode laser is available in diﬀering ﬁxed wave-
lengths (805, 820, 950, and 980 nm), determined by the diode chip within
each laser unit.

Vet Clin Small Anim 32 (2002) 569–599

* Corresponding author. Department of Small Animal Medicine, College of Veterinary

Medicine, University of Georgia, Athens, Georgia 30602-7390, USA.

E-mail address: tholt@vet.uga.edu (T.L. Holt).

0195-5616/02/$ - see front matter

PII: S 0 1 9 5 - 5 6 1 6 ( 0 2 ) 0 0 0 0 6 - 2

The CO

and diode lasers are the lasers most commonly marketed to

veterinarians. These lasers are used for incision, excision, and ablation of
soft tissues. The CO

and most solid-state diode lasers function through

photothermal laser-tissue interaction [3]. Water, hemoglobin, melanin, and
some proteins absorb varying wavelengths of laser light resulting in tissue
heating [4]. As the tissue heats, hyperthermia with temperatures of 42

° to

°C destroys blood vessels, resulting in tissue necrosis. As tissue tempera-

tures reach 50

° to 100°C, coagulation occurs, and proteins begin to denature

leading to irreversible tissue damage [5]. Once the tissue is superheated (tem-
peratures exceeding 100

°C), vaporization occurs, and the solid tissue is con-

verted to gaseous vapor and smoke plume [6]. Superheating of tissue with
incomplete vaporization leads to tissue carbonization known as char. This
black char readily absorbs laser energy at any wavelength. Continued lasing
of this black char results in further absorption of laser energy without
tissue ablation and is converted into thermal energy. The thermal energy is
conducted to the surrounding tissues, resulting in hyperthermia and col-
lateral tissue damage. The remaining carbon char also acts as a foreign sub-
stance creating an inﬂammatory response that can negatively aﬀect wound
healing.

or diode lasers—which is better?

Neither a CO

laser nor a diode laser is better for all clinical applications.

There are advantages and disadvantages to both systems. At 10,600-nm
wavelength, the CO

laser is highly absorbed in water, making it very useful

for soft tissue applications [7]. Because of this high absorption, very little
(0.05 to 0.1 mm) [5,7,8], lateral thermal damage occurs, and the result is a
‘‘what you see is what you get’’ application of laser energy to tissue. Most
CO

lasers in veterinary medicine use a noncontact mode, (ie, the tip of the

laser never comes into contact with the target tissue). Newer technology, a
diamond laser scalpel to ﬁt the CO

laser, works in a contact mode to cut

and coagulate with minimal lateral thermal damage.

Most diode lasers sold to practicing veterinarians operate in the range of

805 to 980 nm. Most diode lasers with 600- to 700-nm wavelengths are used
for photodynamic therapy performed in institutional settings [9–13]. Diode
lasers are small, compact units that emit wavelengths that are easily trans-
mitted through small ﬂexible optical ﬁbers, allowing use with most ﬂexible
and rigid endoscopes [14]. The small ﬂexible transmission ﬁbers are made
from glass silica or quartz. Diode laser energy can be applied to target tissue
in a contact or noncontact mode. Vaporization of tissue can be accom-
plished in a noncontact mode; however, this requires higher power settings
and results in a greater depth of thermal damage to surrounding tissue as
compared with the contact mode. When trimmed or terminated in specia-
lized tips, the transmission ﬁbers can be used in a contact mode to cut and

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T.L. Holt, F.A. Mann / Vet Clin Small Anim 32 (2002) 569–599

vaporize [4]. Less thermal damage occurs when used in the contact mode as
compared with the noncontact mode. The laser energy produced by the
diode laser is not as easily absorbed by water as compared with the CO

laser; therefore, there is greater lateral thermal damage compared with the
CO

laser. The shorter wavelength, however, of diode lasers allows better

absorption in hemoglobin and eﬃcient cutting and ablation of vascular tis-
sues. Because of the better absorption by hemoglobin, the diode laser pro-
vides better hemostasis of large vessels than does the CO

laser.

The case applications presented in this article were all performed using a

laser (AccuVet Novapulse LX-20SP, Bothell, WA; Fig. 1). This CO

laser can deliver laser energy in a continuous, chopped (intermittent), or
single pulse wave form. The power range is 2 to 20 W, or 2 to 10 W with
superpulse mode wave conditioning. Continuous wave emits uninterrupted
laser energy at the desired power setting. Chopped or single pulse delivers

Fig. 1. (A) The AccuVet Novapulse LX-20SP CO

laser (AccuVet, Bothell, WA) and (B) smoke

evacuation system.

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T.L. Holt, F.A. Mann / Vet Clin Small Anim 32 (2002) 569–599

multiple or single blocks of laser energy at the desired power setting. Super-
pulse mode conditions the emitted laser energy by producing a continuous
series of microsecond peak power superpulses (subpulses of the continuous,
chopped, or single energy blocks), which average out to the desired power
setting. Although unnoticeable to the laser surgeon, this rapid superpulse
delivery of laser energy to tissue allows microsecond thermal tissue recovery,
resulting in less carbonization of tissue and reduced char production [15–
17]. Superpulse mode can be a real advantage to the novice laser surgeon
in reducing char formation associated with poor lasing technique.

The CO

laser system used here delivers a noncollimated beam through a

hollow reﬂective waveguide, terminating in an autoclavable handpiece ﬁtted
with a tip that directs the laser energy. An assortment of handpieces and tips
are available and may be changed to accommodate diﬀerent surgical
approaches, spot sizes, and focal plane distances. Examples of various hand-
pieces (Fig. 2) and tips (Fig. 3) are illustrated. Because this is a hollow ﬁber
noncontact laser, air is pumped through the tip to prevent occlusion with
tissue debris. This forced air is advantageous in that it facilitates identiﬁca-
tion of tissue planes by elevating tissues as it penetrates them. The tips avail-
able for this CO

laser system vary in diameter from 0.3 to 1.4 mm to allow

choices in cutting beam width from very small, narrow incisions as needed in

Fig. 2. Examples of the handpieces available for the AccuVet Novapulse LX-20SP CO

laser.

(A) ‘‘Gattling gun’’ spatial scanning handpiece. (B) The stainless steel handpiece. (C) Standard
handpiece. (D) angled handpiece. Beside the stainless steel handpiece are two extensions (E, F)
for narrow, deep approaches. One of the extensions (E) is equipped with a metal backstop. Both
extensions have smoke evacuation ports (white arrows) that are connected through an exhaust
port (black arrows) and additional rubber tubing to an external smoke evacuation device (not
shown). The other four handpieces require a separate smoke evacuation system.

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T.L. Holt, F.A. Mann / Vet Clin Small Anim 32 (2002) 569–599

eyelid surgery to large ablative vaporization associated with tumor debulk-
ing or granuloma reduction. In addition, this laser has a spatial scanning
handpiece available that works in a ‘‘gattling gun’’ manner to randomly
distribute laser energy to a more diﬀuse target tissue area at a much faster
rate (Fig. 2).

Surgical technique

Special attention to surgical technique is mandatory for desirable results

and safety. It is important to deliver laser energy perpendicularly from the
handpiece to the target tissue surface to ensure even delivery of laser energy
and to maintain maximum power density. The tip of the laser should be
maintained from 2 to 5 mm from the target tissue, depending on the speciﬁc
handpiece and tip used. There are diﬀering focal planes of the various hand-
piece and tip combinations. The maximum power density for that tip and
power setting is achieved by holding the tip the proper focal distance from
the target tissue. Angling the handpiece relative to the target tissue results in
partial reﬂection of laser energy and an ellipsoid laser energy application
(heel eﬀect) to the target tissue [18]. This angle partially defocuses (diverges)
the energy beam, resulting in an uneven power density and variable cutting
depths.

When incising tissue with the laser, lateral tension perpendicular to the

incision helps the laser separate the tissue and reduces formation of char.
Care must be taken to avoid excessive tension. Excessive tension may con-
tribute to incomplete vaporization and tearing at the incision resulting in

Fig. 3. Examples of the tips used with the standard and angled laser handpieces shown in Fig. 2.
The tips as listed by the manufacturer are: (A) 0.4 mm ﬁne taper metal, which produces a
0.25-mm spot; (B) 0.3 mm metal; (C) 0.4 mm metal; (D) 0.8 mm ceramic; and (E) 1.4 mm metal.

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T.L. Holt, F.A. Mann / Vet Clin Small Anim 32 (2002) 569–599

increased hemorrhage. When working in areas where adequately applied
tension distorts the target tissue, make a guideline using a lower power den-
sity. This guideline can then be followed with an incision performed at a
higher power setting under tension (Fig. 4). Alternately, a dotted guideline
can be made followed by an incision that connects the dots (Fig. 5).

Hemostasis and tissue welding techniques [19,20] can be used by defocus-

ing (diverging) the laser energy. Defocusing laser energy decreases power
density and increases the laser spot applied to the target tissue so that cutting
and vaporization are reduced. Hemostasis occurs with normal laser applica-
tion on vessels with diameters smaller than 1 mm. As the laser cuts tissue,
lateral thermal injury seals nerves, capillaries, and small vessels [21–24].
When defocused, the laser energy drops the power density below the level
necessary for vaporization so that coagulation and protein denaturization
result in hemostasis and tissue welding [19,20,25,26]. The power (Watts), the
tip diameter, and the focal distance are adjusted to change the power density
appropriately for the intended tissue application. In diﬀuse, nonspeciﬁc
hemorrhage, such as on the surface of an excisional biopsy, the laser can

Fig. 4. Hemorrhage-free linear outline (black arrow) of a nosectomy skin incision. This linear
outline is a guideline, which is then traced and deepened to complete the incision. Also
illustrated is laser ablation of the ulcerated surface (white arrow) of a nasal squamous cell
carcinoma.

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T.L. Holt, F.A. Mann / Vet Clin Small Anim 32 (2002) 569–599

be defocused and used in a sweeping motion to ‘‘paint’’ the surface, thus
sealing the microvasculature.

Tissue welding techniques are used to coagulate individual vessels. Inci-

sion closure by suture-free laser tissue welding has been described in ophthal-
mic, urogenital, vascular, and gastrointestinal surgery and has been shown to
provide similar strength in bonding tissue compared with conventional
suture techniques [25,27–29]. A variation of this technique may be applied
on small vessels instead of electrosurgical coagulation or ligatures. The sur-
geon must visualize and expose the vessel, reduce power, defocus the laser,
and ‘‘weld’’ the vessel together by sweeping the long axis of the vessel. One
must be careful to reduce power density enough to weld, but not vaporize
through the target vessel. Larger vessels may require both sides to be welded
because of the limited penetration of the laser energy. Both the diameter and
composition of the vessel wall inﬂuence the success of the weld [30]. Practice
and proﬁciency are needed to determine when a good vascular weld has
occurred. Experience and knowledge of laser–tissue interaction are required
for the laser surgeon to understand when to incorporate vascular welding
versus electrosurgical coagulation or ligation.

Clinical applications

Current clinical uses for the CO

laser can be categorized into three

intended purposes: incision, excision, and ablation. These purposes are
exempliﬁed in the following brief descriptions of procedures that illustrate

Fig. 5. Hemorrhage-free pinpoint laser incisions (arrow) outlining the intended skin margin for
tumor resection.

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T.L. Holt, F.A. Mann / Vet Clin Small Anim 32 (2002) 569–599

some of the laser’s advantages over conventional surgical techniques. The
techniques and settings described are based on university and private clinical
experiences with one particular CO

laser (AccuVet Novapulse LX-20SP).

Power settings and tip selection were based on individual surgical technique
and target tissue composition. Power settings and tip sizes reported here
represent combinations that have worked in these particular applications.
Table 1 presents a chart of the power and tip combinations for diﬀering tis-
sue and procedure applications. The settings in Table 1 are not provided to
create a standard for laser therapy, but rather serve as reference points that
should be modiﬁed relative to the surgeon’s individual experience and needs.
Published reviews and continued research are necessary to expand the lim-
ited, but rapidly growing knowledge base of veterinary laser application.

Integumentary

Skin is one of the more common laser target tissues. Skin has a high water

content with good vascularity, making it an excellent target tissue for CO

laser energy. Because of high absorption of CO

laser energy, very minimal

lateral thermal damage occurs. Wound closure can be performed even with
small intradermal suture patterns with conﬁdence that postoperative dehis-
cence of the suture line will not occur. The noncontact application of the
CO

laser allows initial cutting of tissue without distortion, resulting in more

precise incisions. Noncontact incisions may result in cleaner margins. With
oncologic applications there is no opportunity for tumor seeding caused by
dragging a contaminated scalpel blade through clean tissue.

Dermal incisions

Dermal incisions are typically made with tips less than 0.8-mm diameter.

Tips with a diameter of more than 0.8 mm are usually reserved for ablative
techniques. The most common tip used for incisions on the cases presented
is the 0.4-mm tip. With smaller tip diameters, lower wattages are needed to
provide the appropriate power density for an adequate depth of incision.
Diﬀering tissue hydration, composition, and thickness will vary the require-
ments in power density for proper incision depth. This fact must be taken
into consideration when performing an incision on cat abdominal skin ver-
sus the tail fold of a Shar Pei. If the initial incision fails to penetrate into the
subcutaneous tissue, continue to apply mild tension and retrace the incision
line until the subcutaneous tissue is exposed. Apply a steady and smooth
motion to ensure a consistent depth of cut with reduced char. Avoid sweep-
ing and painting motions when making incisions because they can lead to
irregular depths and widths to the incision line.

Dermal ﬂaps

Dermal ﬂaps are treated in a similar fashion as dermal incisions; the dif-

ference is the undermining and freeing of the ﬂap. An initial guideline may

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T.L. Holt, F.A. Mann / Vet Clin Small Anim 32 (2002) 569–599

be ‘‘drawn’’ on the skin with standard or reduced power in continuous wave,
with or without superpulse mode. The guideline is then traced at standard
dermal settings (wattage) with the skin under tension. Care is taken to
ensure that the skin is completely incised to the subcutaneous tissue. The
ﬂap is grasped atraumatically, and the laser is used with subcutaneous tissue
technique in a sweeping fashion to undermine and elevate the ﬂap back to its
base. Hemorrhage may be controlled by defocusing or vascular welding
techniques.

Lick granuloma

Lick granulomas are treated by ablation with the CO

laser. The initial

granuloma margins are outlined with reduced power and a medium dia-
meter tip in continuous wave, with or without superpulse mode. After com-
plete outline, the tip is changed to maximum diameter with high power, and the
target granuloma tissue is painted and vaporized with continuous wave sett-
ing. As char begins to accumulate, it is wiped away with a saline-moistened
sponge. Keeping char to a minimum is important to ensure minimal ther-
mal conduction and maximal protection of collateral tissue. The target
tissue is continually painted until all the granulomatous tissue is vaporized
and the subcutaneous structures begin to appear. At this point, the laser
power is reduced in half, and the wound surfaced is smoothed. If the wound
is still irregular or continues to hemorrhage, the laser is reduced to minimal
settings, and the surface is retreated. Residual hemorrhage is controlled by
defocusing the laser and painting the hemorrhaging surface. The end result
should be a dull granular appearance to the remaining tissue with very little
char. The wound is allowed to close by second intention healing. Although
experience has shown that most animals will leave this new wound alone, it
should be protected until complete epithelialization has occurred. The
authors’ experiences show a low recurrence rate tracked out to 18 months.
Failures of this technique could be associated with the psychogenic origin
[31–33] of this process or from too conservative of an ablation, leaving gran-
ulation tissue behind. An alternative to this technique is to use the spatial
scanning handpiece (Fig. 2) for faster ablation; however, to date, the
authors have not taken advantage of that tool.

Skinfold resection

Skinfold resection may be performed around the nose, tail, perineum, or

any other area it is observed. Care must be taken when working around the
eye to protect the cornea from primary or reﬂected laser energy. Safety pro-
tocols must also be followed when working around the anus, because gastro-
intestinal methane gas is highly ﬂammable. Those areas should be protected
with moistened sponges and drapes. Never aim the laser in a manner that
leads to potential exposure of cornea or skin through reﬂection or on a com-
pleted incision through the target tissue. As the laser burns through the

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T.L. Holt, F.A. Mann / Vet Clin Small Anim 32 (2002) 569–599

ble

ser

tips

and

power

settin

used

the

auth

ors

ith

Acc

uVet

LX-20

and

LX-20S

lase

(Acc

uVet,

Bothell,

WA)

System

procedure

Tissue

Purpose

Tip

(mm)

Power

(W)

ave

Superpulse

mode

Integumentary

Dermal

incisions/ﬂaps

400

Skin

Incision

0.4

6–8

Continuous

Yes

Subcutaneous

Incision

0.4

5–6

Continuous

Optional

Subcutaneous

Hemostasis

0.4

Fine,

0.3–1.4

2–4

Continuous

Lick

granuloma

removal

kin

Ablation

1.4

12–15

Continuous

Skin

fold

removal

kin

xcision

0.4

Fine,

0.3–1.4

3–8

Continuous

Yes

Subcutaneous

Excision

0.4

Fine,

0.3–1.4

3–6

Continuous

Yes

Skin

mass

resection

Skin,

subcutaneous

Excision

0.4–0.8

6–10

Continuous

Yes

Mammary

mass

resection

Skin,

subcutaneous

Excision

0.4–0.8

6–10

Continuous

Optional

Pinnectomy

Ear

inna

Excision

0.4

6–10

Continuous

Optional

Auricular

ematoma

pinna

Incision

0.4

2–8

Continuous

Lateral

ear

resection;

Skin,

subcutaneous,

Incision

0.4

5–8

Continuous

Optional

ear

canal

ablation

ear

canal

cartilage

Skin,

subcutaneous

Hemostasis

0.4

2–6

Continuous

Optional

Digestive

Maxillectomy;

mandibulectomy

kin,

subcutaneous,

muscle

Incision

0.4

6–8

Continuous

Optional

Glossectomy

Tongue

Excision

0.4

6–8

Continuous

Optional

Tongue

Hemostasis

0.4

2–8

Continuous

Optional

Cytoreduction

oral

ral

neoplasia

Excision

0.4

6–8

Continuous

neoplasia

Ablation

1.4

10–15

Continuous

Celiotomy

100

Skin,

subcutaneous,

linea

alba

Incision

0.4

6–8

Continuous

Optional

Gastropexy

Stomach,

muscle

Incision

0.4

6–8

Continuous

Optional

Pyloroplasty

Stomach,

muscle

Incision

0.4

6–8

Continuous

Optional

Liver

lobectomy/biopsy

Liver

Incision,

excision

0.4

6–8

Continuous

Optional

Liver

Hemostasis

0.4–1.4

2–6

Continuous

Optional

578

T.L. Holt, F.A. Mann / Vet Clin Small Anim 32 (2002) 569–599

Neoplasia

resection/biopsy

Small

intestine

Incision,

excision

0.4

5–6

Continuous

Optional

Respiratory

Nosectomy

Skin,

subcutaneous

Incision,

excision

0.4

6–8

Continuous

Optional

Subcutaneous,

asal

turbinates

Hemostasis

0.4

4–6

Continuous

Optional

Stenotic

nares

correction

Nares

Incision,

excision

0.4

Fine

3–5

Continuous

Soft

palate

resection

Soft

alate

Excision

0.8

5–8

Continuous

Optional

Laryngeal

saccule

resection

aryngeal

saccules

Excision

0.8

ontinuous

Ventriculocordectomy

Skin,

subcutaneous

Incision

0.4

6–8

Continuous

Optional

Vocal

cord

Excision

0.4

5–6

Continuous

Cricoarytenoid

Skin,

subcutaneous

Incision

0.4

5–8

Continuous

Yes

laryngoplasty

Muscle

Incision

0.4

5–6

Continuous

Yes

Subcutaneous,

uscle

Hemostasis

0.4

5–6

Continuous

Yes

Thoracotomy

Skin,

subcutaneous,

muscle

Incision

0.4

5–8

Continuous

Yes

Subcutaneous,

uscle

Hemostasis

0.4

5–6

Continuous

Yes

Urogenital

Cystotomy

Skin,

subcutaneous,

linea

alba

Incision

0.4

6–8

Continuous

Optional

Bladder

Hemostasis

0.4

2–3

Continuous

Optional

Bladder

Incision

0.4

5–6

Continuous

Optional

Urethrostomy

Skin,

subcutaneous

Incision

0.4

Fine,

0.3–0.4

4–6

Continuous

Yes

Urethra

Incision

0.4

Fine–0.3

2–4

Continuous

Yes

Skin,

subcutaneous

Incision

0.4

Fine–0.3

3–5

Continuous

Yes

Perineal

urethrostomy

rethra

Incision

0.4

Fine–0.3

2–3

Continuous

Yes

Penis

xcision

0.4

Fine–0.3

3–5

Continuous

Yes

Skin,

subcutaneous,

linea

alba

Incision

0.4

6–8

Continuous

Optional

Pyometra

terus,

ovaries

Excision

0.4

5–6

Continuous

Optional

Uterine

stump,

ovarian

pedicle

Ablation,

emostasis

0.4

2–6

Continuous

Episioplasty

Skin,

subcutaneous

Incision

0.4

6–8

Continuous

Optional

(continued

page

)

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T.L. Holt, F.A. Mann / Vet Clin Small Anim 32 (2002) 569–599

Table

(con

tinue

)

System

procedure

Tissue

Purpose

Tip

(mm)

Power

(W)

ave

Superpulse

mode

Hemic/lymphatic

Lymph

node

biopsy

Skin,

subcutaneous

xcision,

biopsy

0.4

Fine,

0.3–0.4

4–8

Continuous

Optional

Skin,

subcutaneous

Incision

0.4

6–8

Continuous

Optional

Splenectomy/splenic

biopsy

Spleen

Biopsy

0.4

5–6

Continuous

Optional

Spleen

Hemostasis

0.4

2–6

Continuous

Optional

Endocrine

Thyroidectomy

Skin,

subcutaneous

Incision

0.4

Fine

4–5

Continuous

Optional

Thyroid

Excision,

hemostasis

0.4

Fine

2–3

Continuous

Ophthalmic

Entropion

correction

Eyelid

Incision

0.4

Fine–0.3

2–5

Continuous

Yes

Distichiasis

removal

yelid

Ablation

0.4

Fine

2–3

Single

pulse

Optional

Eyelid

mass

resection

Eyelid

Excision/ablation

0.4

Fine–0.3

2–5

Continuous

Yes

Musculoskeletal

Thoracic/pelvic

limb

mputation

Skin

Incision

0.4

6–8

Continuous

Yes

Subcutaneous,

fascia,

muscle

Incision

0.4

Fine,

0.3–0.4

5–6

Continuous

Yes

Caudectomy

Skin,

subcutaneous,

fascia,

muscle,

disc

Incision

0.4

6–8

Continuous

Optional

Blood

vessel

Hemostasis

0.4

2–6

Continuous

Dewclaw/digit

amputation

Skin,

subcutaneous,

joint

capsule

Incision

0.4

6–8

Continuous

Optional

Arthrotomy

Skin,

subcutaneous,

fascia,

joint

capsule

Incision

0.4

5–8

Continuous

Optional

Cranial

cruciate

repair

Skin,

subcutaneous,

fascia,

joint

capsule

Incision

0.4

5–8

Continuous

Optional

Cranial

cruciate

ligament

removal

Excision,

ablation

0.4

3–5

Continuous

Patellar

luxation

repair

Skin,

subcutaneous,

fascia,

joint

capsule

Incision

0.4

5–8

Continuous

Optional

Femoral

head

and

eck

excision

Skin,

subcutaneous,

fascia,

joint

capsule

Incision

0.4

5–8

Continuous

Optional

All

proced

ures

listed

were

performe

with

the

standar

angled

han

dpiece.

estimate

and

represen

the

minimal

numbe

proce

dures

performe

Hemo

stasis

techn

iques

were

performe

using

the

laser

defoc

used

mode

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T.L. Holt, F.A. Mann / Vet Clin Small Anim 32 (2002) 569–599

target tissue, it will continue on its path and strike the unprotected corneal
or tissue surface. Again, moistened sponges or drapes can be used to protect
tissues in the path of the laser beam.

Skinfold resection is initiated by outlining the tissue fold with the laser

using a small tip and low power technique. Excision is performed with stan-
dard dermal incision and subcutaneous dissection techniques with the small
tip to ensure precision. The tissue is grasped and elevated, and the laser used
to trace along the outline, incising through the tissue. Care should be taken to
maintain a cut perpendicular to the skin surface. The skinfold margin is then
grasped, elevated from the underlying tissue with laser subcutaneous dissec-
tion, and removed. Closure is completed using conventional techniques.

Skin and adnexa neoplasia

Laser surgery is particularly useful for treating cutaneous neoplasia. Non-

contact excision and ablation can greatly reduce the chances of tumor seeding
as compared with conventional excision [34–36]. Tumor seeding may occur
with conventional methods through instrument contact or hemorrhage asso-
ciated with the initial excision. Laser excision creates a vaporized barrier
between the excised tumor and the remaining tissue bed. The laser’s unique
ability to control hemorrhage during resection in combination with this
vaporization barrier reduces wound contamination by tumor cells.

The laser is used to ablate and seal ulcerated tumor surfaces prior to exci-

sion (Figs. 4 and 6). This technique reduces tumor cell contamination to the
remaining tissue before and during tumor resection.

Decreased hemorrhage allows better visibility of excisional margins. Bet-

ter visibility allows the surgeon to use smaller margins and still maintain a
complete resection histologically. Wide margins are typically performed in
conventional oncologic excisions when attempting a surgical cure; laser sur-
gery provides an opportunity for ‘‘curative marginal excision.’’

The laser may be used for either ablation or resection of neoplastic pro-

cesses. Excision should always be chosen over ablation whenever applicable
to ensure adequate margins of resection and histologic evaluation of the
resected tissue. Although laser excision provides an ablated barrier between
the resected and remaining tissue, adequate margin planning and postopera-
tive histopathology are mandatory to ensure excisional success [34,36]. If tissue
is worth the expense of removal, it is worth the expense of histologic evaluation.

The laser surgeon needs to avoid the temptation to vaporize small,

unknown lesions without suﬃcient identiﬁcation of tissue type and the mar-
gins needed for complete resection. Ablative techniques should only be con-
sidered when complete excision with clean margins is not possible. The most
frequent use of this technique is for cytoreductive surgery (tumor debulking)
in preparation for radiation and chemotherapy and for palliative control of
hemorrhage and pain.

Examples of cutaneous neoplastic processes successfully resected with

laser therapy include melanoma, mast cell tumor, squamous cell carcinoma,

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T.L. Holt, F.A. Mann / Vet Clin Small Anim 32 (2002) 569–599

sebaceous adenoma, papilloma, trichoepithelioma, pilomatricoma, and
numerous other cutaneous tumors.

Planning for excision is initiated with cytologic evaluation followed by

further diagnostic tests as indicated by the cytologic results. Identifying the
extent of the neoplastic process assists in planning adequate excisional mar-
gins. During surgery, excisional margins may be marked in two ways: pin-
point incisions (Fig. 5) or a continuous guideline (Fig. 4) around the mass.
The pinpoint incisions are connected or the guideline retraced, and the skin
margin is incised down to the subcutaneous tissue. Once the incision is com-
plete, the margin of the tissue to be excised is grasped, and the laser is used in
a sweeping fashion to undermine between the mass and underlying struc-
tures. Care must be used to ensure that the dissection of the subcutaneous
tissue remains below the tumor margin. Inadvertent incision into the mass
during subcutaneous dissection could result in inadequate marginal resection
or wound contamination. After complete excision, closure of the wound may
be handled in the same manner as with conventional excision. All resected
tissue should be submitted for histopathology.

Fig. 6. Ulcerated surface (arrow) of a tumor after ablation with a CO

laser in defocused

(divergent beam) mode. Ablation in defocused mode seals the wound and reduces the
opportunity for tumor seeding and contamination.

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Sebaceous adenomas and cysts

Sebaceous adenomas and cysts are frequently encountered in skin.

Pedunculated masses may be excised at the skin margin with the remaining
skin margin of attachment ablated to the subcutaneous tissue. Small sessile
lesions should be excised in a circular fashion around the base of the
mass down to the subcutaneous tissue. Laser power settings are similar
to those described with dermal incision techniques and are dependent
on the tip used and thickness of skin involved. Resections should be
performed with the laser in superpulse mode to reduce char production.
Ablations are performed in continuous wave, with or without superpulse
mode. Small ablative craters and circular lesions less than 4 mm in di-
ameter may resolve by second intention healing. Wounds from 4 to 8
mm can be opposed with a single interrupted suture in the same manner
used with dermal punches. Wounds from excisions with a diameter of
more than 8 mm should be treated in the same manner as with conven-
tional surgical excision.

Vaccine-associated sarcomas

Laser therapy can be eﬀective for treating and resecting vaccine-asso-

ciated sarcomas. Medium tip diameters with standard dermal and subcuta-
neous techniques have been used to create clean, visible margins allowing
greater opportunity for elevation and complete removal of these masses.
Superpulse mode decreases char formation and improves visibility during
resection. Larger diameter tips allow wider margins of laser energy ablation
between resected tissue and remaining wound beds. Nontouch resection and
improved visibility through better hemostasis provide greater conﬁdence of
complete excision. Care needs to be taken to evaluate the invasiveness of
these sarcomas, because recurrent masses tend to be more aggressive [37].
Adequate planning should be performed before resection to be conﬁdent
that adequate resection will occur.

Mammary neoplasia and gland resection

Nontouch application allows resection with minimal manipulation of dis-

eased tissue. Decreased hemorrhage associated with the nontouch excision
reduces the potential for tumor seeding [35]. Sealing of nerve ﬁbers and
decreased hemorrhage minimizes postoperative pain and swelling [22]. Laser
settings for skin incision and subcutaneous dissection are similar to settings
previously described. Medium or large diameter tips may be used to increase
the width of the vaporized barrier between excised and remaining tissue,
with the end goal being curative marginal excision [35,36].

Ear

The vascularity of the ear and its associated structures make laser therapy

desirable. Conventional therapy results in hemorrhage that is diﬃcult to

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control without excessive use of electrosurgical coagulation, which results in
postoperative pain and swelling. Incision and ablation with the CO

laser

seals the vasculature, greatly reducing the need for further hemostasis and
minimizing postoperative hemorrhage and swelling. Laser application is
also credited with sealing of nerve ﬁbers, resulting in decreased stimulation
and pain sensation. Incisions made through the thin tissue of the pinna fre-
quently do not require sutures because the laser tends to weld the margins
together as it cuts.

Pinnectomy

Partial or total pinnectomy is performed in response to environmental,

traumatic, or neoplastic conditions involving the pinna. The laser is set on
moderate to high power with a medium tip. It is used to trace along the mar-
gin of a guide clamp to excise the tip. Freehand resection may be performed;
however, placing a guide clamp ensures a smoother margin of resection and
a better cosmetic appearance. Examples of tissue guide clamps are Doyen
intestinal forceps, carmalts, and hemostats. When using a carmalt or hemo-
stat guide, incise proximally to the clamp or guide to eliminate instrument
trauma to the remaining pinna. After excision, sutures are often unnecessary
in the margin because of the tissue welding eﬀect of the laser.

Auricular hematoma

Numerous medical and surgical techniques have been described for treat-

ing auricular hematoma. The CO

laser has been used for incisions into the

rostrolateral surface of the pinna for removal of the hematoma. An advan-
tage is the decreased hemorrhage from the incised margin of the pinna. The
laser is used at low power to outline the shape of an incision described with
the conventional procedure. The power is increased, and the incision is per-
formed by retracing the outline. The hematoma is penetrated and drained,
and the incision is completed with care taken not to damage the cartilage
beneath. Conventional suturing methods are used to obliterate the dead
space and close the wound. Future applications could involve tissue welding
techniques to provide a suture-free method to obliterate dead space and pre-
vent recurrence.

Lateral ear resection and ear canal ablation

The use of traditional surgical methods for lateral ear resections and

ablations can result in extensive hemorrhage and overuse of electrosurgical
coagulation to maintain a visible surgical approach. Laser-assisted ap-
proaches allow excellent visibility through improved hemostasis. Standard
skin and subcutaneous power settings and tip selections are used for the
initial skin incision and soft tissue dissection and continued for incision/
excision of the ear canal. Laser sealing of nerve ﬁbers, less thermal tissue
damage, and better hemostasis are all believed to contribute to decreased

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postoperative pain and swelling. Subjective postoperative evaluations sug-
gest a faster, more pain-free recovery than conventional surgical techniques.

Digestive

The CO

laser is very eﬀective in treating conditions of the gastrointes-

tinal tract because of the high vascularity and water content of this tissue.
Hemostasis is excellent, resulting in reduced use of electrosurgical coagula-
tion. Postoperative pain is reduced, resulting in faster recovery. Laser appli-
cations for gastrointestinal conditions include incision and approach, tissue
excision, tissue ablation, and tissue welding. Currently, with the exception of
tissue welding, all of these techniques are being performed in the clinical set-
ting. Conditions involving oral applications are covered by Bellows in this
issue; therefore, descriptions of procedures involving the oral cavity will
be restricted to neoplastic processes of the jaw and tongue.

Maxillectomy and mandibulectomy

The hemorrhagic tendencies of partial, subtotal, and complete maxillec-

tomies and mandibulectomies can be controlled with laser surgery. The area
to be resected is ﬁrst outlined with the laser. While maintaining tension per-
pendicular to the incision, the laser is continually retraced over the incision
line until bone is contacted. When the laser strikes the bone surface, a yellow
carbon sparking eﬀect will be seen. Current medical CO

lasers will not cut

bone eﬃciently because of the high mineral and low water composition of
bone. As the laser energy is applied, incomplete vaporization from limited
absorption results in carbonization, char deposition, and sparking [38,39].
The bone is incised in a conventional manner with greater visibility and
decreased hemorrhage. Because of the relative size of the supplying vascula-
ture encountered during resection, conservative electrosurgical coagulation
may be necessary when the laser is insuﬃcient to control the hemorrhage.
The laser can also be used to incise and create a buccal ﬂap to cover the
remaining wound. Because of minimal lateral thermal damage, healing will
occur without dehiscence from thermal damage.

The laser oﬀers an exceptional advantage when dissecting through the

heavy jaw musculature, because the musculature does not contract violently
or hemorrhage. Clearer approaches and incisions always result in easier
resections, and easier resections are usually associated with less tissue
trauma and faster recoveries.

Glossectomy

Neoplasia of the tongue is uncommon in dogs and cats, with most oral

cavity tumors arising from the gingiva [40]. Total, subtotal, and partial
glossectomies are occasionally performed to treat neoplastic lesions of the
tongue. The laser is amenable to this procedure, because the tongue is highly
vascular and composed primarily of muscle. Electrosurgical coagulation

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should be available to assist in areas of hemorrhage where laser defocusing
techniques are inadequate. The use of the CO

laser on glossal tissue greatly

enhances visibility and eliminates muscle or nerve stimulation compared
with electrosurgical excision.

Cytoreduction of oral neoplastic tissue

Tumors of the oral cavity (ie, most commonly melanomas, ﬁbrosarco-

mas, and squamous cell carcinomas [40]) can rapidly develop into large,
painful masses. These masses frequently restrict the animal’s ability to eat
or close the mouth; therefore, palliative laser cytoreduction can become
an important part of the treatment protocol. Laser cytoreduction can also
provide adjunctive reduction of tumor burden for radiation therapy and
chemotherapy. The goal with laser cytoreduction is not to excise the com-
plete mass, but rather to reduce size and hemorrhage to a more manageable
state. The laser is used in continuous wave (with or without superpulse
mode), with a medium tip diameter to excise the bulk of the mass. The tip
is changed to a large diameter, and the power is increased to ablate tumor
tissue and shape the remaining wound through smooth paintbrush strokes.
As with lick granuloma resections, power is decreased in a stair-step fashion
to smooth the remaining wound bed. Hemorrhage is controlled through
defocusing techniques. A small amount of char may be left on the exposed
surface of the wound to assist in hemostasis.

Celiotomy

Although laser application in abdominal procedures is primarily reserved

for the celiotomy approach, there are occasional resection, ablation, or
biopsy indications. Advantages of a laser celiotomy approach are reduced
hemorrhage and pain and better visibility. For traditional midline celio-
tomies, however, some surgeons believe the slower approach associated with
laser neutralizes the beneﬁts of hemorrhage and pain control, and conven-
tional incision is chosen instead. Care must be taken to maintain sterility when
working within the abdominal cavity. The hollow waveguide must be pro-
tected from contaminating the sterile surgical ﬁeld. Sterile stockinette, elastic
stretch wrap (Vetrap, 3M Corp.), or sterile endoscopic sleeves may be applied
from the handpiece back over the waveguide to prevent contamination.

Standard tip diameter and power settings are used to incise the skin and

subcutaneous tissue, exposing the linea alba. The linea alba is grasped with
tissue forceps, elevated, and a keyhole incision is made into the abdomen
just caudal to the forceps, but cranial to the umbilicus with the laser angled
cranially. After penetration into the abdomen, a groove director or tissue
forceps is introduced into the abdomen under the linea alba, and laser inci-
sion is completed. Although overpenetration by the CO

laser is not com-

monly a problem, the groove director or tissue forceps provide additional
protection to underlying structures. After adequate exposure, moistened sa-
line sponges can be used to protect underlying tissue.

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Some examples of abdominal procedures amenable to laser application

include gastropexy, pyloroplasty, intestinal resection/anastamosis, liver
lobectomy, tumor resection, and biopsy. Care must be followed when using
laser energy around or in the gastrointestinal tract, because methane gas is
highly ﬂammable. CO

laser therapy has been used in research for suture-free

tissue welding of anastamotic sites [41–43]. Research studies have shown that
suture-free tissue welding produces a bond equal to or greater in strength
than conventional sutures; however, this technique requires advanced tech-
niques, skills, and equipment not currently available in veterinary practice.

Anus and perineum

The perianal and perineal areas are highly vascular and are, therefore,

amenable to laser therapy. Laser therapy oﬀers unique and excitingly new
applications for treatment of persistent problems in this anatomic region.
Details of laser applications to this area are covered by Shelley in this
issue.

Respiratory

Strict adherence to safety protocols must be followed when applying laser

energy to the respiratory tract. Most surgical procedures today are per-
formed with the animals anesthetized with inhalational agents. The presence
of a pure oxygen environment can create safety hazards. The surgeon must
be sure to follow proper safety protocol to protect the endotracheal tube
and airway from exposure and ignition.

Nosectomy

Resection of the nasal planum because of squamous cell carcinoma has

been performed with the CO

laser, with excellent results. Compared with

conventional surgery, the CO

laser provides easier resection with reduced

hemorrhage in a highly vascular region. Reduced hemorrhage results in
cleaner margins with better visibility and less opportunity for inadequate
resection. The laser is used to outline the margin determined by preoperative
diagnostics (Fig. 4). The outline is retraced and deepened into the subcuta-
neous tissue. The laser is then used to incise through the nasal cartilage and
resect the planum. Although electrosurgical coagulation may be necessary to
control persistent hemorrhage, the CO

laser dramatically reduces the need

for electrosurgery, thereby minimizing thermal damage to the remaining tis-
sue. Good exposure of the nasal meatus along with good tissue margin
apposition on wound closure must be ensured to avoid excessive granulation
tissue, cicatrix contraction, and stenosis.

Stenotic nares

Stenotic nares are easily resected even in the smallest of dogs and cats. On

small cats, complete resection of the medial portion the nasal ala (dorsal

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nasal fold) is accomplished by incising from rostral to caudal along a sagittal
plane extending to the nasal alar cartilage. The wound is allowed to heal by
second intention. In larger animals, ventral or lateral alar wedge resections
may be performed. Apposition is then accomplished with cyanoacrylate glue
or with several simple interrupted sutures. Cyanoacrylate glue bonding is
enhanced because of the improved hemostasis and should be delivered using
a tuberculin syringe and needle to prevent excessive application. Laser set-
tings should be low wattage with a small tip diameter, because this proce-
dure requires a ﬁne, controlled incision.

Soft palate resection

Soft palate resection is simpliﬁed with the CO

laser. The animal is placed

in ventral recumbency with its mouth held open. The epiglottis is pushed
upward against the soft palate, and the laser is used with an extended tip
to make pinpoint incisions across the palate, marking the region to be
excised. The endotracheal tube may be momentarily removed for the mea-
suring and marking procedure. Saline-moistened sponges are placed behind
the soft palate in the caudal pharyngeal area. Moistened sponges are also
placed around the endotracheal tube. The caudal margin of the soft palate
is grasped with an Allis tissue forceps or retracted with stay sutures, and the
laser is used in continuous wave superpulse mode to connect the dotted line
and resect the redundant tissue. Once the redundant tissue is excised, the
sponges are removed with care not to disturb the newly resected margin.
No hemorrhage occurs, no sutures are placed in the margin, and minimal
swelling is noted as compared with conventional excision. An alternative
to sponge placement in the caudal pharyngeal area is use of a special stain-
less steel handpiece/tip combination that incorporates its own metal back-
ground, shielding the tissue behind it from the eﬀects of the laser energy
(Fig. 2). If everted laryngeal saccules should accompany the elongated
palate, they may be resected by grasping them with tissue forceps and per-
forming a crescent excisional resection in continuous wave superpulse
mode.

Ventriculocordectomy

Ventriculocordectomy has been performed with the CO

laser with no

return of vocalization in seven cases followed from 0 to 3 years. A ventral
cervical approach is used to expose the larynx. Skin and subcutaneous tis-
sues are dissected with the laser at standard settings. The larynx is exposed
and entered. The vocal cords are located with conventional dissection to
protect the endotracheal tube beneath. The endotracheal tube is packed and
protected with saline-soaked sponges. The vocal cords are grasped with tis-
sue forceps and excised with the laser set on continuous wave, with or with-
out superpulse mode. The area should be observed for hemostasis and
closed in a conventional manner. Swelling and hemorrhage are minimal, and
recovery is rapid.

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Cricoarytenoid laryngoplasty

Cricoarytenoid laryngoplasty for treatment of laryngeal paralysis can be

performed as a laser-assisted procedure. The CO

laser is used in continuous

wave superpulse mode to make the approach. A paramedian incision is
made through the skin and into the subcutaneous tissues. After exposure
of the thyroid and cricoid cartilages, the thyropharyngeal muscle is isolated,
and the laser is used to transect it near the dorsal caudal edge of the thyroid
cartilage. After retracting the thyroid cartilage laterally, the cricothyroid
junction is incised conventionally. Conventional blunt dissection is used to
pass a hemostat under the cricoarytenoideus dorsalis muscle at the level
of the cricoarytenoid articulation. The laser is used to incise the cricoaryte-
noideus dorsalis muscle over the hemostat, resulting in exposure of the cri-
coarytenoid articulation. Hemorrhage is controlled through laser defocusing.
The procedure is then completed as described in literature. The laser provides
better visualization, thus allowing easier landmark identiﬁcation in an area
with many vital structures. Incising muscle with the laser results in a smooth,
hemorrhage-free incision. Muscle contraction does not occur during laser
incision because muscle and nerve tissue are not stimulated.

Thoracotomy

The CO

laser’s function in intrathoracic surgery in clinical veterinary

practice has been currently limited to the surgical approach. The main bene-
ﬁts of the CO

laser are decreased hemorrhage, better visibility, and reduced

trauma. The lateral approach is most commonly used in veterinary medicine
and requires multiple muscular incisions. Laser incision reduces muscular
hemorrhage and seals nerve endings. Less hemorrhage results in decreased
use of electrosurgical coagulation. Postoperative discomfort and swelling are
also minimized. The laser is used in continuous wave superpulse mode to
make the skin incision, dissect the subcutaneous tissue, and incise muscle
bodies with minimal hemorrhage and stimulation. When the thoracic pleura
is reached, conventional methods are used to enter the thoracic cavity and
complete the procedure.

Urogenital

Urogenital laser applications in humans and animals have included

cystotomy, ureteral implantation, and prostatectomy [27,28,44,45]. De-
creased use of electrosurgical coagulation, improved hemostasis, increased
visibility, and future capabilities for tissue welding are all important factors
that give laser use a distinct advantage over conventional techniques in uro-
genital surgery.

Cystotomy

A conventional or laser celiotomy approach is performed. Once the

abdominal cavity is entered, the bladder should be isolated and packed oﬀ

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with saline-moistened sponges. The bladder incision is outlined with the laser
defocused at low power settings in continuous wave (with or without super-
pulse mode) to seal or weld the vasculature along the incision on the surface
of the bladder. Two stay sutures are placed at each end of the outline. Two lat-
eral stay sutures may also be placed. With the two cranial and caudal stay
sutures under tension, the outline on the bladder wall is incised with the laser
at subcutaneous tissue settings. The incision can be made through the bladder
wall with minimal concern of deeper tissue damage, as the urine absorbs
excess laser energy. Laser incision into the bladder reduces hemorrhage
and allows better visualization of bladder mucosa. The laser can be used
for excision or palliative ablation of neoplastic tissue within the bladder.
Current research is studying suture-free tissue welding closure that may
result in a tighter, stronger seal at the incision site with no suture nidus for
inﬂammation [45].

Urethrostomy

A red rubber catheter is placed into the urethra to facilitate identiﬁcation

of the lumen. Laser skin incision is performed with a small diameter tip in
continuous wave superpulse mode. The subcutaneous fat is incised down
to the urethra. The laser is reduced in power, and the ﬁnal incision is made
into the lumen of the urethra by incising over the red rubber catheter. Care
should be taken not to melt the surface of the catheter. Twisting of the
catheter during urethral incision may help reduce focal laser melting of the
catheter. Creation of the new urethral stoma can now be performed by con-
ventional suturing methods with excellent visibility.

Perineal urethrostomy

Perineal urethrostomy is performed with the small laser tips and contin-

uous wave superpulse mode for skin incision and subcutaneous dissection.
The laser is reduced to low power settings to dissect the penile pelvic attach-
ments from their ventral ischial origin. Care must be taken to avoid the pel-
vic urethra. Once the penis and pelvic urethra are freed, conventional
dissection is used to remove the retractor penile muscle to avoid penetration
or damage to the urethra. A ﬁne probe is inserted into the urethra, and the
laser is used at low power settings to incise over the probe proximally to the
pelvic urethra. The tip of the penis is resected with the laser set on dermal
incision settings in continuous wave without superpulse. The laser should
provide enough hemostasis to seal the distal cavernous body. The procedure
is completed by conventional suturing methods.

Pyometra

Laser application for surgical treatment of pyometra is primarily restricted

to the celiotomy approach. The laser can be used, however, for incising the
pedicles and uterine body to reduce abdominal contamination. After removal

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of the uterus and ovaries, the ends of the pedicles and uterine stump are
ablated with a defocused technique at low power and continuous wave.

Episioplasty

The CO

laser is used to maximize functional cosmetic reconstruction of

the dermis. Decreased hemorrhage and no tissue distortion allow much
greater precision in planning incisional placement. Enhanced visibility leads
to excellent results. Standard skin incision settings are used with a small to
medium diameter tip and continuous wave superpulse mode. The subcuta-
neous dissection is performed with similar settings. Conventional methods
are used for closure.

Hemic and lymphatic

Lymph node biopsy

Lymph node biopsies and resections can be easily performed with the

laser. Standard power and tip combinations are used to incise through

the skin and subcutaneous tissue and to expose the lymph node. Hemostasis
may be accomplished through defocusing techniques. Because lymph nodes
are frequently located in areas with vital vascular structures, the use of
the CO

laser for incision and dissection of the soft tissue structures during

the approach and excision dramatically decreases hemorrhage and allows for
better visualization and gross evaluation of lymphoid tissue.

Splenectomy and splenic biopsy

Splenectomies can be performed as laser-assisted procedures. Hemostasis

of the large vasculature of the spleen should be accomplished using conven-
tional electrosurgical coagulation and suture, hemoclip, and staple ligation.
The laser can contribute to a drier, less painful approach into the abdomen.
The laser can be used with guillotine suture placement to make excisional
wedge biopsies through the parenchyma of the spleen. Hemorrhage on the
surface is then controlled with defocusing techniques.

Endocrine

Thyroidectomy

The CO

laser has been used for thyroid tissue resection as therapy for

feline hyperthyroidism when radioiodine (

131

I) therapy is unavailable. The

initial skin incision is made on the ventral cervical midline with a small di-
ameter tip. Conventional dissection is used to expose the thyroid tissue. The
laser is reduced to minimal power and is used to ‘‘tease’’ the thyroid tissue
from its vascular bed. If hemorrhage occurs, the laser is defocused to coagu-
late or weld the vasculature. With large thyroid masses, hemorrhage may be
controlled by defocusing the laser and by using welding techniques on larger
vessels entering the mass before excision.

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Ophthalmic

The primary ophthalmic application for CO

laser therapy in veteri-

nary medicine has been restricted to treatment of the eyelids and associated
structures.

Entropion

Entropion surgery requires good subjective evaluation and precise surgi-

cal skill to achieve good results. The laser provides precision with excellent
visibility. The eyelids are a highly vascular tissue that easily distorts and
hemorrhages with conventional blade incisions. The nontouch feature of
the CO

laser allows the surgeon to incise without pulling and distorting

the eyelid tissue [46]. The hemostasis associated with laser incisions aﬀords
the surgeon dramatically increased visibility during incision. These two fac-
tors contribute to an accurate repair with excellent results [47]. Entropion
incisions are made with ﬁne diameter tips and low power settings in contin-
uous wave superpulse mode. Depending on the degree of entropion present,
a single incision may be made and allowed to heal by second intention or a
wedge/ellipse can be removed and the wound closed conventionally. Like
with traditional entropion surgery, success is dependent on a certain
amount of skill and expertise necessary to adequately evaluate and correct
this problem. Extreme care must always be taken when incising around the
eye to protect the surface of the cornea from direct and reﬂected laser
energy, because it is highly susceptible to damage from exposure (Fig. 7).
Always keep a saline-moistened sponge between the laser source and the
cornea, and never position the beam in a manner that could result in cor-
neal exposure.

Distichiasis

Although distichiasis is treatable with CO

laser therapy, conventional

cryosurgical treatment is a more eﬃcient and dependable form of therapy
[48,49]. In treating minor cases of distichiasis, the lid margin is everted with
a chalazion forceps, and the distichia is isolated. Extreme care is taken to
protect the cornea. The laser is used in single pulse wave (with or without
superpulse mode) with minimal power and a small diameter tip. The single
pulse wave oﬀers a single, short duration block of laser energy with each
depression of the foot pedal. This approach helps prevent overexposure to
the delicate eyelid tissue. The laser is aimed away from the cornea and
focused at the root of the distichia hair. The root is ablated at repeated inter-
vals until the distichiasis is removed. Care is taken not to penetrate through
the lid. The wound is allowed to close by second intention healing. Conven-
tional medical therapy should be incorporated for postoperative recovery.

Eyelid masses

Wedge resections, block resections, and ablations of eyelid masses using

the CO

laser result in hemorrhage-free margins that are easy to evaluate

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and close [50]. The CO

laser aﬀords precision through visualization and

minimal tissue distortion during excision [51]. This allows for accurate
apposition of wound margins resulting in good function and cosmetic
appearance. The mass to be resected is isolated with a chalazion clamp. A
saline-moistened sponge is placed behind the chalazion clamp. A ﬁne di-
ameter tip, low power setting, and continuous wave with superpulse mode
are selected. The mass is resected against the solid back of the chalazion
clamp with care not to aim the laser toward the cornea. The clamp is re-
moved, and the wound is closed by conventional methods. For a small pe-
dunculated mass on the lid margin, the mass is isolated in the chalazion clamp
and incised oﬀ the margin of the lid. After excision, the wound bed at the lid
margin is ablated to prevent regrowth.

Musculoskeletal

The CO

laser is not absorbed well in bone because of its low water and

high mineral composition. When the CO

laser is applied to bone, there is

incomplete vaporization, and char is formed on the bone surface [38]. Con-
tinued application of laser energy of this char results in yellow spark forma-
tion. Although not useful for cutting bone, the CO

laser is very useful for

making approaches to bony structures and for incising cartilage and liga-
ments. Although laser approaches tend to be slower than conventional
methods, they result in better hemostasis and exposure. Postoperative recov-
ery subjectively appears to be faster, most likely because of decreased pain,

Fig. 7. Thermal damage to the cornea and eyelid from improper laser technique. The arrows
point to corneal ulcers resulting from thermal damage by CO

laser exposure. (Courtesy of

E. Guilliano, DVM, University of Missouri, Columbia, MO.)

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swelling, and hemorrhage. Procedures performed include thoracic and pel-
vic limb amputations, caudectomies, and dewclaw and digit amputations.
Laser-assisted orthopedic procedures include cranial cruciate ligament
repair, patellar luxation repair, femoral head and neck excision, and fracture
repair. Current research is ongoing to evaluate laser usefulness in methyl-
methacrylate removal and intervertebral disc fenestration as well as combin-
ing a CO

laser with an erbium:YAG laser for bone applications [52–54].

Thoracic and pelvic limb amputations

Thoracic and pelvic limb amputations are performed with ease and excel-

lent visibility using the CO

laser. Dermal incisions and subcutaneous dis-

section are made with standard settings and tip selection. Fascial planes
are easily and eﬀectively incised using subcutaneous tissue techniques with
a small to medium tip. After initial penetration of a fascial plane, air
expelled through the tip of the laser will dissect under the fascial plane and
elevate it. The continued incisional vaporization with the fascia under ten-
sion while incorporating a smooth, steady stroke results in complete fascial
plane incision with minimal or no underlying tissue damage. A groove direc-
tor or hemostat may be passed under the fascia and used as a guide for pro-
tecting the underlying structures during dissection. Muscle bellies are
isolated and incised at medium power and small to medium tip diameter.
As muscle bellies are isolated and incised, no nerve or muscle stimulation
occurs. Hemorrhage is minimized. Large vessels that are not amenable to
vessel welding with defocusing techniques should be controlled with electro-
surgical coagulation or ligatures. Postoperative recovery subjectively
appears to be faster and more comfortable because of decreased pain, swell-
ing and hemorrhage.

Caudectomy

Tail amputations are made easy with the CO

laser. Tourniquet use is

commonly unnecessary. Less skin distortion occurs when making the initial
incision, resulting in a better cosmetic appearance. The initial skin incision is
made with standard dermal settings. Dissection is completed through the
subcutaneous tissue. The skin is retracted cranially, and the tail is disarticu-
lated through the intervertebral space with the laser at medium power in
continuous wave. Hemorrhage may occur from the paired lateral caudal
arteries or from the median caudal artery ventrally. Defocusing and ablating
are usually suﬃcient to eliminate hemorrhage. With high amputations in
large breed dogs, however, isolation and hemostasis through tissue welding
techniques, electrosurgical coagulation, or ligature placement should be per-
formed before transection of the medial caudal artery. The skin margin may
be opposed with a continuous intradermal suture pattern to avoid suture
exposure. Intradermal closure combined with laser resection decreases post-
operative pruritis and swelling and helps reduce patient-inﬂicted trauma to
the surgical area.

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Dewclaw resection and digit amputation

Laser dewclaw resections and digit amputations allow hemorrhage-free

dissection without a tourniquet, resulting in minimal use of electrosurgical
coagulation, excellent visibility, and minimal tissue trauma. Typical dermal
power and tip selections are used. The dewclaw is grasped and abducted
with an Allis tissue forceps. An elliptic incision is made around the dewclaw
from the distal margin of the skin web between the ﬁrst digit and the meta-
carpus or metatarsus and continued proximally to 1 cm behind the joint of
the ﬁrst phalanx and the metacarpus or metatarsus. The laser is then used to
dissect the subcutaneous tissue while abducting and exposing the phalanx
proximally to the metacarpo- or metatarsophalangeal joint. The laser is used
to disarticulate the metacarpo- or metatarsophalangeal joint from the
exposed medial surface laterally toward the metacarpus or metatarsus. The
digit is further elevated, and the laser is used to transect any laterally
attached joint capsule and soft tissue, releasing the abducted digit. The laser
is defocused to control hemorrhage from the dorsal common or axial pal-
mar digital arteries. With large or multiple digit amputations, electrosurgical
coagulation and ligatures may be needed to adequately provide hemostasis.
For a smoother closure, the laser is used to incise the remaining joint capsule
and periosteum on the medial surface of the ﬁrst metacarpal or metatarsal
bone. The condyle and metaphysis of the ﬁrst metacarpal or metatarsal bone
are exposed, and a rongeur is used to remove the condyle, resulting in a
smoother, more cosmetic resection. Routine closure is performed, and a soft
padded bandage is applied. The surgeon must be conservative in the amount
of skin resected with the digit to ensure adequate wound closure with mini-
mal suture line tension.

Arthrotomy

Standard dermal and subcutaneous power settings and tips are used.

Hemorrhage is controlled using defocusing techniques. Fascial planes are
easily and eﬀectively incised using techniques described with limb amputa-
tion. Capsulotomy is performed with a keyhole incision into the joint. Then,
if possible, a groove director or hemostat is introduced and used as an inci-
sion guide, protecting joint structures below as the keyhole incision is
extended. The use of the laser to make joint capsule incisions reduces cap-
sular hemorrhage and increases visibility.

Cranial cruciate ligament repair

The previously described techniques outlined for use in limb amputation

and arthrotomy are incorporated for the approach to repair a ruptured
cranial cruciate ligament. Additionally, the laser can be useful in tissue de-
bridement within the exposed stiﬂe. The laser is very eﬀective in resecting and
ablating the remaining ﬁbers of the cranial cruciate ligament. Low-power
settings and continuous wave are selected. The origin of the cranial cruciate
ligament on the caudomedial aspect of the lateral condyle is located and

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ablated, and the remnant ﬁbers are removed. This approach is repeated for
the insertion on the cranial intercondyloid area of the tibia. With adequate
exposure, similar techniques can be used to excise meniscal tears. Care must
be taken when aiming to ensure that no aberrant damage is done to the cau-
dal cruciate ligament, articular cartilage, or other vital structures within the
joint.

Patellar luxation repair

Standard power settings are used for dermal and subcutaneous dissec-

tion. Incisions through the fascia and joint capsule are performed as
described earlier. Wedge sectioning of the trochlea and elevation of the tibial
tuberosity are bone-cutting techniques that currently require conventional
methods. Although the laser surgical approach for correction of patellar
luxation is slower than conventional approaches, it yields a much cleaner
surgical ﬁeld. This allows better exposure of structures and landmarks for
more precision in repair. Postoperatively, there is less tissue swelling and
hemorrhage and a faster recovery than with conventional patellar luxation
surgery.

Femoral head and neck excision

Femoral head and neck excision is a commonly performed procedure for

which the laser can be used to yield a clean approach with good visualiza-
tion of vital structures surrounding the coxofemoral joint. Laser-assisted
approach reduces hemorrhage, making it easier to locate and isolate vital
structures. Compared with conventional femoral head and neck excision,
laser provides better precision in incising skin, muscle, and joint capsule,
which results in less tissue trauma with better exposure and facilitates a com-
plete excision of the head and neck. Recovery can be faster as a result of
decreased tissue trauma, swelling, and hemorrhage. Standard dermal power
and tip diameter are selected. Subcutaneous tissue, fascia, muscle, and joint
capsule are incised at power settings as described for other musculoskeletal
techniques (Table 1). Currently, the ostectomy must be performed with con-
ventional techniques.

Conclusion

Although the laser incises at slower speeds than conventional methods,

laser surgery oﬀers better hemostasis and visibility, less postoperative swell-
ing, and decreased postoperative pain. In certain procedures, better hemo-
stasis and visibility will reduce overall surgical time. As more clients and
owners become familiar with these advantages, the laser will become a fre-
quently requested surgical tool. Although many clinical applications of laser
surgery have been discussed, this article only begins to address the many
potential applications. Research and published case studies are necessary

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to establish a better understanding of laser–tissue interaction and future
applications.

Variability of individual surgical technique and tissue composition has a

dramatic eﬀect on the outcome of a procedure and makes setting up standard-
ized laser techniques a diﬃcult chore. The settings and tips described in the
text and Table 1 represent what has worked in the authors’ hands using one
particular CO

laser. These techniques should be taken, adapted, and modi-

ﬁed according to the individual surgeon’s expertise. Truly mastering laser
application involves a thorough knowledge of the relationship between laser
energy and tissue interaction. Laser surgery should not be attempted in prac-
tice until the surgeon is familiar with laser–tissue interaction concepts.

Future laser use within clinical practice will include new and exciting

methods for enhancing surgical procedures. Future research applications
look to make tissue welding and bioactive stimulation available to the clin-
ical arena. Many more such applications are sure to be developed as laser
technology is adapted to clinical needs.

References

[1] Hitz CB. An overview of laser technology. In: Understanding laser technology: an intuitive

introduction to basic and advanced laser concepts, 2nd edition. Tulsa (OK): PennWell
Publishing; 1991. p. 1–22.

[2] Welch AJ, van Gemert MJC. Introduction to medical applications. In: Welch AJ, van

Gemert MJC,

editors. Optical-thermal response of laser-irradiated tissue. New York:

Plenum Press; 1993. p. 609–18.

[3] Jacques SL. Laser-tissue interactions. Photochemical, photothermal, and photomechanical.

Surg Clin North Am 1992;72:531–58.

[4] Katzir A. Medical lasers. In: Lasers and optical ﬁbers in medicine. San Diego (CA):

Academic Press; 1993. p. 15–58.

[5] Pearce J, Thomsen R. Rate process analysis of thermal damage. In: Welch AJ, van Gemert

MJC, editors. Optical-thermal response of laser-irradiated tissue. New York: Plenum Press;
1995. p. 561–606.

[6] Lucroy MD, Bartels KE. Using biomedical lasers in veterinary practice. Vet Med

2000;95:4–9.

[7] Katzir A. Applications of lasers in therapy and diagnosis. In: Lasers and optical ﬁbers in

medicine. San Diego (CA): Academic Press; 1993. p. 59–106.

[8] Treat MR, Oz MC, Bass LS. New technologies and future applications of surgical lasers.

The right tool for the right job. Surg Clin North Am 1992;72:705–42.

[9] Klein MK, Roberts WG. Recent advances in photodynamic therapy. Comp Cont Educ

Small Anim 1993;15:809.

[10] Lucroy MD, Edwards BF, Madewell BR. Veterinary photodynamic therapy. J Am Vet

Med Assoc 2000;216:1745–51.

[11] Lucroy MD, Magne ML, Peavy GM, et al. Photodynamic therapy in veterinary medicine:

current status and implications for applications in human disease. J Clin Laser Med Surg
1996;14:305–10.

[12] Magne ML, Rodriguez CO, Autry SA, et al. Photodynamic therapy of facial squamous cell

carcinoma in cats using a new photosensitizer. Lasers Surg Med 1997;20:202–9.

[13] McCaw DL, Pope ER, Payne JT, et al. Treatment of canine oral squamous cell carcinomas

with photodynamic therapy. Br J Cancer 2000;82:1297–9.

597

T.L. Holt, F.A. Mann / Vet Clin Small Anim 32 (2002) 569–599

[14] Katzir A. Single optical ﬁbers. In: Lasers and optical ﬁbers in medicine. San Diego (CA):

Academic Press; 1993. p. 107–39.

[15] Bryant GL, Davidson JM, Ossoﬀ RH, et al. Histologic study of oral mucosa wound

healing: a comparison of a 6.0- to 6.8-micrometer pulsed laser and a carbon dioxide laser.
Laryngoscope 1998;108:13–7.

[16] Fortune DS, Huang S, Soto J, et al. Eﬀect of pulse duration on wound healing using a CO

laser. Laryngoscope 1998;108:843–8.

[17] Lanzafame RJ, Naim JO, Rogers DW, et al. Comparison of continuous-wave, chop-wave,

and super pulse laser wounds. Lasers Surg Med 1988;8:119–24.

[18] Nishioka NS, Jacques SL, Richter JM, et al. Reﬂection and transmission of laser light from

the esophagus: the inﬂuence of incident angle. Gastroenterology 1988;94:1180–5.

[19] Bass LS, Treat MR. Laser tissue welding: a comprehensive review of current and future

clinical applications. Lasers Surg Med 1995;17:315–49.

[20] Oz MC, Bass LS, Chuck RS, et al. Strength of laser vascular fusion: preliminary obser-

vations on the role of thrombus. Lasers Surg Med 1990;10:393–5.

[21] Haugland LM, Collier MA, Panciera RJ, et al. The eﬀect of CO

laser neurectomy on

neuroma formation and axonal regeneration. Vet Surg 1992;21:351–4.

[22] Montgomery TC, McNaughton SD. Investigating the CO

laser for plantar digital

neurectomy in horses. Lasers Surg Med 1985;5:515–7.

[23] Palesty JA, Zahir KS, Dudrick SJ, et al. Nd:YAG laser surgery for the excision of pilonidal

cysts: a comparison with traditional techniques. Lasers Surg Med 2000;26:380–5.

[24] Zimmermann I, Stern J, Frank F, et al. Interception of lymphatic drainage by Nd:YAG

laser irradiation in rat urinary bladder. Lasers Surg Med 1984;4:167–72.

[25] Barak A, Eyal O, Rosner M, et al. Temperature-controlled CO

laser tissue welding of

ocular tissues. Surv Ophthalmol 1997;42(Suppl 1):S77–81.

[26] Bass LS, Moazami N, Pocsidio J, et al. Changes in type I collagen following laser welding.

Lasers Surg Med 1992;12:500–5.

[27] Kirsch AJ, Dean GE, Oz MC, et al. Preliminary results of laser tissue welding in extra-

vesical reimplantation of the ureters. J Urol 1994;151:514–7.

[28] Lobel B, Eyal O, Kariv N, et al. Temperature controlled CO(2) laser welding of soft tissues:

urinary bladder welding in diﬀerent animal models (rats, rabbits, and cats). Lasers Surg
Med 2000;26:4–12.

[29] McNally KM, Sorg BS, Welch AJ, et al. Photothermal eﬀects of laser tissue soldering. Phys

Med Biol 1999;44:983–1002.

[30] Kung RT, Stewart RB, Zelt DT, et al. Absorption characteristics at 1.9 microns: eﬀect on

vascular welding. Lasers Surg Med 1993;13:12–7.

[31] Eckstein RA, Hart BL. Treatment of canine acral lick dermatitis by behavior modiﬁcation

using electronic stimulation. J Am Anim Hosp Assoc 1996;32:225–30.

[32] White SD. Naltrexone for treatment of acral lick dermatitis in dogs. J Am Vet Med Assoc

1990;196:1073–6.

[33] Wynchank D, Berk M. Fluoxetine treatment of acral lick dermatitis in dogs: a placebo-

controlled randomized double blind trial. Depress Anxiety 1998;8:21–3.

[34] Lanzafame RJ, Qiu K, Rogers DW, et al. Comparison of local tumor recurrence following

excision with the CO

laser, Nd:YAG laser, and Argon Beam Coagulator. Lasers Surg Med

1988;8:515–20.

[35] Lanzafame RJ, Rogers DW, Naim JO, et al. Reduction of local tumor recurrence by

excision with the CO

laser. Lasers Surg Med 1986;6:439–41.

[36] Lanzafame RJ, Rogers DW, Naim JO, et al. The eﬀect of CO

laser excision on local tumor

recurrence. Lasers Surg Med 1986;6:103–5.

[37] Weigand CM, Brewer WG. Vaccination-site sarcomas in cats. Compend Contin Educ Pract

Vet 1996;18:869–75.

[38] Rayan GM, Pitha JV, Edwards JS, et al. Eﬀects of CO

laser beam on cortical bone. Lasers

Surg Med 1991;11:58–61.

598

T.L. Holt, F.A. Mann / Vet Clin Small Anim 32 (2002) 569–599

[39] Rayan GM, Stanﬁeld DT, Cahill S, et al. Eﬀects of rapid pulsed CO

laser beam on cortical

bone in vivo. Lasers Surg Med 1992;12:615–20.

[40] Klausner JS, Hardy RM. Alimentary tract, liver, and pancreas. In: Slatter D, editor. Text-

book of small animal surgery, 2nd edition. Philadelphia: W. B. Saunders; 1993. p. 2088–105.

[41] Cespanyi E, White RA, Lyons R, et al. Preliminary report: a new technique of enterotomy

closure using Nd:YAG laser welding compared to suture repair. J Surg Res 1987;42:147–52.

[42] Farag A, Nasr SE, el Ashkar MF. Laser welding of everted enterotomies in rats. Eur J Surg

1995;161:735–9.

[43] McCue JL, Phillips RK. Sutureless intestinal anastomoses. Br J Surg 1991;78:1291–6.
[44] Kuntzman RS, Malek RS, Barrett DM, et al. High-power (60-watt) potassium-titanyl-

phosphate laser vaporization prostatectomy in living canines and in human and canine
cadavers. Urology 1997;49:703–8.

[45] Lobik L, Ravid A, Nissenkorn I, et al. Bladder welding in rats using controlled temperature

laser system. J Urol 1999;161:1662–5.

[46] Lieb WE, Klink T, Munnich S. CO

and erbium YAG laser in eyelid surgery. A com-

parison. Ophthalmologe 2000;97:835–41.

[47] Morrow DM, Morrow LB. CO

laser blepharoplasty. A comparison with cold-steel

surgery. J Dermatol Surg Oncol 1992;18:307–13.

[48] Huneke JW. Argon laser treatment for trichiasis. Ophthal Plast Reconstr Surg 1999.

1992;8:50–5.

[49] Slatter D. Principles of opthalmic surgery. In: Slatter D, editor. Textbook of small animal

surgery, 2nd edition. ;8:Philadelphia: W.B. Saunders; 1993. p. 1142–77.

[50] Lapid-Gortzak R, Lapid O, Monos T, et al. CO

-laser in the removal of a plexiform

neuroﬁbroma from the eyelid. Ophthalmic Surg Lasers 2000;31:432–4.

[51] Kaplan I, Kott I, Giler S. The CO

laser in the treatment of lesions of the eyelids and peri-

orbital region. J Clin Laser Med Surg 1996;14:185–7.

[52] Nerubay J, Caspi I, Levinkopf M, et al. Percutaneous laser nucleolysis of the intervertebral

lumbar disc. An experimental study. Clin Orthop 1997;42–4.

[53] Scholz C, Matthes M, Kar H, et al. Removal of bone cement with laser. Biomed Tech (Berl)

1991;36:120–8.

[54] Sherk HH, Lane G, Rhodes A, et al. Carbon dioxide laser removal of polymethylmetha-

crylate. Clin Orthop 1995;67–71.

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Feline onychectomy and elective

procedures

William Phillip Young, DVM

Chevington Animal Hospital, 11875 Pickerington Road, Pickerington, OH 43147, USA

The inherent characteristics of the carbon dioxide (CO

) laser make it ideal

for many types of surgery. The laser beam is composed of high-energy
photons. These photons are the emitted radiation that produces the unique
incisional characteristics of the CO

laser. The surgeon guides the laser beam

to the desired target in the surgical ﬁeld, not unlike a scalpel. There is no con-
tact between the handpiece and the surgical site. At a given power setting, the
cutting action of the laser beam is directly proportional to the water content
of the tissues and the proximity of the laser beam to the target tissues.

The far-infrared beam of the CO

laser incises tissue by virtue of the exci-

tation of intracellular water molecules. The rapid change of the water mole-
cules from a liquid to a gaseous state causes tremendous expansion of the
cell membrane. The change of the state of matter of the water molecules
occurs so quickly that the cell explodes on vaporization of the water. This
cellular vaporization is the mechanism that gives the CO

laser its unique

cutting characteristics and precision, which can be of tremendous beneﬁt
when performing laser surgery.

Elective surgery using the CO

laser

The CO

laser is an extremely versatile piece of equipment. With few

exceptions, it can be used in almost the same manner as a scalpel, but with-
out the accompanying hemorrhage. A reduction in postoperative pain and
swelling make the CO

laser an excellent tool for consideration when per-

forming routine surgery. Routine elective surgeries frequently performed
with a CO

surgical laser by the author are as follows: canine and feline cas-

trations, dewclaw removal, feline onychectomies, and tail amputations.

Vet Clin Small Anim 32 (2002) 601–619

E-mail address: chevanhosp@aol.com (W.P. Young).

0195-5616/02/$ - see front matter

PII: S 0 1 9 5 - 5 6 1 6 ( 0 2 ) 0 0 0 0 7 - 4

Feline laser onychectomy

The CO

surgical laser is perfectly suited for feline onychectomy. When

performed using conventional surgical techniques, this elective procedure
is fraught with complications. Complications, such as excessive hemorrhage,
pain, inﬂammation, swelling, and infection, are greatly reduced by using the
laser. Also eliminated are the complications arising from the use of tourni-
quets and bandages to control the hemorrhage associated with conventional
declaw surgery. When performed correctly, a laser onychectomy should not
require the use of tourniquets, bandages, or surgical wound closure.
Twenty-four hours after surgery, the patient should be ambulatory and
exhibiting minimal pain or swelling at the surgical sites. This is the gold
standard of a successful laser onychectomy.

Feline CO

laser onychectomy by resection of the epidermis

of the ungual crest

This improved technique for feline laser onychectomy allows the laser

surgeon to eﬀectively dissect the third phalanx from the digit with a minimal
amount of trauma to the patient [2]. Postoperatively, the preserved redun-
dant epidermis of the ungual crest acts as a biologic bandage to cover the
onychectomy site. All laser surgical dissection is accomplished from a dorsal
approach. Most of the dissection is directed at the connective tissue struc-
tures of PIII and avoids the highly vascular soft tissue surrounding the claw.
When performed correctly, the technique eliminates the need for tourni-
quets, bandages, and wound closure. Postoperative pain and swelling are
also minimized.

Patient preparation and anesthesia

Feline laser onychectomy patients are premedicated and anesthetized

according to the preference of the surgeon. All laser onychectomy patients
should be given an anesthetic protocol that includes pain management.
Although laser surgery inherently reduces postoperative pain, it is the obli-
gation of the veterinarian to provide an anesthetic protocol, including pain
management, suﬃcient for any elective surgical procedure that produces
moderate levels of pain.

Standard aseptic preparation is mandatory for all surgical procedures,

including laser onychectomy. All safety precautions, including use of protec-
tive eyewear, smoke-evacuating equipment, and use of laser safe facemasks,
must be observed when performing this and any laser surgical procedure.

Resection of the redundant epithelium of the ungual crest

The CO

laser (Luxar Laser, Model LX-20LP, AccuVet

, Lumenis, Inc.,

Santa Clara, CA) is set at 6 W in the continuous wave (CW) mode. For this
description, a 0.8-mm tip/beam diameter is used. Considering laser–tissue

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W.P. Young / Vet Clin Small Anim 32 (2002) 601–619

interaction, it is also possible to use a smaller diameter tip/beam size that
would increase the power density and potentially decrease the laser power
parameter (watts) needed. A curved mosquito forceps is placed on the claw
for manipulation. The ﬁrst step of this procedure involves two circumferen-
tial incisions in the redundant epidermis of the ungual crest. The ﬁrst incision
is at the most distal edge of the redundant epithelium. A 360

° incision is per-

formed (Fig. 1). This incision releases the redundant epithelium from its most
distal attachment and allows it to be pushed proximally over the ungual crest.
A second 360

° circumferential incision is made 2 to 3 mm proximal to the ﬁrst

incision. The second incision allows the slightly deeper subcutaneous fascia
to be pushed proximally over the ungual crest as well (Fig. 2). The redun-
dant epithelium must be preserved during this phase of the procedure. Care
must be taken to keep it pushed proximally over the ungual crest at all times
for the duration of the onychectomy. Compromising the redundant epider-
mis will reduce its eﬀectiveness to cover the surgical site postoperatively.

Incision of the extensor tendon and synovium of the third phalanx

Proximal distraction of the redundant epithelium and subcutaneous fas-

cia over the ungual crest reveals the extensor tendon with its insertion on
PIII. The tendon is then incised at its insertion on the distal phalanx from
a dorsal orientation in a palmar direction (Fig. 3). Gentle traction will begin
to disarticulate the joint (PII-PIII). The synovium of PII-PIII lies just under
the extensor tendon. By extending the incision deeper in the same plane, the
synovium can be incised as well. Gentle traction of the mosquito forceps in a

Fig. 1. First 360

° circumferential incision in the redundant epithelium of the ungual crest.

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W.P. Young / Vet Clin Small Anim 32 (2002) 601–619

palmar direction will help facilitate the incision into and through the syno-
vial layer (Fig. 4). With experience, the laser surgeon can perform these two
steps with one extended incision. It is, however, important to understand
that the surgeon is cutting through two distinct structures of anatomy: the

Fig. 3. Incision of the digital extensor tendon.

Fig. 2. Second 360

° circumferential incision in the redundant epithelium of the ungual crest.

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W.P. Young / Vet Clin Small Anim 32 (2002) 601–619

extensor tendon and the synovium. Although the author has not experi-
enced postoperative complications with respect to damage or laser impact
to the condyles of PII, it is wise to keep the laser beam close to the distal
phalanx and to avoid collateral damage to the condyles of PII.

Ablation of the collateral ligaments of PII-PIII

Palmar distraction of the PII-PIII joint after incising the extensor tendon

and synovium will reveal the collateral ligaments. The collateral ligaments
are ablated in a ‘‘head-on’’ fashion with the laser beam aimed perpendicular
to the body of the ligament from a dorsal origin (Fig. 5). Again, gentle
traction in a palmar direction will help expose the ligaments for incisional
ablation. Care must be exercised at this point in the procedure. Do not ex-
cessively ablate tissue on the medial or lateral aspects of the surgery site.
Damage to the redundant epidermal tissue that lies adjacent and proximal
to the collateral ligaments will result in less coverage of the onychectomy
site. Once the collateral ligaments have been incised, gentle traction in a
palmar direction will disarticulate the joint.

Incision of the digital ﬂexor tendon and dissection of the subcutaneous
tissue of the pad from PIII

With continued traction in a palmar direction, the ﬂexor tendon is

exposed with its insertion on the ﬂexor process on PIII. Recognition of the
correct anatomic structures is vital at this point in the procedure. The laser
surgeon will view the digital ﬂexor tendon from a dorsal perspective. This

Fig. 4. Incision of the synovium of PII-PIII. The condyle of PII is visible.

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orientation is unusual in that the palmar surface of PIII is exposed because
of the extreme palmar rotation and distraction achieved by dissecting the
connective tissue structures of the joint. The laser beam is again directed
from a dorsal origin in a palmar direction. The ﬂexor tendon is vaporized
from its insertion on PIII (Fig. 6). Extreme palmar rotation and distraction
of the distal phalanx reveals the attachments of the subcutaneous tissue to
PIII (Fig. 7). These attachments are also incised with the laser. It is impor-
tant to keep the laser beam close to PIII when performing these last two
steps. Allowing the laser beam to drift away from PIII may cause damage
to the digital pad. The goal is to dissect the claw away from the digit and
to minimize trauma to the surrounding tissue (Fig. 8).

Postoperative care

At the end of the procedure, the laser surgeon should inspect each digit

for bleeding and excessive carbonization. Large amounts of char should
be carefully removed with a sterile surgical sponge. Usually, there is little
or no hemorrhage. Increased bleeding can be associated with too much trac-
tion placed on PIII during surgery. This results in tissue that is torn, rather
than vaporized. Occasionally, digits seem to hemorrhage for no apparent
reason, other than the fact the CO

laser does not control bleeding as readily

as other laser near-infrared wavelengths. The laser surgeon should not be dis-
couraged, however, because this happens infrequently. A temporary bandage

Fig. 5. Ablation of the medial collateral ligament of PII-PIII; redundant epithelium is pushed
cranial to the surgical site. Note that this photograph illustrates ablation of the medial collateral
ligament of digit I. The procedure is similar for all digits.

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W.P. Young / Vet Clin Small Anim 32 (2002) 601–619

Fig. 7. Extreme palmar rotation and distraction of PIII after the ﬂexor tendon is incised.

Fig. 6. Vaporization of the ﬂexor tendon.

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W.P. Young / Vet Clin Small Anim 32 (2002) 601–619

will alleviate the bleeding. Appropriate and rational antibiotic therapy is at
the surgeon’s discretion.

Postoperatively, the redundant epidermis will begin to cover the surgical

site (Figs. 9, 10). Slight swelling will occur in the epithelium. This swelling is
beneﬁcial, because it will push the redundant epidermis back to its original
anatomic position, covering the declaw site. Twenty-four hours postopera-
tively, the laser incisions will be diﬃcult to discern. When using this tech-
nique, there should be no need for wound closure.

Although some laser surgeons prefer to use tissue adhesives or small di-

ameter suture material to close wounds after a laser onychectomy proce-
dure, using this improved technique precludes closure because the
onychectomy incision is so small. In fact, tissue glue or suture material may
create a nidus of inﬂammation in already compromised tissues. This inﬂam-
mation may increase swelling, cause excessive grooming, and lead to inci-
sional infection. Finally, some veterinarians may prefer to routinely
bandage the feet for a short period to protect the digits from self-trauma.
Regardless of the technique used, however, it is essential the novice laser
surgeon feel comfortable with the procedure, which may mean practicing
on cadaveric specimens before clinical application.

Despite the great reduction in pain achieved by laser surgery, postopera-

tive pain management is essential. Rough recoveries associated with popular
short-acting induction agents, such as ketamine and diazepam, are inade-
quate for laser onychectomies. Despite the best of skills by the laser surgeon,
a patient who experiences a rough recovery exhibited by paddling in a cage

Fig. 8. Dissected PIII after laser onychectomy.

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Fig. 10. Redundant epithelium covering onychectomy site. Note the minimal size of the sur-
gical onychectomy site.

Fig. 9. Redundant epithelium covering surgical site.

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W.P. Young / Vet Clin Small Anim 32 (2002) 601–619

is likely to traumatize the surgical sites and cause them to hemorrhage.
Sedation and pain control are the keys to smooth recoveries and successful
laser onychectomies.

Canine laser castration

Canine castration is an elective procedure that lends itself well to the

adaptation of the CO

surgical laser. Because of the inherent characteristics

of the laser, the author and many other laser surgeons have obtained excel-
lent results. Postoperative pain and swelling, especially in large dogs, is mini-
mized by using the CO

laser.

Patient preparation and anesthesia

Few diﬀerences exist in the patient preparation and anesthetic protocols

of conventional and laser castrations. In fact, with slight variations, the
technique is a simple substitution of the laser beam for the stainless steel
scalpel. Both procedures require adequate surgical anesthesia and post-
operative pain management. Aseptic laser safe surgical preparation and
technique is essential, however. The patient is prepped and draped in dorsal
recumbency.

Technique

This technique generally follows the conventional surgical technique for

closed castrations taught by veterinary teaching hospitals worldwide. The
laser (Luxar Laser, Model LX-20LP, AccuVet

) is set at 6 W and in

CW mode. An appropriate prescrotal incision is made in accordance with
the size of the patient. This incision is accomplished by cranially advancing
a testicle to the prescrotal midline and incising the dermis until the testicle is
visible in the subcutaneous tissues (Fig. 11). Continual cranial pressure on
the testicle and suﬃcient enlargement of the incision in the dermis and sub-
cutaneous tissue allow the testicle to be extruded from the scrotum (Fig. 12).
Once the testicle has been extruded from the scrotum, the laser surgeon must
incise the connective tissue holding it in place. The testicle is held in place by
the spermatic fascia and the ligament of the tail of the epididymis [1]. These
attachments must be vaporized with the laser beam to mobilize the testicle
for ligation and removal. Gentle traction to the testicle exposes the sper-
matic fascia and scrotal ligaments (Fig. 13). These structures are manually
broken down in conventional castration techniques. In canine laser castra-
tion, these attachments are vaporized to avoid torn and bleeding blood ves-
sels (Figs. 14, 15). The blood vessels in the spermatic fascia and scrotal
ligaments are photothermally sealed on exposure to the laser beam during
dissection of the testicle. This procedure ensures that no hemorrhage occurs
postoperatively and that pain and swelling are minimized.

The absence of hemorrhage is the distinct advantage that laser castrations

have over conventional surgery. Care must be taken to avoid excessive trac-

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W.P. Young / Vet Clin Small Anim 32 (2002) 601–619

Fig. 12. Testicle extruded from a prescrotal incision.

Fig. 11. Midline prescrotal incision over cranially advanced testicle.

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Fig. 13. Exposure of the scrotal ligament and spermatic fascia.

Fig. 14. Vaporization of the scrotal ligament and spermatic fascia.

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W.P. Young / Vet Clin Small Anim 32 (2002) 601–619

tion on the spermatic fascia and scrotal ligaments. If excessive traction is
placed on these structures, they will tear and bleed, reducing the beneﬁts
of laser surgery. Additionally, care should be exercised to avoid penetrating
the parietal vaginal tunic to ensure that the described technique remains
‘‘closed.’’

Once the testicle is freed from its connective tissue attachments in the

scrotum, appropriate-sized ligatures are implemented for ligation of the
spermatic cord. A three-clamp technique is usually used. Circumferential
or transﬁxed ligatures are used at the surgeon’s discretion. Amputation of the
spermatic cord may be achieved using the laser or scalpel. The technique is
then repeated for the second testicle through the initial incision in the dermis.

Surgical wound closure is standard. The author favors a two-layer closure

with a synthetic absorbable monoﬁlament suture, such as polydioxanone or
polyglyconate on a taper needle. The subcutaneous tissues are closed with
simple interrupted sutures, eliminating all ‘‘dead space’’ (Fig. 16). A contin-
uous horizontal subcuticular suture pattern is used to close the epidermis,
and the knot is buried in the subcutaneous tissue (Fig. 17). Skin sutures are
avoided to keep the patient from licking the surgical site and potentially
creating postoperative complications. Attention to detail is important during
this procedure, and by minimizing hemorrhage throughout the procedure, no
matter how small, there will be decreased postoperative pain and swelling,
which leads to the greater overall comfort of the patient. Appropriate and
rational antibiotic therapy is left to the surgeon’s discretion. Pain management

Fig. 15. Vaporization of the spermatic fascia. Care must be taken to avoid penetrating the
parietal vaginal tunic during this technique.

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Fig. 16. Elimination of dead space with simple interrupted subcutaneous sutures. No hemor-
rhage is observed in the surgical site.

Fig. 17. Subcuticular closure with a continuous horizontal suture pattern. The knot is buried in
the subcutaneous tissue.

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W.P. Young / Vet Clin Small Anim 32 (2002) 601–619

is encouraged, as with any surgical procedure that produces patient discom-
fort.

The CO

laser has also been reported as a useful tool to minimize hemor-

rhage and inﬂammation during the ‘‘open’’ castration technique in the dog.

Some laser surgeons have advocated a direct scrotal approach when using

the laser for canine orchidectomy. The beneﬁts of using the laser for a scro-
tal approach have been a reduction in inﬂammation and a decreased oper-
ating time for the procedure. Tissue adhesives are used to close the scrotal
incisions. With potential complications, such as increased licking of the sur-
gical site, reaction to the tissue glue, and possible postoperative infections,
the author prefers the more conventional prescrotal approach.

Elective laser mass removal and ‘‘lumpectomies’’

The CO

surgical laser can be used extensively for simple ablation or re-

moval of masses from the integument and oral cavity. To use laser technol-
ogy for excision of potential neoplasms, however, it is essential that the
laser surgeon follow appropriate surgical oncologic principles [2]. Although
clinical experience is invaluable, one must recognize that the laser is just a
tool for more precise removal of pathologic tissue while providing better con-
trol of bleeding, inﬂammation, and pain.

Technique

Generally, most known benign lesions, such as adenomas or papillomas

(1 cm in diameter or less in size), can easily be removed using ablation and/
or simple excision (Figs. 18, 19). These lesions can be removed in some
cooperative patients with local anesthesia, without the risk associated with
general anesthesia. The tissue to be removed is clipped and prepared for sur-
gery using aseptic protocol with nonﬂammable agents. Inﬁltration of the
lesion with a local anesthetic, such as 2% lidocaine, is usually suﬃcient.
Mass ablation using vaporization is achieved by exposure to the laser (Luxar
Laser, Model LX-20LP, AccuVet

) beam with the appropriate power set-

ting, starting at approximately 6 W in CW mode for small dermal masses.
The mass is ablated sequentially in layers. Char is wiped away with a sterile
surgical sponge to not only reduce thermal injury to the surrounding tissues,
but also to visualize the progression of vaporization. The lesion will usually
have a diﬀerent texture and appearance when compared with the normal
dermis and subcutaneous tissue of the patient. Small areas of laser ablation
or simple excision may be allowed to heal without closure. Again, suspected
neoplastic masses should never be removed in this fashion; proper oncologic
procedures must be followed, including preoperative diagnosis using appro-
priate biopsy procedures. Microscopic inﬁltration into the surrounding tis-
sue is impossible to detect. Wide excision of suspected neoplastic masses is a
necessity for the safety of the patient.

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W.P. Young / Vet Clin Small Anim 32 (2002) 601–619

Fig. 19. Adenoma in Fig. 18 removed by simple excision using a CO

laser.

Fig. 18. Small adenoma on ventral abdomen of a 13-year-old Labrador Retriever.

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W.P. Young / Vet Clin Small Anim 32 (2002) 601–619

Excision of larger masses follows conventional surgical and oncologic

techniques. The laser beam is used in the same role as that of a scalpel, creat-
ing an incision in the dermis and around the lesion to remove it (Fig. 20).

One must remember that all biologic tissue will be damaged after expo-

sure to the laser beam, and consideration must be given to any vitally impor-
tant anatomic structures in the surgical ﬁeld. Larger masses and suspected
neoplasia often have increased blood supply and, consequently, larger blood
vessels supplying them. The CO

laser minimizes bleeding by vaporizing and

photothermally sealing small blood vessels (<0.5 mm in diameter). There-
fore, the beginning laser surgeon should not rely on the laser as a substitute
for good surgical technique. Larger vessels must be isolated and ligated to
prevent increased hemorrhage from occurring. Histopathology on all sus-
pect tissues is encouraged.

The economics of laser surgery for elective procedures

Veterinarians today have witnessed the most rapid expansion of science

and technology in human history. Computers, computed tomography scan-
ners, magnetic resonance imaging, and lasers are a few examples of the ever-
expanding technology. Veterinary medicine has evolved dramatically over
the last decade, and veterinarians have been challenged to keep pace with
the rapid advancement of science through the years. As our society em-
braces each new technologic achievement, veterinarians are inspired to adapt

Fig. 20. Suspected neoplastic mass given wide excision with the CO

laser. Appropriate surgical

excision using appropriate oncologic principles must be observed. Note the lack of hemorrhage.

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W.P. Young / Vet Clin Small Anim 32 (2002) 601–619

and evolve along with the expectations of society. This task is diﬃcult for
the veterinary practitioner. Adaptation of proven new technology quite
clearly aﬀords improved patient care. There can be little argument of this
fact. The costs associated with implementing new technology can be exten-
sive, however, and beyond the ﬁnancial resources of the veterinary practi-
tioner.

The dichotomy of patient care and economics has long been an issue in

the veterinary profession. Veterinary medicine is unique in this respect. It
is only recently that our human physician counterparts have experienced
this dichotomy in the form of managed care. In the veterinary profession,
most patient care is funded through the disposable income of their owners.
Few third-party insurance subsidies exist to ﬁnance the implementation of
new technology. New technology must have a positive impact on patient
care and be economically justiﬁed. Fortunately, as recent advancements in
science become more reﬁned, the costs of implementing them decrease and
make them more attractive to the veterinary profession.

The recent development of the surgical laser, speciﬁcally the CO

laser,

for veterinary medicine is a good example of new technology that can be
implemented in private practice. The criteria of improved patient care and
economic viability can be achieved with the CO

surgical laser. Increased

patient comfort is readily evident and very important to the veterinary prac-
titioner. Equally important is the economic viability of the CO

laser.

The economic viability of the CO

laser can be shown in two ways. First,

it can be a labor-saving device. It can reduce the surgical time required to
perform many diﬀerent types of surgery, such as dermal mass removal, oral
surgery, feline onychectomy, and canine neuters. A reduction of surgical
time also decreases anesthetic-related costs. Additionally, the reduction of
postoperative pain and swelling lead to fewer postsurgical complications,
further decreasing labor costs.

An illustration of the labor-saving features of the CO

laser can be found in

the feline laser onychectomy. With proﬁciency, a laser onychectomy can be
performed in 15 to 20 minutes. There is no closure. Patients rarely exhibit
postoperative hemorrhage and therefore do not require bandaging. Although
the laser onychectomy patient is hospitalized overnight, they require only
good observation. Again, there are no bandages to remove from painful and
angry patients the morning after surgery. The author has experienced a near-
zero postoperative complication rate. Infections and lameness associated with
conventional dewclaws are virtually eliminated by using the CO

laser. This

beneﬁt further decreases labor costs and additional aggravation for the sur-
geon and staﬀ. Canine laser neuters are also a good example of a procedure
that saves labor because of the very low rates of postoperative complications.
Hemorrhage is eliminated in canine laser neuters, even in large dogs. Patients
with painful surgical sites and swollen scrotums are rare.

The second economic impact that the CO

laser has is its ability to increase

surgical fees, even for elective surgical procedures. Procedures performed

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W.P. Young / Vet Clin Small Anim 32 (2002) 601–619

with a laser usually command an increase of 35% to 50% over conventional
surgical fees. Owners are generally pleased with the implementation of laser
technology and are accepting of the fees required to provide it. The practi-
tioner need only calculate the number of procedures their respective practice
performs to decide if the purchase of a laser can be economically justiﬁed. To
further enhance the potential of increased revenues from the laser, the practi-
tioner can dictate the methodology of elective surgery to the CO

laser. This

beneﬁt usually occurs when the surgeon becomes proﬁcient with the laser and
is convinced of its superior performance. Many veterinary hospitals incor-
porating CO

lasers into their surgical practice cease to provide conventional

surgery for selected elective surgeries because of the advantages of laser tech-
nology. Very few established clients will elect to take their pets to unfamiliar
facilities based on the surgeon’s genuine dedication to laser surgery.

Laser surgery is gaining wide acceptance as our society becomes more

technologically advanced. The reliable results obtained from laser surgery,
coupled with its economic viability, make the CO

laser an attractive addi-

tion for the veterinary practitioner to implement for elective as well as non-
elective surgical procedures.

References

[1] Evans HE, de Lahunta A. In: Miller’s guide to the dissection of the dog, 2nd edition.

Philadelphia: WB Saunders; 1980. pp. 159–60.

[2] Young WP. A new technique for feline carbon dioxide laser onychectomy by resection of the

redundant epidermis of the ungual crest. In: Lasers in surgery: advanced characterization,
therapeutics, and systems X. Proceedings of International Society for Optical Engineering,
3907, Lasers and biophotonics in veterinary medicine. San Diego (CA): 2000. p. 484–90.

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Use of the carbon dioxide laser

for perianal and rectal surgery

Bert A. Shelley, DVM, MS

Bradford Park Veterinary Hospital, 1255 E. Independence, Springﬁeld, MO 65804, USA

Many disorders of the body are amendable to laser treatment, and many

of these problems have speciﬁc needs that would require a laser of diﬀerent
wavelengths. Unfortunately, no ideal or all-purpose laser exists for all con-
ditions of the body. An all-purpose laser would be tunable with operator-
deﬁned wavelengths from the infrared to ultraviolet spectrum of light, it
would have a wide range of power, be portable, and it would exhibit eco-
nomic and reliable performance [1]. Because there is no laser with all these
capabilities, a laser has to be chosen to treat the speciﬁc needs of each
patient. The light emitted from a carbon dioxide laser has a wavelength of
10,600 nm, which is in the far-infrared light spectrum [1–3]. This wavelength
of light is highly absorbed by water, creating a thermal eﬀect [1–3]. Because
all soft tissues in the body are composed mainly of water, the carbon dioxide
laser penetrates very shallow into tissue, and there is very little collateral
thermal damage. This interaction makes the carbon dioxide laser a useful
tool for incising, excising, and photoablating soft tissue and allows for ﬁne,
controlled dissection of tissue. The axiom of ‘‘what you see is what you get’’
applies to the properties of the carbon dioxide laser [1,2]. Finally, the carbon
dioxide laser seems to have a lower learning curve when compared with
other types of lasers. It is for these reasons that the carbon dioxide laser
is a very useful tool for treating conditions of the perianal region.

Advantages of using the carbon dioxide laser in perianal surgery include

less bleeding, less pain, less swelling and decreased infection. The carbon
dioxide laser can cut and coagulate blood vessels up to approximately 0.5
mm in diameter. This precision is enough to control most hemorrhages of the
perianal region. Larger vessels may have to be cauterized or ligated. As the
laser cuts, it seals nerve endings and axons, which decreases the postoperative
pain experienced by most patients. Because the laser also seals lymphatic

Vet Clin Small Anim 32 (2002) 621–637

E-mail address: aashelbert@aol.com (B.A. Shelley).

0195-5616/02/$ - see front matter

PII: S 0 1 9 5 - 5 6 1 6 ( 0 2 ) 0 0 0 0 8 - 6

vessels, there is less ﬂuid extravasated into the tissue, which leads to less post-
operative swelling. Because bacteria are mainly composed of water, as are
most cells, the energy from the carbon dioxide laser will cause a photothermal
eﬀect and kill the bacteria. Because the perianal region is a contaminated area,
the laser will help decrease bacterial counts and may decrease the risk of a
postoperative infection. Together, these advantages will help patients return
to function quicker and with less postoperative complications [1–4].

Common uses of the carbon dioxide laser in perianal surgery include exci-

sion of perianal tumors, rectal tumors, anal sacculectomies, and treating peri-
anal ﬁstulas. The carbon dioxide laser can also be used to assist in the
approach to the dorsal aspect of the rectum or the approach to repair perineal
hernias. The carbon dioxide laser is another incising and ablating tool that
can help make these tasks easier for the surgeon and better for the patients.

Surgical anatomy of the perianal region

The following text is a basic anatomical description of the rectum, anus,

and perianal region. The reader is referred to an anatomy text for a more
detailed description of this area.

The rectum is the segment of the large intestine that courses through the

pelvic canal and ends at the anus. It is innervated by autonomic nerve ﬁbers
from the pelvic plexus. The pelvic plexus is composed of paired parasym-
pathetic pelvic and sympathetic hypogastric nerves. The terminal part of the
rectum is supported by the levator ani muscles medially and the coccygeus
muscles laterally. The external anal sphincter muscle demarcates the caudal
limit of the rectum. The rectum’s major blood supply is from the cranial
rectal artery, which is a branch of the caudal mesenteric artery. Lymphatics
drain cranially into the medial iliac lymph node [5–8].

The anal canal is continuous with the rectum to the anus. It is divided

into three zones: columnar, intermediate, and cutaneous zones. The inner-
most zone, the columnar, has a series of longitudinal mucosal and sub-
mucosal ridges called the anal sinuses. Anal glands are found in the
columnar and intermediate zones. Sebaceous, circumanal, and apocrine
sweat glands are found in the cutaneous zone. The anus is the external open-
ing of the anal canal [5–8].

Defecation is controlled by the internal and external anal sphincter mus-

cles. The internal anal sphincter muscle is a circular smooth muscle that lines
the anal canal. It is innervated by parasympathetic branches of the pelvic
nerve and functions to prevent indiscriminate defecation. The external anal
sphincter is a large circumferential band of skeletal muscle and is responsible
for fecal continence. It is innervated by the caudal rectal branches of the
pudendal nerve. This is a voluntary nerve supply. The blood supply is from
the perineal arteries [5–8].

The anal sacs are blind diverticula that are located on each side of the

anus. The sacs are lined with microscopic sebaceous and apocrine glands.

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B.A. Shelley / Vet Clin Small Anim 32 (2002) 621–637

The ducts of the anal sacs open in the cutaneous zone at approximately the
4 to 5 o’clock position for the right anal sac and the 7 to 8 o’clock position
for the left anal sac on each side of the anus. The anal sac openings on the
cat are more lateral to the anocutaneous line than on the dog. The anal sacs
lie between the internal and external anal sphincters [5–8].

Patient preparation

Preparation of the perianal region helps decrease the risk of a postopera-

tive problem. If rectal surgery is going to be performed, food needs to be
withheld for 24 hours before surgery. Enemas and laxatives can be used the
day before surgery to help evacuate the colon and rectum. Enemas should
not be used within a few hours of surgery, because they can liquefy fecal
contents and can cause contamination of the perianal region during surgery.
For perianal and rectal surgery, the rectum is manually evacuated, and the
anal sacs expressed after the induction of anesthesia [7]. Care must be taken
when clipping the perianal region because the skin is very thin and can be
easily irritated during the clipping process, which can lead to serious post-
operative discomfort, increased risk of infection, misery for the animal, and
anguish for the owner. Before surgery, a purse string suture or gauze sponge
needs to be placed in the rectum to prevent leaking of fecal material or
methane gas. The energy from the laser and heated carbon particles can
ignite the methane gas [2,3]. For surgery, the patient is placed in ventral
recumbency on the end of the surgical table with their rear limbs extended
over the end of the table or folded up under them. Care is taken to pad the
edge of the table to prevent injury to the rear limbs [7,8]. The tail can
be secured dorsally over the back with tape or a towel clamp and tape
(Fig. 1). The area is aseptically prepared for surgery.

Because the perianal region is very contaminated, the risk of infection is

high. Even though photothermal energy kills bacteria, the use of prophylac-
tic antimicrobials will help reduce the incidence of postoperative infections.
Antimicrobials used for prophylactic treatment before perianal surgery must
be eﬀective against gram-negative bacteria and anaerobes. Second- or third-
generation cephalosporins can be used, but can be very expensive. Combina-
tions of a ﬁrst-generation cephalosporin or ampicillin and an aminoglyco-
side can be eﬀective. They can also be combined with a ﬂuoroquinolone
for good prophylactic protection. Combinations with metronidazole are
useful when treating rectal lesions [7].

Basic considerations for laser surgery of the perianal region

Appropriate laser safety is essential for a successful surgical outcome in the

perianal region and for preventing injuries to the patient and surgical staﬀ.

Several manufacturers are currently marketing carbon dioxide lasers for

veterinary surgery. The procedures, tip sizes/beam diameters and power

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B.A. Shelley / Vet Clin Small Anim 32 (2002) 621–637

settings described in this article were performed using a 20-W carbon dioxide
laser (Novapulse, Luxar Corporation, Bothell, WA). For incising or excising
soft tissue of the perianal region, 6 to 12 W in a continuous or superpulsed
mode is usually suﬃcient to cut the tissue. Lower power settings are used
in areas where the skin is thin to allow for more precise control. Waveguide
tip sizes for incising or excising can range from 0.3 to 0.8 mm in diameter. The
smaller tip sizes also allow for more precise control of the laser beam and
increase the power density at the laser–tissue interface. For ablating tissue,
8 to 15 W in a continuous or pulsed mode (20 msec bursts, 20 cycles/s, and
40% of the power setting) may be used. Tip sizes from 0.8 to 1.4 mm in di-
ameter may be used. The laser beam can be ‘‘defocused’’ to ablate and coagu-
late larger volumes of tissue at higher power parameters. These settings and tip
sizes are intended as a guide. Each surgeon will learn what tip sizes and power
settings work best for them as they gain experience with this laser.

When incising, excising, or ablating tissue, it is critical to wipe away the

char (carbonized tissue) that accumulates in the wound with a saline-soaked
gauze sponge. Char can act as a ‘‘heat sink’’ and cause collateral thermal
necrosis to surrounding tissue. It can also act as a foreign body in the wound
and inhibit wound healing. Excessive amounts of char can also lead to
wound dehiscence [2,3].

Wound closure methods vary depending on surgeon’s preference. Typi-

cally the subcutaneous tissues are closed with a 3-0 to 4-0 monoﬁlament
absorbable suture material, such as poliglecaprone 25, polydioxanone, or
polyglyconate, using a simple continuous or interrupted pattern. The skin

Fig. 1. Patient placed in ventral recumbency at the end of the surgical table with its tail secured
dorsally with a towel clamp and tape. The pelvis is elevated with towels, and the end of the table
is padded.

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B.A. Shelley / Vet Clin Small Anim 32 (2002) 621–637

can be closed with a monoﬁlament nonabsorbable suture material, such as
nylon or polypropylene, in a simple interrupted pattern or with an intra-
dermal suture pattern using one of the monoﬁlament absorbable suture.
Suture materials with swaged-on-needles are used to minimize tissue drag.

Perianal tumors

Perianal tumors (circumanal, hepatoid tumors) are very common in the

male dog and rare in the female dog or cat. Most perianal tumors in the
male dog are benign. Perianal adenomas comprise more than 80% of all
perianal tumors and are the third most common tumor in the male dog.
They are commonly seen in older, intact male dogs. Most adenomas are hor-
mone dependent and will regress in size after castration. These tumors may
occur as solitary lesions (Fig. 2), or there may be multiple tumors (Fig. 3)
present in the perianal region. Perianal gland adenocarcinomas cannot be
grossly diﬀerentiated from adenomas. Because adenocarcinomas are not
hormonally responsive, castration will not be of any beneﬁt. They typically
are slow growing and slow to metastasize [7–10].

Anal sac carcinomas arise from the glands lining the anal sacs. Anal sac

carcinomas are more commonly seen in the female dog. These tumors are
typically solitary tumors associated with only one of the anal sacs. These
tumors can secrete a parathyroid hormone-like compound and can be asso-
ciated with a systemic hypercalcemia, polyuria, and polydipsia [7,8,10].

These tumors are easily diagnosed on physical examination. A thorough

rectal examination is necessary to help diﬀerentiate perianal gland tumors
from anal sac tumors. It is also crucial to determine if multiple tumors are

Fig. 2. A dog with a solitary perianal adenoma. A purse string suture has been placed in
the anus.

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B.A. Shelley / Vet Clin Small Anim 32 (2002) 621–637

present, so that adequate surgical planning can be performed. Cytology is not
very useful in diﬀerentiating perianal gland adenomas from adenocarcinomas
and can be useful for diﬀerentiating perianal gland tumors from other types of
skin tumors [10]. Anal sac carcinomas and mast cell tumors can be present and
will require wider surgical margins. Because these animals are typically older,
preoperative complete blood counts, serum chemistry proﬁles, and urinalysis
need to be performed to search for other systemic disease and to search for
problems that may be associated with the tumors (ie, hypercalcemia, which
can lead to renal dysfunction). Thoracic and abdominal radiographs may
be beneﬁcial for staging disease if a malignant process is suspected or if there
is a need for cardiopulmonary assessment before anesthesia [7,10].

Surgical excision is the preferred treatment for perianal tumors. Because

most tumors of the perianal region are adenomas, simple tumor excision and
castration is recommended. Perianal adenomas can be excised with minimal
margins. If a perianal adenocarcinoma is suspected, margins of at least 1
cm need to be resected. If extensive resection is required, up to one half of the
anal sphincter can be removed with some return of fecal continence [7,8,10].

For surgery, the patient is placed in ventral recumbency, and the tail is

secured over the back as previously described. The surgery site is aseptically
prepared. Using a CO

laser (Novapulse) setting of about 8 to 12 W in a

continuous or superpulse continuous mode and a tip size of 0.3 or 0.4 mm,
the tumor is excised with an elliptical incision. The power setting and tip
size/beam diameter are dependent on the type of carbon dioxide laser used
and the experience and comfort level of the surgeon. Start by using the laser
to outline an elliptical incision around the tumor (Fig. 4). This incision cre-
ates a guide for excising the tumor. When excising the tumor with a laser,
counter traction may be placed on either side of the incision and can distort
the area. After the outlining the margins of the incision, a full thickness

Fig. 3. A dog with multiple, ulcerated perianal adenomas.

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B.A. Shelley / Vet Clin Small Anim 32 (2002) 621–637

incision can be made around the tumor. Counter traction with ﬁngers or
thumb forceps is used to spread the incision apart to help determine when
the skin is incised. It may take several passes of the laser beam before a full
thickness skin incision is made. Again, it is important to wipe the char away
from the incision with a saline-moistened gauze sponge. Once the skin is
incised, the laser beam is used to dissect through the subcutaneous tissue
and ﬁnish excising the tumor (Fig. 5 ). Once the tumor is excised, the wound
is lavaged or wiped with a saline-moistened sponge to remove any char that
may have accumulated in the wound (Fig. 6). The subcutaneous tissue is
closed with a 3-0 or 4-0 synthetic monoﬁlament absorbable suture material
using a simple continuous or interrupted pattern. The skin is closed with
simple interrupted pattern with nonabsorbable suture material or an intra-
dermal pattern with an absorbable monoﬁlament suture material.

Prognosis for perianal adenomas is good. Perianal adenocarcinomas have

a guarded prognosis because local recurrence is common. Anal sac carcino-
mas have a poor prognosis because these tumors have a fairly high local recur-
rence rate and tend to metastasize to local lymph nodes [7–10].

Rectal tumors

The most common type of benign tumor in the rectum is an adenomatous

polyp [7,11]. Adenomatous polyps can be sessile, raised, or pedunculated.
They can occur as single or multiple tumors. Carcinomatous changes and car-
cinoma in situ can also occur [12]. Most polyps occur within 2 cm of the anal
opening. The most common presenting signs are tenesmus and blood in the
feces [7,11]. Most polyps can be palpated by rectal examination. Colonoscopy
is recommended to rule out disease more proximal in the rectum or colon.

Fig. 4. The carbon dioxide laser is used to outline the margins of an elliptical incision around a
perianal adenoma before full-thickness skin incision.

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B.A. Shelley / Vet Clin Small Anim 32 (2002) 621–637

Polyps can be treated by surgical excision, electrosurgery, or cryosurgery.

Laser excision of polyps helps to control hemorrhage during excision [7,11].
Because most polyps are within 2 cm of the anus, they can be approached by
rectal eversion (Fig. 7). For pedunculated polyps, the rectum is everted and
held with stay sutures to keep the rectum everted. The tumor is excised at the
base, using the carbon dioxide laser (Novapulse) set on CW mode with a 0.4
or 0.8 mm tip and 8- to 10-W power setting. If the base is small, laser excision

Fig. 5. The carbon dioxide laser is used to incise through the subcutaneous tissue deep to a
perianal adenoma. Note the lack of blood in the wound bed.

Fig. 6. A saline-moistened gauze sponge is used to gently wipe the char away from the wound
bed of an excised perianal adenoma.

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B.A. Shelley / Vet Clin Small Anim 32 (2002) 621–637

is suﬃcient, and suturing of the mucosa is unnecessary. The carbon dioxide
laser will control hemorrhage and will seal the wound. Large mucosal resec-
tions may require suturing with a monoﬁlament absorbable suture material.

Polyps with sessile bases can be managed with photoablation. Once the

rectum is everted and stabilized with stay sutures or with atraumatic tissue
forceps. The carbon dioxide laser (Novapulse) is used to ablate the tumor.
Using a 0.8 or 1.4 mm tip, a CW or pulse mode, and a power setting of
8 to 12 W, the tumor is ablated down to the level of the submucosa.
Mucosa can be sutured with an absorbable monoﬁlament suture material.
If sessile based tumors are very extensive, they can be treated by rectal
eversion with resection and anastomosis. Up to 4 inches of the rectum can
be everted without causing incontinence and perfusion problems [7]. The
rectum is everted and stabilized with through-and-through stay sutures
at the 12, 3, 6, and 9 o’clock positions. The rectum is excised using the
carbon dioxide laser; resecting 90

° or a quarter of the circumference at

a time. Each quarter section of rectum is sutured with 3-0 polydioxanone
or polyglyconate with a simple interrupted or simple continuous suture
pattern before continuing with the remainder of the rectal resection and
anastomosis. Tumors located more orally up the rectum may need to be
approached by a rectal pull through, ventral, or dorsal approach [7,8]. The
reader is referred to a surgical text for description of these procedures. The
carbon dioxide laser can be used to assist in performing these procedures
to help control hemorrhage.

Most adenomatous polyps can be controlled by excision. Adenomatous

polyps can recur or undergo malignant transformation. Carcinomas tend
to carry a guarded prognosis [7,8,11,12].

Fig. 7. Eversion of the rectum to expose a pedunculated adenomatous polyp.

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Laser-assisted anal sacculectomy

Anal sac problems are very common in the dog, but are rare in the cat.

Anal sac disease includes impaction, infection, abscess formation, and neo-
plasia. Most anal sac disease can be diagnosed by digital palpation. Many
dogs present with evidence of anal irritation, such as scooting, licking, and
biting at the anal area. Because the anal sacs may be swollen and inﬂamed,
the dog may avoid or disdain digital palpation. Abscessed or impacted anal
sacs can rupture and create a draining lesion. Anal sac carcinomas typically
occur in female dogs and can be associated with a paraneoplastic condition,
such as hypercalcemia [7–9,13].

The treatment options for anal sac disease include manual expression,

lavage of the sacs, administration of antibiotics, local infusion of an antibi-
otic/corticosteroid ointment, and dietary changes. Most problems can be
managed by medical therapy. Surgical excision of anal sacs is recommended
for recurrent sacculitis, tumors of the anal sacs, and as an adjunctive treat-
ment for perianal ﬁstulas. It is recommended that anal sacs that have been
abscessed should be removed. An abscessed anal sac should be treated medi-
cally until it is healed, and then both anal sacs should be removed. Most
problems of the anal sacs are unilateral; however, both sacs should be
removed at the same surgical procedure to prevent any future problems with
the contralateral anal sac [7,8].

The best time to perform surgery is when the anal sacculitis or an abscess

has been resolved. Surgery on an abscessed anal sac increases the risk of
leaving a segment of necrotic, friable anal sac in the wound. If any anal sac
tissue remains in the wound, it can lead to chronic draining tracts, which will
not heal until the remnant of anal sac tissue is removed. If the anal sac
abscess results in a chronic, nonhealing wound, surgery is indicated to
remove the diseased tissue.

Surgical removal of the anal sacs can be performed with a closed or open

technique [7,8]. For both the closed and open techniques, the animal is
placed in ventral recumbency with its tail secured dorsally over the back.
The pelvis can be elevated with pads or towels, being careful to pad the rear
limbs as they hang over the end of the surgical table. A purse string suture is
placed in the anus being careful not to interfere with the openings of the anal
sacs. The perineal area is prepared for surgery. For both the closed and open
techniques, a 0.3- or 0.4-mm tip can be used. The laser (Novapulse) is set
with a CW or superpulsed mode using 6 to 10 W. The lower power setting
is used in dogs with thinner perianal skin.

Closed technique

To begin, a surgical probe or small hemostat is placed down the opening of

the anal sac. Outward pressure will help identify the end of the blind sac.
Alternatively, wax or synthetic resin can be infused into the anal sac to

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distend the sac to aid in identiﬁcation. The laser is used to make vertical inci-
sions in the skin over the anal sac. The incision is continued until the end of the
anal sac can be identiﬁed. Once identiﬁed, the end of the sac can be grasped
with a thumb forceps, Allis tissue forceps, or a hemostat. The instrument is
used to apply counterpressure to aid in laser dissection. While grasping the
anal sac, the laser is used to dissect around the remainder of the anal sac. The
anal sac can be diﬀerentiated from the surrounding tissue by its gray color.
Dissecting closely to the sac prevents damage to surrounding structures, such
as the anal sphincter muscles and the caudal rectal artery. Dissection is con-
tinued until the duct is removed at the mucocutaneous junction. The duct is
ligated at this level using a 4-0 monoﬁlament absorbable suture material. If
the anal sac is inadvertently entered during dissection, all saccular tissue must
be removed, and the wound copiously must be lavaged with saline to remove
any contamination. The subcutaneous tissue is closed with a 4-0 monoﬁla-
ment absorbable suture material. The skin can be closed with a monoﬁlament
nonabsorbable suture material in a simple interrupted pattern or with an
intradermal suture pattern using an absorbable suture material [7,8].

Open technique

In the open technique, a grooved director or small hemostat is placed

down the opening of the anal sacs (Fig. 8). While applying outward pres-
sure, the laser is used to incise down through the skin and the external anal
sphincter to fully open the anal sac from the opening to the blind end of the
anal. Once the anal sac is opened, the lateral edge is grasped with thumb for-
ceps or Allis tissue forceps. Using the forceps to apply countertraction, the

Fig. 8. Anal sacculectomy being performed with a carbon dioxide laser. A hemostat is placed in
the anal sac, and the laser with a 0.4-mm tip/beam size is used to incise through the skin and
external anal sphincter to the level of the anal sac.

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laser is used to dissect the anal sac from the surrounding tissue. The entire
sac, duct, and oriﬁce are removed. The wound is copiously lavage with sa-
line, and the wound is closed as described with the closed technique. In the
open technique, care is taken to apply one to two sutures to pull the external
anal sphincter muscle back into apposition. Careful closure will help reduce
the risk of fecal incontinence [7,8].

Alternatively, the anal sac can be removed using a technique similar to

the open technique; however, in this case, the anal sac is not opened.
Instead, once the skin is incised down to the anal sac (Fig. 8), one arm of
a straight hemostat is placed down the opening and into the anal sac. The
anal sac is clamped (Fig. 9). This procedure allows the anal sac to be
manipulated as the anal sac is removed. Beginning at the anal sac opening,
the laser is used to dissect the stoma and neck of the anal sac. The hemostat
can then be rolled to apply countertraction as the laser is used to peel the
remainder of the anal sac from the surrounding tissue (Fig. 10). Closure is
performed using the procedures used for the open technique.

Postoperative complications, such as infection, incontinence, and chronic

draining tracts, can be minimized by careful surgical technique. The use of
the laser helps decrease the number of bacteria in the wound, which
decreases the postoperative infection rate. By dissecting as close to the anal
sac as possible during removal, one can prevent or minimize damage to the
external anal sphincter and the caudal rectal nerves.

Chronic draining tracts are usually the result of leaving a piece of the lin-

ing of the anal sac [7,8]. The carbon dioxide laser is a useful tool for explor-
ing chronic draining tracts from incomplete excision of the anal sacs. Begin
by making an elliptical incision around the opening of the draining tract.
The opening of the tract is dissected free of surrounding tissue until the end
of the tract is encountered. This location is usually where the remnant of the

Fig. 9. A hemostat is clamped across the anal sac to apply traction and to aid in dissection.

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anal sac tissue is found. By using the laser for the dissection procedure, the
tract is eliminated, and the wound can be closed primarily or left open to
heal by second intention.

The prognosis for anal sacculitis or infection is good with anal sacculect-

omy. Anal sac carcinoma tends to carry a guarded to poor prognosis, be-
cause it tends to metastasize or recur locally [7,8].

Perianal ﬁstulae

Perianal ﬁstulae are characterized by multiple, chronic, ulcerating sinuses

or ﬁstulous tracts involving the perianal region (Fig. 11). Fistulas are usually
accompanied by a purulent, malodorous discharge. Although this disease is
primarily seen in German Shepherd dogs, other breeds are also aﬀected. The
exact cause of ﬁstulation is not known; however, there are several theories as
to the cause. In breeds with low tail carriage and a broad base tail, poor ven-
tilation and accumulation of fecal material, moisture, and glandular secre-
tions seem to be predisposing factors. The constant soiling and moisture
may result in infection and inﬂammation of the perianal skin adnexa
[4,7,8]. The ﬁstula could also result from inﬂammation of the apocrine
glands, impaction and infection of the anal sinuses or crypts, infection of the
cercumanal glands or hair follicles, anal sac infection or abscesses, or a com-
bination of any of these conditions. Because autoimmune disease and
inﬂammatory bowel disease may be involved in the pathogenesis of the dis-
ease, some of these dogs will respond to anti-inﬂammatory and immunosup-
pressive drugs [7,8,13–15].

The medical treatment of the disease is to keep the perianal area clipped

and cleaned, to perform daily lavages of the sinuses and ﬁstulas with

Fig. 10. The hemostat is used to manipulate the anal sac, while the anal sac is excise with a carbon
dioxide laser.

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B.A. Shelley / Vet Clin Small Anim 32 (2002) 621–637

antiseptic solutions, and to administer systemic and/or topical antibiotics.
Some veterinarians will use an aluminum brace to elevate the tail to increase
ventilation [7,8]. Treatments with azathioprine/metronidazole, high-dose
prednisone coupled with dietary therapy, or the use of cyclosporine have
resolved or improved the disease in a high percentage of dogs with perianal
ﬁstulas [13–15]. Medical management of this disease usually fails because
owners typically get frustrated with the daily management or because the
treatment becomes cost prohibitive.

Surgical treatment is typically recommended [7,8]. Surgery can be done

alone or in combination with anti-inﬂammatory and immunosuppressive
agents [13]. The goal of surgery is to eliminate all necrotic or unhealthy
tissue (superﬁcially and in tracts of the ﬁstulas) and to stimulate second
intention wound healing [7]. The surgical procedures for treating perianal
ﬁstulas include superﬁcial or radical excision, cryosurgery, surgical debride-
ment using sharp dissection, chemical cauterization of diseased tissue, elec-
trosurgical fulgaration, and even high tail amputation (amputation at the
base of the tail) [7,8].

The carbon dioxide laser is an eﬀective tool for treating perianal ﬁstulas.

It is very valuable for excising and ablating necrotic or ulcerated tissue,
and it oﬀers the advantages of eﬃcient control of bleeding as the necrotic/
ulcerated tissue is removed. It also kills bacteria in the wound bed, thus
decreasing the bacterial counts and helping to prevent postoperative infection.
The laser also helps minimize postoperative discomfort in the patient [2,4].

The patient is placed on the end of the surgical table in ventral recum-

bency with its tail secured up and over the back. The perianal area is clipped
and prepped for aseptic surgery. Gauze sponges are placed in the rectum to
help prevent fecal spillage.

Fig. 11. A German Shepherd dog with a perianal ﬁstula.

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The carbon dioxide laser (Novapulse) is set to 8 to 12 W in a CW or super-

pulse mode. The ﬁstulas are probed to determine the depth and extent of the
necrotic tract. The anal sacs are removed if they are involved with the ﬁstulas.
Although they typically are not the primary cause of the ﬁstulas, they can be
secondarily involved by the disease process [8]. They can be removed by
either a closed or open technique (see earlier discussion on anal sacculect-
omy). The goal of laser surgery is to excise all necrotic skin or tissue and
to photofulgurate the wound bed to help stimulate second intention wound
healing. A 0.4- or 0.8-mm tip is used to excise any necrotic skin around the
ulcerated areas. Also, any undermined skin is removed. Next, the ﬁstulous
tracts are removed. The smaller tips or bean size can be used to excise any
deeper tracts. These tracts are excised to expose healthy tissue underneath.
Alternatively, a 0.8- or 1.4-mm tip can be used with a pulsed (20 msec
bursts, 20 cycles/s, and 40% of the power setting) or CW mode to treat the
wound bed and ﬁstulas. These areas are ablated or photofulgurated down to
the level of healthy tissue. The wound bed is ablated in layers until healthy
tissue is reached (Fig. 12). Char is wiped away with a saline-soaked gauze
sponge between layers. Wounds can be left open to heal by second intention
or they can be closed with a synthetic, monoﬁlament absorbable suture
material. Before closure, the wound is copious lavaged with isotonic saline.
Installation of a latex penrose drain (Ansell Perry, Massillon, OH) may also
be required if there is a large amount of ‘‘dead space’’ resulting from the pri-
mary closure technique.

Fig. 12. Using a 1.4-mm tip/beam size with a carbon dioxide laser, the bed of the ﬁstula is being
ablated down to healthy tissue. All ﬁstulous tracts were ablated.

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The laser oﬀers the advantage of less postoperative comfort. In a study

using neodymium:yttrium aluminum garnet (Nd:YAG) laser to treat per-
ianal ﬁstulas, it was documented by owners that their pets experienced less
postoperative discomfort. The laser was very eﬀective in controlling hemor-
rhage in the wound [4]. It also sterilizes or sanitizes by eliminating or reduc-
ing bacterial numbers in the wound bed. This advantage is very beneﬁcial,
because perianal ﬁstulas are often contaminated wound beds [2,3].

Postoperative care includes daily cleaning of the wound. Postoperative

antibiotics that are eﬀective against gram-negative bacteria may also be
used. Elizabethan collars, buckets, or side bars may be needed to prevent
licking and self-mutilation of the area. Stool softener can be used to help
prevent straining. The wound should be evaluated every 2 to 4 weeks to
assess healing (Fig. 13). The owner should be warned that it could take more
than one surgery to resolve or control the disease.

Postoperative complications, such as fecal incontinence, anal stricture,

and recurrence of the ﬁstulas, are more commonly present with severe disease.
Fecal incontinence can sometimes be controlled by diet. Z-plasty procedures
or excision of the stricture may be required if there is stool retention [7,8].

Conclusion

The carbon dioxide laser is a very eﬀective tool for treating diseases of the

perianal region. The skin of the perianal region is thin and sensitive. The
carbon dioxide laser oﬀers a ‘‘no touch’’ method of excising these lesions,
which helps decrease postoperative discomfort and irritation. The carbon
dioxide laser is very eﬀective in controlling hemorrhage from vessels smaller

Fig. 13. The same perianal ﬁstula as in Figs. 11 and 12. Two weeks after surgery. The ﬁstula is
approximately one fourth its original size.

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B.A. Shelley / Vet Clin Small Anim 32 (2002) 621–637

than 0.5 mm [1–3]. This is suﬃcient in controlling most hemorrhage caused
from the rich blood supply of the perianal region. The perianal region is
contaminated with bacteria. The carbon dioxide laser photothermally
vaporizes bacteria, so that bacterial numbers are decreased, which helps
reduce the risk of postoperative infections. These factors help the patient
recover quicker and return to function sooner.

References

[1] Crane SW. Surgical lasers. In: Slatter D, editor. Textbook of small animal surgery. 2nd

edition. Philadelphia: W.B. Saunders; 1993. p. 197–203.

[2] Bartels KE. Perspectives on the use of lasers in veterinary medicine. Stillwater (OK): De-

partment of Veterinary Clinical Sciences, Oklahoma State University.

[3] Nelson JS, Berns MW. Basic laser physics and tissue interactions. Irvine (CA): Beckman

Laser Institute and Medical Clinic, University of California, Irvine.

[4] Ellison GW, Bellah JR, Stubbs, et al. Treatment of perianal ﬁstulas with Nd:YAG laser-

results in twenty cases. Vet Surg 1995;24(2):140–7.

[5] Evans HE, Christensen GC. Miller’s anatomy of the dog, 2nd edition. Philadelphia: W.B.

Saunders; 1979. p. 486–92.

[6] Grandage J. Functional anatomy of the digestive system. In: Slatter D, editor. Textbook of

small animal surgery, 2nd edition. Philadelphia: W.B. Saunders; 1993. p. 483–502.

[7] Hedlund CS. Surgery of the perineum, rectum and anus. In: Small animal surgery. St.

Louis, MO: Mosby; 1997. p. 335–66.

[8] Matthiesen DT, Marretta SM. Disease of the anus and rectum. In: Slatter D, editor. Text-

book of small animal surgery, 2nd edition. Philadelphia: W.B. Saunders; 1993. p. 627–45.

[9] Henderson RA, Brewer WG. Oncology: skin and subcutis. In: Slatter D, editor. Textbook

of small animal surgery, 2nd edition. Philadelphia: W.B. Saunders; 1993. p. 2075–88.

[10] Withrow SJ. Perianal tumors. In: Withrow S, MacEwen E, editors. Small animal clinical

oncology, 2nd edition. Philadelphia: W.B. Saunders; 1996. p. 261–67.

[11] Straw RC. Tumors of the intestinal tract. In: Small animal clinical oncology, 2nd edition.

Philadelphia: W.B. Saunders; 1996. p. 252–61.

[12] Valerius KD, Powers BE, McPherron MA, et al. Adenomatous polyps and carcinoma in

situ of the canine colon and rectum: 34 cases (1982–1994). J Am Anim Hosp Ass 1997;
33(2):156–60.

[13] Tisdall PL, Hunt GB, Beck JA, et al. Management of perianal ﬁstulae in ﬁve dogs using

azothioprine and metronidazole prior to surgery. Aust Vet J 1999;77(6):374–8.

[14] Harkin KR, Walshw R, Mullaney TP. Association of perianal ﬁstula and colitis in the

German shepherd dog: response to high-dose prednisone and dietary therapy. J Am Anim
Hosp Ass 1996;32(6):515–20.

[15] Mathews KA, Sukhiani HR. Randomized controlled trial of cyclosporine for treatment of

perianal ﬁstulas in dogs. J Am Vet Med Ass 1997;211(10):1249–53.

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Diode laser and endoscopic laser surgery

Kenneth E. Sullins, DVM, MS

Marion duPont Equine Medical Center, Virginia-Maryland Regional College

of Veterinary Medicine, PO Box 1938, Leesburg, VA 20177, USA

Laser equipment

Diode lasers are replacing neodymium:yttrium aluminum garnet

(Nd:YAG) lasers in veterinary surgery, because they are smaller, more eﬃ-
cient, and more cost-eﬀective because of the semiconductor technology that
produces the laser (AOC LaserCare 50, 50-W, solid-state, 980-nm diode sur-
gical laser, Lumenis, Santa Clara, CA; Fig. 1) [1].

Although their applications are similar, commonly used medical diode

lasers operate at wavelengths of 810 or 980 nm versus the 1064 nm of Nd:YAG
lasers. Because these wavelengths are not in the visible spectrum, aiming
beams are used to show the operator where the laser energy will impact target
tissue. Diode lasers are commonly marketed in 25- to 60-W conﬁgurations.

Diode laser–tissue interaction

The wavelengths of the diode and Nd:YAG lasers penetrate comparative

depths into tissue because they are most absorbed by melanin, hemoglobin,
and darker pigments that do not usually occur on the surface. The concen-
tration of these or other darker pigments determines the penetration at a
given energy level. Nonpigmented tissue, such as cornea, absorbs none of
the energy, whereas a pigmented melanoma absorbs a great deal of the
energy. A caveat to this comes with the 980-nm diode laser, which has
increased water absorption compared with the 810-nm diode and the
1064-nm Nd:YAG laser, and produces an eﬃcient surface eﬀect (Fig. 2)
[2]. Subsurface, nonpigmented tissue, such as myelin, which may ordinarily
have been minimally aﬀected by these wavelengths, could be at higher risk
with the 980-nm diode laser. Tissue necrosis, hemorrhage, or neuropathy are
potential complications. Depth of penetration of the laser energy is a partic-
ular concern during endoscopic procedures of hollow organs.

Vet Clin Small Anim 32 (2002) 639–648

E-mail address: sullins@vt.edu (K.E. Sullins).

0195-5616/02/$ - see front matter

PII: S 0 1 9 5 - 5 6 1 6 ( 0 2 ) 0 0 0 1 3 - X

Laser delivery

Quartz ﬁber delivery allows function in the noncontact (delivery device

does not contact tissue) or contact mode. The tissue eﬀect is determined
by the wavelength and power density in the noncontact mode. The noncon-
tact mode is described by the pure deﬁnition of light interaction with tissue.
The purpose of the contact mode is to modify the raw interaction to achieve
a particular eﬀect. Laser ﬁbers usually arrive in sterile packaging or can be
sterilized using gaseous or cold sterilization techniques.

Fig. 1. Tabletop 50-W diode laser (980 nm). The unit operates from a standard electric outlet
and requires no external cooling source.

Fig. 2. Tissue absorption of common laser wavelengths. Note the relatively good absorption of
the diode and Nd:YAG wavelengths in hemoglobin and melanin. The 980-nm diode laser has
increased water absorption compared with the 810-nm diode and Nd:YAG lasers. (Modiﬁed
from illustration provided by Lumenis, Santa Clara, CA.)

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K.E. Sullins / Vet Clin Small Anim 32 (2002) 639–648

Fiber types

Noncontact or free-beam ﬁbers are squared, cleaved, or polished, so that

the coherent light is transmitted directly to the tissue (Fig. 3A). Depending
on the power density, these ﬁbers coagulate, vaporize, or ablate tissue. Power
density is determined by the ﬁber size and the energy delivered. Noncontact
ﬁbers are used for procedures, such as ablating masses, when underlying
tissue is of minimal concern. Tissue may also be coagulated in anticipation
of a later slough or to minimize hemorrhage for a subsequent incisive proce-
dure. To preserve optimal function, misshapen or crystallized tips must be
stripped of the plastic outer coating and cleaved. The quality of the tip can
be judged by the shape and clarity of the aiming beam.

Contact ﬁbers are sculpted or shaped to focus (or diﬀuse) the energy in

the desired manner (Fig. 3B). Hybrid shapes, such as a hemispheric ﬁber,
can accomplish some of both the contact and noncontact functions. The
most obvious contact function is incision of tissue where the desired eﬀect
is at the tissue surface.

Depth of the tissue eﬀect is controlled in the contact mode by the shape of

the ﬁber tip. Although the conical tip is the most commonly used contact

Fig. 3. Laser ﬁbers are shaped to produce the desired eﬀect. (A) This noncontact ﬁber has been
cleaved to deliver a coherent laser beam into tissue directly ahead of the ﬁber. The symmetric
circular spot size on the target indicates an even energy application. (B) Note the focus of the
aiming beam at the point of contact of this contact laser ﬁber. The laser energy will be
concentrated in the same location and will produce an incision in tissue.

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K.E. Sullins / Vet Clin Small Anim 32 (2002) 639–648

tip, others are also available. Care should be taken so that the shape of the
tip is maintained to preserve the desired eﬀect.

Fibers are shipped with some type of sculpted or functional end. Normal

use causes the tip to burn away. Laser energy applied when the tip is not
contacting tissue reduces the life of the tip, because the heat is not dissipated
into the tissue. Once the tip is lost, all ﬁbers become free-beam ﬁbers that
send a coherent laser beam directly from the ﬁber’s end. While cutting may
still be performed, a deeper than necessary tissue eﬀect is being exerted.
Although reshaping a contact ﬁber tip is possible, the operator becomes
responsible for its function. Another method of concentrating the laser
energy at the ﬁber–tissue interface is blackening the ﬁber tip with a dark
marker or charring it in tissue.

Fibers routinely come in 400 to 1000 lm diameters. The smaller the ﬁber

diameter, the more ﬂexible the ﬁber, and the greater the power density at the
target site (eﬃciency of tissue eﬀect for a given amount of laser energy). The
larger the ﬁber, the less ﬂexible, and the greater the area of tissue aﬀected per
discharge of energy. Larger diameter ﬁbers can transmit higher energies with
less risk of burning in two. Practically speaking, the most clinically useful
ﬁber diameters range from 600 to 1000 lm.

Delivery accessories

Laser ﬁbers usually must be guided or stabilized in some manner to

accomplish a procedure. A surface ablative procedure can be accomplished
by merely holding the ﬁber by hand. Incisive or deeper procedures, however,
require an instrument to manipulate the ﬁber. General surgical surface pro-
cedures can be accomplished using a handheld ﬁber holding ‘‘pencil’’ that
secures the ﬁber (Fig. 4).

Fig. 4. Devices that stabilize or direct laser ﬁbers for surgical procedures. (Top) Hand pencil for
general surgical procedures. (Middle) Rigid curved ﬁber guide for directing the ﬁber in deeper
tissue. (Bottom) Malleable ﬁber guide can be tailored to ﬁt diﬀerent situations.

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Diode laser safety

Eye safety

The diode wavelength requires safety glasses of optical density of at least

4.5 at 980 or 1064 nm; the same lenses serve for Nd:YAG and the diode
wavelengths. Although many diode laser surgical procedures are endo-
scopic, protective eyewear should still be worn in case a ﬁber breaks. Even
the aiming beams are harmful if they are directed at the eye.

Smoke evacuation

No laser smoke of any type should be inhaled. In addition to the health

hazards, it frequently causes headache and nausea. A powerful smoke evac-
uator should always be operated at the surgical site. For invasive pro-
cedures, suction can be applied at the nearest body opening and through
the endoscope biopsy channel, or the laser ﬁber can be introduced using a
suction handpiece as an insertion cannula.

Diode laser in general surgery

Noncontact laser surgery

The purpose of noncontact laser surgery is usually ablation or coagula-

tion of tissue. Ablation eﬀects are the ‘‘disappearance’’ of tissue into the
smoke evacuator and result from higher power for shorter periods. Coagu-
lation is characterized by a blanching of tissue and results from lower
powers for longer periods. Increasing distance to tissue, or reducing the
power, aﬀect coagulation versus ablation.

Noncontact surgery generally requires more power than contact surgery

because the energy must be transmitted across space and diﬀuses once tissue
is contacted. Noncontact procedures generally begin at 20 W, which compli-
cates procedures with smaller, less powerful machines. Although power den-
sities for a given laser power setting can be increased by using smaller ﬁbers,
the spot size of tissue eﬀect is smaller requiring patience to complete the pro-
cedure. In addition, continuous wave laser energy application at higher
powers may degrade and burn ﬁbers. This problem can be improved by
using an intermittent or repeat pulsed mode, which allows the ﬁber to cool
between energy pulses.

Contact laser surgery

Contact diode laser surgery is generally incisive. Any laser incision

requires tension so that the tissue separates as the incision is created. Energy
settings below 20 W are adequate for contact laser applications. Compress-
ing the lumen to occlude blood ﬂow with the laser ﬁber and applying power
low enough to coagulate rather than cut (<5 W) can coagulate small bleed-

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K.E. Sullins / Vet Clin Small Anim 32 (2002) 639–648

ing vessels. Flowing blood creates a heat sink that dissipates laser energy.
Vessels of approximately 2 mm or more in diameter should be ligated.

The ﬁber diameter of conical ﬁbers aﬀects its performance for incisive

surgery. Using a 600-lm ﬁber, the conical tip will degrade quickly; however,
the smaller diameter ﬁber maintains a power density that still allows ade-
quate contact cutting. If the laser procedure is close to vulnerable structures,
the tip should be carbonized or the ﬁber should be replaced to maintain
energy focus at the tip of the ﬁber. Using a 1000-lm ﬁber, the conical tip
is critical, because the power density will not be high enough to cut unless
the power is turned up signiﬁcantly as the tip degrades. The visible eﬀect will
diminish and require longer exposure to separate tissue; however, the deeper
eﬀect is continuing. A useful compromise between ﬁber diameter and power
density must be discovered for every situation. For bare ﬁber procedures,
such as endoscopically applied laser procedures, the stiﬀness of the 1000-lm
ﬁber may be preferable, whereas in other situations the ﬂexibility of the
smaller ﬁber may be needed.

Endoscopic laser surgery

Flexible or rigid endoscopically guided laser surgery is a main reason to

own a diode laser. Minimally invasive surgery reduces patient morbidity and
cost. Many formerly debilitating procedures requiring hospitalization have
been reduced to outpatient visits. Regardless of whether the goal of the pro-
cedure is palliative or curative, the quality of the patient’s life is preserved.

The procedure can be accomplished by inserting the laser directly

through the viewing device or by triangulation of a handheld laser ﬁber
or surgical instrument through an additional portal. The procedure is tai-
lored to ﬁt the situation, and the possibilities are endless.

Endoscope

Video systems and lasers should be ﬁltered to prevent interference with

the image on the monitor when the laser is activated. The laser and endo-
scope representatives should be consulted before purchasing complementary
units. When asepsis is necessary, cold sterilization is used with the endo-
scopic equipment. For ease of manipulation, the monitor of the videoendo-
scope should be placed adjacent to the patient, so that the image is the same
as if the operator was looking directly into the patient.

In a closed cavity, smoke can obscure vision and should be removed by

intermittent suction, or the laser cannula can be inserted through a hole in a
suction cannula where continuous positive pressure is not important. Smoke
may also collect on the lens and require lavage. Because spatter of hot tissue
can crack the lens of an endoscope, a respectable distance should be main-
tained between the patient and endoscope.

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K.E. Sullins / Vet Clin Small Anim 32 (2002) 639–648

Flexible endoscopic laser surgery

Generally, the smallest diameter endoscope available is the most desir-

able, because it reaches tighter spaces and is more ﬂexible. Very small endo-
scopes, however, usually sacriﬁce features, such as lavage capability or
four-way movement, which may compromise surgery. Laser ﬁbers are passed
through the biopsy channel of the ﬂexible endoscope to contact the target
tissue. The position of the biopsy channel in the ﬁeld of view impacts vision
during contact laser surgery. The most applicable position is ventral to the
ﬁeld of view, so that the ﬁber can contact tissue while being observed. The
next concern is the biopsy channel itself. Quartz ﬁbers may be sharp, or they
may break in the channel. Flexible polyethylene (PE) tubing of a diameter to
ﬁt the biopsy channel and transmit the particular laser ﬁber will help protect
the tissue from the sharp edges and will also protect the fresh conical tip on
the ﬁber as it passes through the angled insertion port of the biopsy channel.
The author has better results if the laser ﬁber is placed in the proximal few
inches of PE tubing, and both are inserted together. The proximal end of
the PE tubing should be ﬂame-ﬂared to keep it from disappearing down the
channel, and the distal end should be cut to stay ﬂush with the end of the
biopsy channel where it cannot be seen through the endoscope. Dual-
channel endoscopes allow simultaneous lavage or use of a grasping instru-
ment. The second channel requires a larger diameter endoscope, however,
and it makes the end less ﬂexible.

The ﬁber tip should be at least 1 cm into the visible ﬁeld before the laser is

activated. Heat adjacent to the endoscope will crack the lens, melt the lining of
the biopsy channel, or melt the PE tubing, which will cause either of the ﬁrst
two injuries. A 5-second delay before retracting the ﬁber into the channel
allows it to cool adequately. If the ﬁber tip has become crystallized from over-
heating, it is likely to break inside the channel. A break is better, however, than
losing the ﬁber tip in the patient. The broken tip can be expelled from the PE
tubing, outside the patient. Ablation using higher powers may place the ﬁber
at risk of burning within the endoscopic channel itself. The author has pre-
vented this by using the intermittent, pulsed mode on the laser to let the ﬁber
cool between pulses.

The technique of endoscopic noncontact laser surgery is straightforward.

The energy for ablation or coagulation is adjusted by visual eﬀect while pro-
tecting the endoscope. A vessel is coagulated by compressing its lumen with
the ﬁber tip and applying low power (<5 W). For contact surgery, the tech-
nique depends on the shape of the ﬁber tip. The most common sculpted
ﬁbers are conical or hemispheric. These tips must be drawn across tissue for
incision, because pushing them causes the tip to bury into tissue. Wedged
tips can be used in a ‘‘push’’ manner to incise tissue without burying.

One disadvantage when the tip is out of sight before withdrawing it

toward the endoscope is that the tip may either not be contacting tissue,
or it may be contacting some tissue other than the target. The ﬁber tip rather

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K.E. Sullins / Vet Clin Small Anim 32 (2002) 639–648

than the side of the ﬁber should be used for cutting to ensure the most eﬃ-
cient eﬀect. Manipulation of tissue with an instrument may optimize contact
between the ﬁber tip and the tissue. Depending on the location and physical
property of the tissue, a stiﬀer or more ﬂexible ﬁber may improve the result.
Incisions along the long axis of the endoscope require withdrawing into or
pushing the laser ﬁber from the endoscopic channel, whereas incisions
across the long axis of the endoscope (in any direction) accentuate move-
ment of the endoscope tip itself. The latter requires much more practice,
because both the motion of the endoscope and the contour of the tissue
must be accommodated. In addition, the motion must be appropriately
stopped to prevent the ﬁber tip from ‘‘ﬂipping’’ onto another tissue after
leaving the targeted surface. Rotation of the endoscope to allow ﬁber move-
ment along a diﬀerent tissue dimension may facilitate the procedure.

Rigid endoscopic laser surgery

Rigid endoscopes may access or explore some cavities better and through

smaller access portals than ﬂexible endoscopes. Rigid endoscopes commonly
used include arthroscopes or longer cystoscopes or laparoscopes. The laser
may be inserted through a channel in the endoscopic cannula parallel to the
scope, or it may be inserted through another portal in a triangulation fash-
ion. Some rigid cannulae have ﬁber deﬂectors to move the laser tip indepen-
dently from the endoscope. Where pressure is necessary, the ﬁber can be
inserted in a laser cannula through a stab incision without losing the seal,
whereas insertion through a laparoscopic cannula would cause a leak and
loss of inﬂation pressure.

Fig. 5. Brass hooks can be fashioned for tensing or elevating tissue for incision during endo-
scopic surgery. The size and tip can be tailored for any situation.

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K.E. Sullins / Vet Clin Small Anim 32 (2002) 639–648

Accessories

A few items facilitate endoscopic procedures. Contact laser surgery usually

requires some method of providing traction or tension on the tissue. If a
simple relieving incision is required, a brass hook can be fashioned to pro-
vide tension or to elevate the tissue above underlying structures (Fig. 5). Tis-
sue can be grasped for elevation or retrieval with a long forcep (Universal
Grasping Forceps, Richard Wolf Medical Institute, Chicago, IL; Fig. 6).
Debulking a larger mass may reduce the time and laser energy required to
ablate a mass. Electrosurgical loops can be used to amputate protruding
tissue, and the remaining base can be ablated with the laser (Acu Snare Poly-
pectomy Device ASJ-1, Wilson Cook Medical GI Endoscopy, Charlotte, NC;
Fig. 7). Baskets for retrieving resected tissue from body cavities eliminate the

Fig. 7. Larger masses can be debulked using an electrosurgical loop, so that the underlying base
of the mass can be ablated with the laser. Electrosurgical loop is passed through the biopsy
channel of an endoscope to encircle a pedunculated mass before amputation.

Fig. 6. Grasping forceps are used to elevate, tense, or retrieve excised tissue. (A) The 50-cm
instrument can be bent to ﬁt diﬀerent situations. (B) The jaws can be redirected by carefully
bending the shaft of the instrument. It is advisable to minimize bending.

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K.E. Sullins / Vet Clin Small Anim 32 (2002) 639–648

risk of dropping tissue or seeding cells or infection (Endocatch-II disposable
specimen pouch, US Surgical Corporation, Mansﬁeld, MA).

Conclusion

The diode laser is a useful addition to the surgical laser capabilities of a

veterinary practice. Even as CO

laser waveguides evolve, the diode ﬁber

will continue to be more universally applicable to endoscopic procedures. Its
tissue penetration properties aﬀect treatment of deeply situated lesions and
its portability is an advantage for surgeons who move from practice to prac-
tice. When these considerations are important and only one laser is aﬀord-
able, the diode unit becomes a strong consideration.

References

[1] Dorros G, Seeley D. Understanding lasers. In: Types of lasers. Mount Kisco (NY): Futura;

1991. p. 55–7.

[2] Auth DC. Fundamentals of lasers for endoscopy and laser tissue interactions. In: Jensen

DM, Brunetaud JM, editors. Medical laser endoscopy. Boston: Kluwer Academic Pub-
lishers; Dev Gastroenterol 1990;10:1–15.

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Lasers in ophthalmology

Margi A. Gilmour, DVM

Department of Veterinary Clinical Sciences, College of Veterinary Medicine,

Oklahoma State University, Stillwater, OK 74078, USA

The ﬁrst use of medical lasers in clinical practice was in ophthalmology.

The unique properties of the clear ocular media were ideal for laser light
transmission in the treatment of retinal disease. Since the 1960s, there has
been a steady development of new lasers in ophthalmology, and new
ophthalmic applications have been devised for existing lasers. This article
discusses the important characteristics of ocular tissues with respect to inter-
action with laser energy, the diﬀerent lasers used in ophthalmology and their
tissue applications, and ophthalmic conditions treated with lasers in both
humans and animals. Because the advancement of laser use in veterinary
ophthalmology is so closely linked with experimental and clinical uses for
humans, a familiarity with human applications is important for understand-
ing and advancing veterinary applications.

Characteristics of ocular tissue and ophthalmic lasers

Laser energy can be delivered to the ocular tissues in a variety of ways

using transscleral probes in a contact or noncontact mode, endoprobes for
use inside the eye, the laser indirect ophthalmoscope for transcorneal and
transpupillary transmission, the slit lamp biomicroscope, and an operating
microscope adapter. The eye is unique in that the various media absorb dif-
ferent and speciﬁc wavelengths of light—either preventing or promoting
transmission of the wavelength on to the next tissue or media. In general,
the cornea and sclera absorb very short ultraviolet wavelengths (200 to
315 nm) and long infrared wavelengths (1400 to 10,000 nm). The lens ab-
sorbs ultraviolet wavelengths of 315 to 400 nm [1]. Wavelengths in the blue,
blue-green, yellow, red, and near-infrared spectrum (400 to 1400 nm) pass
through the sclera and clear media and are absorbed by ocular pigments

Vet Clin Small Anim 32 (2002) 649–672

E-mail address: gmargi@okstate.edu (M.A. Gilmour).

0195-5616/02/$ - see front matter

PII: S 0 1 9 5 - 5 6 1 6 ( 0 2 ) 0 0 0 0 9 - 8

[1,2]. Shorter wavelengths (blue light) are absorbed better by the inner retinal
layers, creating surface puckering. Yellow light is selectively absorbed by
some red, subretinal neovascular membranes. Longer wavelengths (red
light) have deeper penetration to the subretinal vessels [3]. Wavelengths in
the infrared range penetrate the sclera well, and the longer the wavelength
the better the scleral transmission [4–6].

Three ocular pigments are responsible for absorption of laser energy:

melanin, hemoglobin, and xanthophyll [1,2,7]. Hemoglobin absorbs blue,
green, and yellow light well and red light poorly. Xanthophyll, located in the
macula, absorbs blue light [2,7]. Shorter wavelength (blue) lasers, therefore,
cannot be used to treat disease involving the macula. Melanin is the most
important pigment for laser energy absorption [7]. It eﬃciently absorbs visi-
ble and infrared wavelengths (400 to 1400 nm). Absorption increases as
wavelength decreases [2,4]. Because melanin is highly concentrated in the
uveal tissue and retinal pigmented epithelium (RPE), the choroid and the
RPE are the primary sites for laser energy absorption in the posterior seg-
ment of the eye. When laser energy is used for retinal photocoagulation,
heat is conducted from the RPE to the retina, causing permanent thermal
damage to the inner and outer photoreceptor segments. The mechanism
of the resulting therapeutic eﬀect is the destruction of target tissues in some
instances, such as choroidal neovascularization. In proliferative retinopathy
the mechanism is less well understood but may involve improved choroidal
oxygenation, the restoration of a new RPE barrier, and RPE production of
inhibitors of neovascularization [8,9].

The choice of an ophthalmic laser depends on target tissue absorption

characteristics and the desired type of tissue damage—thermal photocoagu-
lation, photodisruption, photoablation, or photochemical. Lasers can be
used in a continuous wave mode or pulsed mode, depending on the tissue
eﬀect desired. For example, the neodymium:yttrium aluminum garnet
(Nd:YAG) laser in a continuous wave mode has a thermal photocoagulation
eﬀect. When used in a pulsed mode, either Q-switching with nanosecond
pulses or mode-locking with picosecond pulses, the Nd:YAG has a photo-
disruptive eﬀect.

Commonly used ophthalmic lasers include the CO

, excimer, argon, tune-

able dye, Nd:YAG, and diode lasers (Table 1). The CO

laser has extraocu-

lar (eyelids and conjunctiva) ophthalmic applications. The CO

wavelength

has a primarily photoablative eﬀect [10] and is highly absorbed by water
rather than pigment. Water and tissue are vaporized within a very discrete
zone removing only a few cell layers at a time. The CO

wavelength is ab-

sorbed by the cornea and sclera. The excimer (‘‘excited dimer’’) laser has
a photoablative eﬀect. It is absorbed by the cornea and is capable of break-
ing intermolecular bonds and ablating tissue without causing thermal
damage to adjacent tissue [11], thus making it ideal for corneal remodeling.
The argon and dye lasers have a photocoagulation eﬀect. Energy is very
highly absorbed by melanin and is therefore used in direct applications to

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Table 1
Lasers used in human ophthalmology

Laser

Wavelength
(nm)

Color

Tissue
eﬀect

Ophthalmic
applications

Excimer

193

Ultraviolet Photoablation

Epithelial and

anterior stromal
keratopathies

PRK
LASIK

Argon

488–514

Blue-green

Photocoagulation Retinal

photocoagulation

514

Green

Iridotomy
Trabeculoplasty
Iridoplasty
Sclerostomy

Krypton

647

Red

Photocoagulation Retinal

photocoagulation

Diode

810

Infrared

Photocoagulation Cyclophoto-

coagulation

Retinal

photocoagulation

Iridotomy
Trabeculoplasty
Sclerostomy

Nd:YLF

1053 nm/psec

Infrared

Plasma-mediated

Intrastromal PRK

pulse duration

ablation

Sclerostomy
Iridotomy
Vitreous ﬂoater

ablation

Incision of epiretinal

membrane

Posterior capsulotomy
IOL polishing [29]

Nd:YAG

1064

Infrared

Capsulotomy

Continuous

wave

Photocoagulation Cyclophoto-

coagulation

Cataract surgery

Q-switched or

mode locked

Photodisruption

Retinal

photocoagulation

Iridotomy
Trabeculoplasty
Sclerostomy
Hyaloidotomy

Ho:YAG

2060

Infrared

Photoablation

Thermokeratoplasty
Sclerostomy

(continued on next page)

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M.A. Gilmour / Vet Clin Small Anim 32 (2002) 649–672

the retina, RPE, choroid, iris, and iridocorneal angle. The Nd:YAG laser
has a photocoagulation or photodisruption eﬀect, and the diode laser has
a photocoagulation eﬀect. Both are absorbed well by melanin and trans-
mitted well through the sclera and clear media allowing direct application
to the retina, RPE, choroid, and iris, or transscleral application to the ciliary
body and retina, RPE, and choroid. The shorter wavelength of the diode
(810 nm) versus the Nd:YAG (1064 nm) allows for better melanin absorp-
tion; however, the longer wavelength of the Nd:YAG has better scleral
transmission [5,6]. Scleral transmission by the diode laser can be increased
by using contact mode techniques [6,12]. The additional beneﬁts of the diode
laser are that it is small and portable, relatively inexpensive, runs oﬀ a stan-
dard electrical supply (110 to 120 AC), and requires low maintenance [13].
Table 1 lists the lasers used in ophthalmology, including laser wavelength,
tissue eﬀect, and applications.

Photodynamic therapy (PDT) uses a photosensitizing dye combined with

low-intensity laser light, speciﬁc for the absorption peak of the dye, to pro-
duce endothelial cell damage by release of oxygen-free radicals. The low
intensity light does not produce thermal damage, and the selective uptake
of the photosensitizing agent allows for damage to only the target tissue
[14,15]. The light sources that can be used for PDT include arc lamps, tun-
able dye lasers, and diode lasers [14]. The use of PDT in human ophthalmol-
ogy has focused on obliterating areas of abnormal neovascularization in the
choroid, and experimentally in the cornea using a topical porphyrin photo-
sensitizing agent and a 635-nm diode laser [14–16].

Table 1 (continued )

Laser

Wavelength
(nm)

Color

Tissue
eﬀect

Ophthalmic
applications

Er:YAG

2940

Infrared

Photoablation

Skin resurfacing
Trabecular ablation
Cataract surgery
Vitreoretinal

procedures

Sclerostomy
Capsulotomy

10,600

Infrared

Photoablation

Blepharoplasty
Skin resurfacing
Conjunctival

carcinoma
in situ [17]

Punctoplasty [17]

Abbreviations: Er:YAG

¼ erbium:yttrium aluminum garnet; Nd:YLF ¼ neodymium:yttrium

lithium ﬂuoride; Ho:YAG

¼ holmium:yttrium aluminum garnet; Nd:YAG ¼ neodymium:

yttrium aluminum garnet; PRK

¼ photorefractive keratectomy; LASIK ¼ laser in-situ keratomi-

leusis. IOL

¼ intraocular lens.

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Laser applications in human ophthalmology

Oculoplastics

The CO

laser is used for blepharoplasty, ablation of eyelid lesions, such

as seborrheic keratosis, chalazia, adnexal tumors, and lipid plaques (xanthe-
lasma), ablation of conjunctival papillomas or melanosis, and skin resurfac-
ing [17–19]. The CO

laser’s 0.1 mm depth of penetration allows precise

removal of eyelid lesions involving the medial canthus and puncta [17]. Its
use in blepharoplasty involves skin and conjunctival incisions and excision
or vaporization of fat [18,20]. Use of the CO

laser results in signiﬁcantly

less bleeding and postoperative swelling and ecchymosis; however, healing
takes longer because of sealing of blood vessels and heat necrosis [10]. Inter-
estingly, no diﬀerence is seen in the long-term results between CO

laser and

scalpel incisional blepharoplasty [19–21]. Both the CO

laser and the erbium:

yttrium aluminum garnet (Er:YAG) laser are used for periocular resurfacing
of wrinkles and blemishes [20,21]. Laser resurfacing is believed to have less
risk of scarring and dyspigmentation because of the greater control of
wound depth compared with dermabrasion and chemical peel [21]. Because
signiﬁcant thermal diﬀusion (and therefore thermal damage) will not occur
if the pulse duration is less than the time it takes the tissue to cool, the super-
pulsed and ultrapulsed CO

lasers were developed so that the pulses can cor-

respond to the thermal relaxation time of the skin [19]. In comparison, with
a wavelength of 2940 nm, the Er:YAG is absorbed by water more eﬀectively
than the CO

laser resulting in a tissue vaporization depth ten times shal-

lower than the CO

laser [19]. This light peeling eﬀect is associated with less

thermal damage, less pain, and faster healing and may be particularly
applicable for treating scars, mild wrinkles, and superﬁcial photodamage
[19,21].

Corneal surgery

The excimer laser has been the most commonly used laser for corneal

applications. Although this has primarily been refractive surgery, photother-
apeutic keratectomy with the excimer laser has been used for corneal disor-
ders involving the epithelium or anterior stroma, including recurrent erosion
syndrome, corneal dystrophies, keratopathies, scars, and pterygia [11,22]. Re-
fractive surgery for myopia, myopic astigmatism, and hyperopia has re-
ceived much publicity because of its popularity among the public and large
commercial interests. The excimer laser is capable of reshaping the cornea
by amounts of 0.5 lm with collateral damage of less than 1 lm [11,23]. The
ﬁrst technique described was photorefractive keratectomy (PRK) for myo-
pia, which uses the excimer laser to precisely ﬂatten the anterior corneal cur-
vature to decrease its refractive power. The corneal epithelium is removed
ﬁrst, either with the laser, manually or chemically, followed by laser ablation
of the underlying stoma [24]. Laser in-situ keratomileusis (LASIK) involves

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the use of a microkeratome to create a corneal ﬂap, hinged on one side, and
then the excimer laser is used to ablate the underlying stroma and the ﬂap is
replaced. Advantages of LASIK include less postoperative pain, less corneal
haze, and faster visual recovery. Disadvantages of LASIK include poor ﬂap
healing, deeper stromal ablation, and epithelial growth under the ﬂap [25].
Both PRK and LASIK have been eﬀective in treating low to moderate
degrees of myopia and astigmatism. Although neither procedure is as suc-
cessful for treatment of high myopia or hyperopia, LASIK may have a slight
advantage over PRK for both [26,27]. PRK for hyperopia requires reshap-
ing the peripheral cornea to create a steeper central corneal curvature. The
best results are in low hyperopia. Using large diameter corneal ablation,
LASIK for hyperopia tends to have less postoperative discomfort, faster
visual recovery, and better predictability for high-order hyperopia [27].

Other lasers that have been investigated for refractive surgery include the

neodymium:yttrium lithium ﬂuoride (Nd:YLF), Nd:YAG pumped optical
parametric oscillator laser, holium:yttrium aluminum garnet (Ho:YAG),
and a CW diode laser. The Nd:YLF laser is an ultrashort (40 psec) pulsed
laser with a wavelength of 1053 nm. Unlike the excimer laser, the Nd:YLF
laser removes tissue by plasma-mediated photodisruption [28]. The tissue
eﬀects with picosecond pulses are conﬁned to 20 to 50 lm, which minimizes
the thermal eﬀects to surrounding tissues [28,29]. Preliminary studies have
used the Nd:YLF laser to perform the keratectomy in LASIK [26,29] and
for intrastromal PRK. Correction of hyperopia using intrastromal PRK
uses a ring pattern of ablation in the peripheral cornea; correction of myopia
using intrastromal PRK uses a central spiral pattern of ablation [29]. Recent
studies have investigated the use of a Nd:YAG-pumped optical parametric
oscillator laser with a 2940 nm wavelength and nanosecond pulse rate for
corneal ablation equivalent to the excimer laser [23,30]. The Ho:YAG laser,
which operates in the infrared range at a wavelength of 2060 nm, uses ther-
mokeratoplasty for correction of hyperopia. A radial pattern is used to cre-
ate spots of precise stromal collagen shrinkage, while avoiding epithelial and
endothelial damage, creating a ﬂattening of the peripheral cornea, and steep-
ening of the central and paracentral cornea [31–33]. Recently a CW diode
laser with a wavelength of 1885 nm has been investigated for use in laser
thermokeratoplasty [32].

Glaucoma

Several laser techniques are used to treat primary open angle glaucoma

(POAG) and narrow-angle glaucomas.

Iridotomy

Laser iridotomy with the argon, Nd:YAG, or diode laser is used in

primary angle closure glaucoma, plateau iris, secondary pupillary block
glaucoma, malignant glaucoma, and before trabeculoplasty if pupillary

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M.A. Gilmour / Vet Clin Small Anim 32 (2002) 649–672

block is contributing to poor visualization of the trabecular meshwork
[34,35]. The argon laser has better coagulative eﬀects with decreased bleed-
ing; however, the Q-switched Nd:YAG laser, which causes photodisruption
of tissue independent of pigment, is more eﬃcient with better long-term
results [34–36].

Iridoplasty

Argon laser peripheral iridoplasty is used to open appositionally closed

angles by placing contraction burns of long duration, low power, and large
spot size along the extreme iris periphery to contract the iris stroma and pull
it away from the angle, thus mechanically opening the angle. Iridoplasty is
also useful before a trabeculoplasty procedure to facilitate visualization of
the trabecular meshwork [36–38].

Trabeculoplasty

Laser trabeculoplasty is used in POAG and pigmentary and pseudoexfo-

liation glaucomas [38] to decrease the resistance to aqueous outﬂow, even
though the precise mechanism of action is unknown [36,38]. Aqueous out-
ﬂow is blocked at the sites of trabeculoplasty, suggesting that there is an
increase in surface area to facilitate outﬂow in the nonlasered trabecular
meshwork. Studies also suggest that an increase in trabecular meshwork cell
division and turnover and/or increased production and turnover of extracel-
lular matrix proteins may decrease resistance to outﬂow [39]. The argon,
Nd:YAG, and diode lasers have been used for trabeculoplasty [36,39,40].
Treatment is directed at the junction of the pigmented and nonpigmented
trabecular meshwork to create a blanching of the tissue [38,39]. Selective
laser trabeculoplasty refers to the use of the Q-switched frequency-doubled
Nd:YAG laser (532 nm) to selectively target the pigmented trabecular mesh-
work cells without causing photocoagulative structural damage to sur-
rounding tissues. To date, results have been similar with all three lasers [39].

Trabecular ablation

Laser trabecular ablation, which creates multiple, microscopic openings

through the trabecular meshwork into Schlemm’s canal, has recently been
done with the Er:YAG laser with a 2940 nm wavelength for open-angle
glaucoma [41].

Hyaloidotomy

The Nd:YAG laser in pulsed mode has been used to rupture the anterior

hyaloid face for treatment of malignant glaucoma [34].

Sclerostomy

Laser sclerostomy can be performed by internal or external approaches.

Invasive internal approaches have used Nd:YAG, Ho:YAG, Er:YAG,
argon endolaser, and diode lasers [36,42]. Noninvasive internal sclerostomy

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using a gonioscopic lens to direct the laser energy has used the pulsed mode
Nd:YAG laser and various dye lasers [42]. Noninvasive external approaches
use the Ho:YAG laser, which uses a beam perpendicular to the sclera allow-
ing tunneling of the tip through a small conjunctival incision and placement
of the tip at the limbus to create a well-deﬁned canal [38]. The Er:YAG has
also been used experimentally because its wavelength (2940 nm) has better
scleral absorption than the Ho:YAG laser wavelength (2120 nm) [43]. Both
the pulsed Nd:YAG and the argon lasers have also been used to reopen
closed sclerostomies [44].

Cyclophotocoagulation

Transscleral cyclophotocoagulation with the Nd:YAG and diode lasers

has been used for refractory glaucomas, such as neovascular and posttrau-
matic glaucomas [36,45]. The recent development of microendoscopes has
enabled use of the diode laser in microendoscopic cyclophotocoagulation,
which allows direct visualization of the laser probe treating the ciliary pro-
cesses [46].

Capsulotomy

Since the 1980s, the Nd:YAG has been the laser of choice for posterior

capsulotomy; however, recently the Er:YAG laser has also been used [47].
The Nd:YAG, either Q-switched producing nanosecond pulses or mode-
locked using picosecond pulses, causes photodisruption of the opaciﬁed pos-
terior lens capsule in pseudophakic and aphakic eyes [17,48].

Cataract surgery

The use of lasers to remove cataracts is a relatively new area of laser

research. The Nd:YAG and Er:YAG lasers are currently under clinical
investigation for laser-assisted cataract surgery [49]. The direct Nd:YAG
system uses direct laser energy to fragment the lens. This is achieved by a
specialized tip that aspirates lens material into a 2.5-mm photofragmenta-
tion zone across which the laser energy travels to fragment the lens. The
indirect Nd:YAG system uses pulsed laser energy striking a titanium target
on the probe to produce optical breakdown and plasma formation. The
optical breakdown creates shock waves that make contact with the lens
material, which is held in apposition to the probe tip by aspiration. Once the
shock waves fragment the piece of lens, the fragmented material is aspirated
from the eye [49,50]. The Er:YAG laser wavelength is highly absorbed by
water. The Er:YAG system vaporizes the lens material, which is 63% water.
The phacovaporization occurs by explosive vaporization forming a cavita-
tion bubble and by micropulses traversing the cavitation bubble and gener-
ating energy just beyond it. The cavitation bubbles fragment the lens
material, which is then aspirated from the eye [49,51,52]. The proposed

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M.A. Gilmour / Vet Clin Small Anim 32 (2002) 649–672

advantages of laser-assisted cataract removal over ultrasonic phacoemulsiﬁ-
cation are smaller incision size, minimal heat generated, less bulky hand-
piece, and reduced risk of damage to the posterior capsule and corneal
endothelium. Disadvantages are decreased eﬀectiveness in lenses with a hard
nucleus, longer surgical time, limited ﬁber lifespan, and the expense of the
equipment [49,52].

Vitreoretinal disease

Retinal photocoagulation was initially performed with the argon laser or

xenon arc photocoagulator. The krypton red laser was used with similar eﬃ-
cacy [7,53]. Tunable dye lasers have been used because of their ability to select
wavelengths ranging from blue-green to yellow and red. Although the longer
wavelength of the diode and Nd:YAG lasers causes less scatter through the
ocular media, they have much lower absorption in the RPE and choroid than
the shorter wavelength lasers [7,8,54]. The argon, krypton, and diode lasers
are used most commonly for retinal photocoagulation [17]. The diode,
Nd:YAG, and argon lasers have been recommended for treating tumors and
large vascular anomalies [8,17]. The Er:YAG laser may be well suited for
vitreoretinal surgery because of its precision and limited thermal collateral
damage. To date, the limited uses of Er:YAG laser have included incisions
of epiretinal and subretinal membranes, epiretinal membrane ablation, ret-
inal incisions to relieve retinal contraction, and primary retinal vessel coagu-
lation [47].

The following vitreoretinal diseases have been treated using laser surgery.

Diabetic retinopathy

Nonproliferative diabetic retinopathy is characterized by abnormal struc-

ture of the retinal vessels with subsequent retinal nonperfusion, edema, lipid
exudates, and intraretinal hemorrhages. Proliferative diabetic retinopathy
has characteristics similar to nonproliferative diabetic retinopathy and also
neovascularization of the retina, optic disc, or iris. Vision loss from diabetic
retinopathy can be caused by macular edema, macular ischemia, vitreous
hemorrhage, retinal detachment, or neovascular glaucoma. Diabetic macu-
lar edema is treated by focal or grid photocoagulation when it is adjacent to
or involves the fovea. Proliferative diabetic retinopathy and neovascular
glaucoma are treated by panretinal photocoagulation outside the retinal
vascular arcades [55].

Macular disease

Photocoagulation is used to treat macular choroidal neovascular mem-

branes seen in age-related macular degeneration (ARMD), histoplasmosis,
inﬂammatory diseases, and traumatic choroidal rupture. Photocoagulation
of the aﬀected RPE is performed for idiopathic central serous choroidopa-
thy, characterized by sensory retinal and RPE detachment. Grid pattern

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photocoagulation is used in diabetic macular edema and macular edema
caused by other causes, such as branch retinal vein occlusion. Direct treat-
ment of vascular anomalies is used in retinal vascular disease, such as Coats’
disease and retinal telangiectasias [3]. PDT has recently been approved for
treating choroidal neovascularization in ARMD [14,15], histoplasmosis,
and high myopia (Elaine Chuang, MD, Seattle, WA, personal communica-
tion) to avoid the damage to the overlying retina which occurs with laser
photocoagulation.

Central and branch vein occlusion

Panretinal photocoagulation is used for the treatment of ischemic central

vein occlusion to induce regression of iris or angle neovascularization. Grid
photocoagulation is used for perfused macular edema caused by branch vein
occlusion [56,57]. Sectoral photocoagulation is used to induce regression of
optic disc and retinal neovascularization in branch retinal vein occlusion
(Elaine Chuang, MD, personal communication, 2001).

Retinopathy of prematurity

Photocoagulation with argon or diode lasers is used to treat the early stages

of retinopathy of prematurity. The use of the portable diode laser has allowed
newborns to remain in the neonatal intensive care unit during treatment [7,58].

Neoplasia

Photocoagulation has been used to treat retinoblastoma by either direct

treatment of tumors or by obliterating the feeding and draining vessels and
surrounding capillaries to the tumor [17,59]. Laser photocoagulation has been
reported for the treatment of other posterior segment tumors, including ret-
inal angioma [60], choroidal osteoma [61], and malignant melanoma [17,54].

Retinal breaks

Laser energy is used in the treatment of some rhegmatogenous retinal

detachments to create a chorioretinal adhesion around the tear. Retinal
tears without detachment are treated using laser photocoagulation. Reti-
nal tears with detachment may be treated with laser photocoagulation after
pneumatic retinopexy to create a chorioretinal adhesion after ﬂattening the
retina with a gas bubble. The laser delivery methods include slit lamp, indi-
rect ophthalmoscope, endoprobe during vitrectomy surgery, and transscleral
probe used in combination with scleral buckling [7,17].

Nasolacrimal disease

Nasolacrimal disease uses laser surgery less frequently than other

ophthalmic conditions. Dacryocystorhinostomy for dacryostenosis and
dacryocystitis has been performed using a diode laser with a nasal endo-
scope for visualization [62]. Earlier reports used argon, carbon dioxide

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(CO

), potassium titanyl phosphate (KTP–frequency-doubled YAG), and

Ho:YAG lasers for laser-assisted dacryocystorhinostomy [63].

Laser applications in veterinary ophthalmology

Laser technology was introduced into veterinary ophthalmology in the

1980s. Techniques used in humans were modiﬁed for veterinary patients
and, as comfort level with lasers increased, new applications were explored.
As the technology evolved and familiarity with lasers increased, research in
veterinary applications led to the current use of lasers in clinical settings.
The two most commonly used lasers in veterinary ophthalmology are the
Nd:YAG (1064 nm) and the diode (810 nm). The infrared wavelength of the
diode and Nd:YAG allows safe transmission through the sclera and cornea
and absorption by pigmented intraocular structures. This fact makes their
use appropriate for transscleral cyclophotoablation, intraocular neoplasia,
capsulotomy, and retinopexy. The properties that make the diode especially
attractive to veterinary ophthalmologists include the high absorption of the
diode laser by melanin (which is particularly useful in the typically heavily
pigmented eye of veterinary patients), the portability, small space require-
ment, and low cost (Fig. 1). The CO

laser has been used less frequently.

Extraocular uses of the CO

laser include adnexal, conjunctival, and epi-

scleral lesions. The following reviews the diﬀerent applications of lasers in
veterinary ophthalmology.

Fig. 1. The diode laser (810 nm) used in veterinary ophthalmology is small and portable. It en-
ables transscleral, transcorneal, and transpupillary energy delivery and can be used in a contact
and noncontact mode (IRIS Medical DioVet Laser, IRIDEX Corp., Mountain View, CA).

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Eyelid disease

The CO

laser has been used for various adnexal diseases. Although

transconjunctival ablation of the tarsal glands for the treatment of distichia-
sis has been reported [64], cryoepilation and electrolysis are still the most
commonly used techniques. Interestingly, laser treatment for trichiasis in
humans has not become more popular than standard methods because of
the recurrence of hair growth and, in some cases, eyelid contour abnormal-
ity and hypopigmentation after laser treatment [19]. Various procedures for
entropion correction using the CO

laser have been suggested by clinicians

and promoted by laser manufacturers. The surgical techniques and long-
term results have not been published, however. As in humans, there is no
data to support an overall advantage using the CO

laser for skin blepharo-

plasty incisions compared with the scalpel. The CO

laser does have a valu-

able role for vaporization of eyelid masses, particularly when located
adjacent to the medial canthus making scalpel excision and closure diﬃcult;
for treating diﬀuse eyelid papillomatosis; and for safely extending surgical
margins after excision or debulking of neoplasms, such as ﬁbrosarcoma and
squamous cell carcinoma of the eyelid, limbus, or nictitans. There is less post-
operative inﬂammation after CO

treatment compared with cryosurgery [64].

PDT has not become widely used in veterinary medicine, partly because

of the expense of equipment and specialized training required [65]. The
ophthalmic applications of PDT in veterinary ophthalmology may be most
signiﬁcant in the treatment of eyelid squamous cell carcinoma in cats; a con-
dition that is highly malignant and diﬃcult to excise adequately without
sacriﬁcing the globe. To date, promising results have been obtained using
PDT to treat facial squamous cell carcinoma in cats [65,66].

Corneal, conjunctival, limbal, and episcleral disease

Because of the limited signiﬁcance of refractive errors in veterinary

patients and the low rate of clinically signiﬁcant myopia and hyperopia in
dogs [67–69], refractive surgery has not evolved in veterinary ophthalmol-
ogy. One study performing keratomileusis with the excimer laser on normal
dogs showed successful corneal healing and a reduction in refractive power
by an average of 9.55 diopters. The authors of that study suggested that
refractive surgery for hyperopia in the dog may replace implantation of
intraocular lenses after cataract removal [70]. This is very unlikely given the
diﬃculty of mastering the technique, the expense of the equipment involved,
and the risk of complications in corneal healing, such as neovascularization,
ﬁbrosis, and pigmentation. Also, hyperopia correction in humans has
proved much more challenging than myopia correction, and reﬁnements
continue to be made. The excimer laser has been used successfully to treat
superﬁcial crystalline corneal dystrophy in a dog. Re-epithelialization oc-
curred within seven days with a smoother, clearer, anterior surface com-
pared with traditional surgical keratectomy. Although the laser successfully

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removed superﬁcial pigmentation in two Pugs, the pigment returned after 8
months [71]. The overall high success rate of traditional surgical techniques
(ie, grid keratotomy, keratectomy) and the expense of the excimer laser will
likely preclude it from becoming popular in veterinary ophthalmology for
treatment of epithelial and anterior stromal corneal diseases, such as indo-
lent ulcers, corneal dystrophy, superﬁcial scars, and sequestrums. Although
not documented in controlled studies, some clinicians have advocated the
use of the CO

laser for corneal surface vaporization to treat corneal ulcers.

More studies that evaluate the acute and chronic eﬀects are needed before
this technique can be recommended.

The diode, Nd:YAG, and CO

lasers are routinely used for the ablation

of limbal (epibulbar) melanoma in dogs and cats with a high success rate
[72,73]. Compared with scalpel excision, the use of the laser is less invasive,
less technically diﬃcult, and faster because of excellent hemostasis. Immedi-
ate eﬀects of laser treatment are charring and contraction of the pigmented
tissue. The Nd:YAG or diode laser requires that care be taken to ensure that
the beam does not penetrate the cornea or sclera, damaging intraocular
structures. Treatment with the diode laser has been successful using the
operating microscope adapter, the laser indirect ophthalmoscope with a
20-diopter lens, and the glaucoma probe and transscleral retinopexy probe
used in a noncontact mode.

The CO

laser has been used successfully to treat nictitans and limbal

squamous cell carcinomas in the horse [64,74]. The advantages of CO

laser

over scalpel excision include excellent hemostasis and less postoperative
inﬂammation and discomfort. Also, compared with scalpel excision, the
incidence of tumor recurrence may be less with CO

laser ablation because

of a zone of cellular destruction extending beyond the gross margins of abla-
tion. A disadvantage of CO

laser ablation noted in one study was the sub-

jectively slower corneal and conjunctival re-epithelialization [74].

Glaucoma

Ablation of ciliary body tissues has been used to treat glaucoma in dogs,

cats, and horses. The intent is to destroy enough tissue to lower the overall
production of aqueous, thereby lowering the intraocular pressure (IOP) in
the eye. Although the primary target tissue is the ciliary epithelium, vascular
damage, decreased ciliary surface area, ciliary body atrophy, and increased
uveoscleral outﬂow may be secondary mechanisms contributing to
decreased IOP [12]. Cyclocryoablation using liquid nitrogen or nitrous oxide
was the ﬁrst modality used and the standard for comparison of laser cyclo-
photoablation (cyclophotocoagulation). Complications of cyclocryoabla-
tion included considerable uveitis, posttreatment intraocular pressure
elevation, phthisis bulbi, and retinal detachment. Although most authors
cite less inﬂammation with cyclophotoablation than cyclocryoablation, one
study performed in normal dogs showed signiﬁcantly more uveitis in the

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group receiving Nd:YAG noncontact cyclophotoablation [75]. Because the
thermal tissue destruction with the laser is more exact, there is less collateral
damage with the laser than with cryosurgery [76]. Classic histologic changes
seen after cyclophotoablation are coagulation necrosis of the nonpigmented
and pigmented ciliary epithelium with coagulation of the ciliary stroma and
its vasculature [12]. In general, animals with lightly pigmented uvea require
higher laser energy, repeated treatments, and have a signiﬁcantly higher rate
of failure to control IOP [76].

The Nd:YAG was the ﬁrst laser used for cyclophotoablation in the dog.

Using noncontact mode, 5 mm posterior to the limbus, a study of normal dogs
showed a signiﬁcant decrease in IOP, mild to severe posttreatment uveitis
depending on the amount of energy delivered, and no posttreatment IOP ele-
vation. The histologic eﬀects in eyes receiving an average of 238 J was coagu-
lation necrosis of the ciliary body shown by disruption of the pigmented and
nonpigmented ciliary epithelium by day 7 and by severe ciliary body atrophy
by day 28 [77]. When the Nd:YAG laser was used in the contact mode at 126,
154, and 212 J, a study of normal dogs showed a signiﬁcant decrease in IOP,
mild to severe posttreatment uveitis depending on the amount of energy deliv-
ered, cataractous changes, and a posttreatment IOP elevation in the high
energy treatment group. Histologic changes at day 28 ranged from mild dis-
ruption of melanocytes within the ciliary body and processes to extensive dis-
ruption of the ciliary epithelial layers and severe ciliary atrophy, depending on
the amount of energy delivered [78]. Comparing these two studies, the non-
contact mode is associated with less complications, particularly cataract and
posttreatment IOP elevation, with equivalent tissue damage.

In dogs with glaucoma, noncontact Nd:YAG cyclophotoablation, with

an average of 222 J delivered per eye, resulted in an overall reduction in IOP.
Even with ancillary glaucoma treatment, however, it took an average of
5 weeks for the IOP to reach normal range (less than 25 mmHg). No signiﬁ-
cant decrease in IOP was noted in eyes treated prophylactically with an aver-
age of 250 J per eye. There was also no eﬀect seen in glaucomatous eyes with
nonpigmented uveal tissue. Cataracts were noted as a complication [79].
Other authors cite rapid decrease in IOP with minimal postprocedure
inﬂammation using the noncontact Nd:YAG at 240 J per eye (0.5 seconds,
16 W, 30 sites) [80] and using slower energy delivery at 300 J per eye (10 sec-
onds, 5 W, 6 sites and 7.5 seconds, 5 W, 8 sites) [81].

Noncontact Nd:YAG cyclophotoablation, 3 mm posterior to the limbus,

was evaluated in normal cats and showed a clinical decrease in IOP (maxi-
mum at 4 to 8 weeks) and histologic focal areas of disruption of the pig-
mented and nonpigmented cells of the ciliary body 6 weeks after treatment
[82,83]. Aqueous outﬂow and ciliary body blood ﬂow were not altered, thus
indicating that the primary cause for decreased IOP is reduced aqueous pro-
duction from damage to the ciliary body epithelium rather than from ische-
mia or increased outﬂow [83]. Clinically cyclophotoablation in glaucomatous
cat eyes does not seem as eﬀective as in dogs [84].

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Cyclophotoablation with the Nd:YAG laser has been used successfully

for glaucoma in the horse using the laser in a contact mode, 5 to 6 mm pos-
terior to the limbus, and a range of 154 to 438 J of laser energy applied to
each eye (mean

¼ 270 J). Laser cyclophotoablation proved very eﬀective (1)

in controlling IOP long term, and in some horses without the addition of
medical therapy; (2) in preserving but not regaining vision; and (3) in reduc-
ing buphthalmia [85,86]. Complications were few and included hyphema,
cataract, ﬁbrin, superﬁcial corneal ulcer, and phthisis bulbi [85,86].

The diode laser’s shorter wavelength (810 nm) has lower scleral transmis-

sion compared with the Nd:YAG but better absorption by melanin. When
used in a contact mode, scleral transmission is improved, particularly if
scleral indentation is applied. It has been suggested that the lower total energy
required and the use of lower power with longer duration results in less tissue
side eﬀects compared with the Nd:YAG [87]. A study evaluating the eﬀects of
cyclophotoablation with the diode laser in normal dog eyes, using an average
of 79 J per eye (1.5 W

1.5 seconds per site) 3 mm posterior to the limbus,

showed no initial IOP elevation and no cataract. Histologic changes were
similar to the Nd:YAG, but were obtained with lower energy [87].

Clinical studies on glaucomatous eyes using the diode laser have shown

decreased IOP. In a large study using the diode laser for cyclophotoablation
in dogs, each eye averaged 85 J (1.5 W

1.5 seconds per site). Signiﬁcant

complications included an immediate posttreatment IOP spike in most eyes
and corneal ulceration, cataract, intraocular hemorrhage, and retinal
detachment in a few eyes. An average IOP of 25 mmHg was achieved by the
ﬁrst 1 to 2 hours, which was maintained over 6 to 12 months. IOP was suc-
cessfully controlled in 65% of eyes at 6 months. Of the eyes that were initi-
ally visual, 37% were still visual at 6 months [84]. Two smaller studies using
higher total energy per eye (125 J) with lower power and longer duration
(1.0 W

5 seconds per site) suggest that this protocol produces less compli-

cations, such as postprocedural IOP spike and better IOP control. In the
study evaluating dogs with secondary glaucoma, IOP was controlled in 8
of 8 eyes [88]. In the study evaluating dogs with primary glaucoma, IOP was
controlled in 23 of 24 eyes, with three of those eyes requiring a second treat-
ment. Twenty-one percent had an immediate IOP spike. Fifty-ﬁve percent
of dogs with a potential for regaining vision did so [89]. Complications
in both studies included cataract and corneal ulceration. Interestingly, cyclo-
photoablation for secondary glaucoma performed on ﬁve cats with an
average of 152 to 200 J per eye all failed to control IOP [88]. A study com-
bining cyclophotoablation and gonioimplantation suggested a lower inci-
dence of postoperative IOP spike (37%) than with cyclophotoablation
alone [90].

Although both the Nd:YAG and diode lasers are capable of lowering

IOP, in comparable clinical studies of glaucomatous dog eyes, control of
IOP at an average of 25 mmHg was achieved much faster with the diode
(hours) than the Nd:YAG (weeks). In both groups, the IOP was then

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maintained for 6 months in most cases. Intraocular complications, presum-
ably caused by the eﬀects of laser energy or the secondary inﬂammatory
response, were similar for both lasers, although the incidence of cataract
appears higher with contact Nd:YAG cyclophotocoagulation [78]. The
cause of corneal ulceration is not as obvious. Lagophthalmos has been pro-
posed [76], as has neurotropic keratitis caused by laser-induced damage to
corneal innervation [91]. Neurotrophic corneal defects have been reported
in humans as a complication after diode laser cycloablation [92]. Both the
Nd:YAG and the diode lasers produce similar histologic changes
[77,87,93] and similar thermal eﬀects at the level of the ciliary body, includ-
ing peak temperature, area of peak temperature, and decay times [93].

Few published reports exist concerning the use of the diode laser for

cycloablation in horses. One study of glaucoma in horses includes a single
case in which the diode laser was used to control glaucoma secondary to
chronic uveitis. Eight weeks into treatment, laser cycloablation was per-
formed. IOP did not decrease initially even after two more treatments; how-
ever, long-term IOP control was achieved [94]. Clinically, the diode laser is
used routinely in horses with glaucoma unresponsive to medical therapy.

Other less common procedures for glaucoma using the Nd:YAG laser

include synechiotomy, capsulotomy, and iridotomy for pupillary block glau-
coma [64,95] and hyaloidotomy for malignant glaucoma [95]. Immediate
complications after laser use included hyphema and ﬁbrin. All iridotomies
eventually closed and generally remained patent for less than 1 week.
Long-term success (up to 4 years) was observed with synechiotomies [95].
A pilot study evaluating the diode laser for iridotomy, using a direct
ophthalmoscope delivery system, a spot size of 0.15 mm, and various power
(200 to 1200 mW) and duration (200 to 5000 msec) settings failed to create a
visibly patent iridotomy either grossly or histologically [96]. Filtering proce-
dures, such as sclerostomy, have not proved to have long-term success in the
dog as evidenced by a study using the Nd:YAG to create a sclerostomy,
which was closed by ﬁbroblastic proliferation within 2 weeks [97].

Capsulotomy

The Nd:YAG laser is used for posterior capsulotomy of an opaciﬁed cap-

sule after extracapsular cataract removal in the dog [64,98,99]. By using the
Q-switching mode, the laser energy can be emitted in extremely short pulses
producing a photodisruptive eﬀect on the target tissue. In one study of 33
capsulotomies in canine aphakic eyes, the success rate was 75%. Capsulo-
tomy failure was usually caused by increased density of the capsular opacity.
Complications included aqueous ﬂare in all patients, and iris hemorrhage
and iris bombe´ in a few patients [99]. Although surgical posterior capsulo-
tomy can be performed quite easily without the laser in aphakic eyes, it is
much more diﬃcult in pseudophakic eyes, thus making the Nd:YAG laser
capsulotomy particularly useful for pseudophakic eyes.

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Anterior uveal cysts and tumors

The diode and Nd:YAG lasers are ideal for treating large uveal cysts and

cystic corpora nigra. Treatment is indicated when cysts interfere with vision
or aqueous outﬂow. In one study the Nd:YAG laser in Q-switching mode
and focused through a slit lamp biomicroscope was used to rupture cystic
corpora nigra in eight horses. Focusing the laser energy burst at the apex
of the cyst resulted in no complications, and vision deﬁcits resolved imme-
diately in all horses [100].

Both the diode and Nd:YAG lasers are used to treat primary intraocular

neoplasia in the dog. This use has been a signiﬁcant advancement in veteri-
nary ophthalmology, because before laser availability the diﬃculty in success-
fully excising uveal tumors led most clinicians to not treat until secondary
uveitis or glaucoma necessitated enucleation or evisceration. Laser energy
can be delivered transsclerally or ab interno using a sterile ﬁber inserted
through the opposite pars plana for ciliary body tumors. For iris tumors,
laser energy is directed through the cornea using the slit lamp, indirect
ophthalmoscope, or operating microscope. A study evaluating the Nd:YAG
laser for ciliary body and iris tumors suggested response to treatment
depended more on extent of the tumor and less on the degree of pigmentation
of the tumor. A better success rate was seen in tumors that involved only the
ciliary body or the iris; results were less favorable when ciliary body tumors
extended into the iris or sclera. Focal, nonprogressive cataracts developed in
eyes with tumors in close proximity to the lens [101]. Another study evaluated
the use of the diode laser to treat presumed iris melanoma in 23 dogs. Regres-
sion of the tumor occurred in all cases, with 5 of 23 dogs requiring retreat-
ment. Best results were obtained by maximizing thermal eﬀects using lower
power, longer duration, and larger spot size. Minor complications included
dyscoria, iris atrophy, iris hyperpigmentation, and focal corneal edema
caused by collateral hyperthermia in eyes with tumors in close proximity to
the cornea [102]. In contrast to dogs, iris melanoma in cats has a higher meta-
static potential. This fact has resulted in much more caution when treating
iris-pigmented lesions in cats; although laser-induced hematogenous spread
of neoplastic cells has not been documented [102].

Retinal detachment

Vitreoretinal laser surgery has not evolved in veterinary ophthalmology

to the enormous extent it has in human ophthalmology. This is because
of the limited indications in veterinary patients compared with huge appli-
cations in humans, such as diabetic retinopathy and macular disease. Cur-
rently, the diode laser, with either transscleral or transpupillary delivery,
is most commonly used for retinopexy in veterinary ophthalmology. Retino-
pexy is performed either prophylactically or for the treatment of rhegmato-
genous retinal detachment. Prophylactic retinopexy indications in the dog

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include pre- or postintracapsular lens extraction, pre- or postphacoemulsiﬁ-
cation of a hypermature cataract, the fellow eye of a dog with a giant retinal
tear, and at the margins of a colobomatous optic disc. When used in asso-
ciation with cataract surgery, laser energy will be delivered more precisely if
the retinopexy is performed postoperatively.

In 1989, Vainisi and Packo reported treating 24 dogs with serous retinal

detachment associated with optic disc pits using a xenon arc photocoagulator.
A continuous row of photocoagulation spots were placed along the retinal
detachment adjacent to the disc. In all but one dog (who had an extensive ret-
inal detachment), subretinal ﬂuid resorbed completely. Although the areas of
detachment resulted in varying degrees of retinal degeneration, the goal of
preventing extension of the retinal detachment was achieved [103].

Using intraocular delivery, diode laser endophotocoagulation has been

used with retinal tacks and silicone oil for the repair of giant retinal tears
in dogs [104].

Transscleral retinopexy with the diode laser can be used for peripheral ret-

inal tears and for prophylactic retinopexy. Transscleral retinopexy is best per-
formed with direct visualization by indirect ophthalmoscopy of the retina and
laser-aiming beam, using scleral depression if needed. Energy is titrated to the
desired endpoint of observing a gray retinal lesion. For prophylactic trans-
scleral retinopexy, 0.2 to 0.5 J per site have been used to treat all four quad-
rants or just the superior quadrant. Placement of the photocoagulation spots
should provide a contiguous chorioretinal adhesion in the area at risk without
being overzealous and causing hemorrhage or full-thickness retinal holes [105].
In a study using the diode transscleral retinopexy probe in normal canine
eyes, settings of 800 msec and 400 mW produced a white to gray spot when
viewed by indirect ophthalmoscopy and caused scleral thinning, choroidal
thinning and RPE migration into the choroid and retina histologically [106].

Transpupillary retinopexy with the diode laser uses the laser indirect

ophthalmoscope and a 20 diopter lens (Fig. 2). Retinal holes can be treated
circumferentially to prevent detachment. The edge of a serous detachment
from a retinal tear or optic disc coloboma can be treated to prevent further
extension of the subretinal ﬂuid. Adequate treatment of the tapetal fundus
is more diﬃcult because of the lack of melanin in the RPE. A study evaluating
the clinical and pathologic eﬀects of diﬀerent power settings in the canine fun-
dus showed the amount of laser energy required varied considerably based on
the amount of RPE pigment present. Grossly, lesions in the nontapetal fundus
were easily visible as being gray to white spots; however, in the tapetal fundus,
lesions were harder to see, more so in yellow tapetum than the green, and they
appeared bronze or dark green. Histologically, in the tapetal fundus, the laser
energy was absorbed by choroidal melanocytes with the photocoagulative
eﬀect dependent on the amount of choroidal melanin and the thickness of the
tapetum. It was possible to produce discrete lesions that spared the inner ret-
inal layers. Recommended settings for the nontapetal fundus were 100
mW

300 msec for the periphery and 150 mW 300 msec for the center.

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Recommended settings for the tapetal fundus were 150 mW

300 msec for

the periphery and an average of 200 mW

300 msec in the center [107].

Laser safety and the eye

No discussion of lasers is complete without mention of safety, and the

ophthalmic use of lasers is no exception. Because ophthalmology uses lasers
of varying wavelengths, it is important to be aware of the damage each laser
can cause to the eye of the patient and operating room personnel. The eye
damage that laser radiation causes depends on the wavelength, the intensity
of the radiation, and the absorption characteristics of the eye tissues [108].
Wavelengths between 100 and 315 nm are absorbed by the corneal surface,
producing a temporary photokeratitis. Wavelengths between 315 and 400
nm are primarily absorbed by the lens, resulting in cataract formation. Wave-
lengths between 400 and 1400 nm are transmitted through the clear ocular
media to the retina. Wavelengths between 400 and 700 nm are in the visible
spectrum so the recipient is aware of the exposure; however, wavelengths
between 700 and 1400 nm are not in the visible spectrum so the exposure and
subsequent retinal damage may go undetected. Wavelengths between 1400
and 10,600 nm are absorbed by the cornea, resulting in corneal (or scleral)
burns. Wavelengths between 1400 and 3000 nm may penetrate deeper causing
heating of lens proteins and cataract formation [108]. Laser safety eyewear
must be worn that is speciﬁc for the wavelength of laser being used. When
laser energy is applied to the eyelids, the patient’s eye should be protected
by a nonreﬂective stainless steel or lead eye shield [109]. Although lubricating
ointments are commonly used in the eye for protection during surgical pro-
cedures, a recent case report suggests that petroleum-based lubricants may

Fig. 2. The diode laser (810 nm) can be used with the laser indirect ophthalmoscope for
transcorneal delivery of laser energy to treat iris tumors and for transpupillary delivery to treat
retinal tears and detachments. (Courtesy of the IRIDEX Corp.)

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M.A. Gilmour / Vet Clin Small Anim 32 (2002) 649–672

ignite when used in proximity to a laser [110]. Water-based lubricants appear
to be safer for laser procedures.

Summary

Laser technology continues to progress with the addition of new lasers,

new delivery systems, and new applications. The introduction of lasers to
veterinary ophthalmology has radically changed the level of care that we can
provide to our patients. The development of the diode laser has particularly
had an impact on veterinary ophthalmology. The diode’s aﬀordability, port-
ability, and broad applications for veterinary patients have allowed laser
surgery to become a routine part of veterinary ophthalmology practice.
Educating the public and veterinary community in available laser techniques
will generate improved ophthalmic care and provide more data on which to
build future applications.

References

[1] Marshall J. Lasers in ophthalmology: the basic principles. Eye 1988;2(Suppl):S98–112.
[2] Balles MW, Puliaﬁto CA. Semiconductor diode lasers: a new laser light source in oph-

thalmology. Int Ophthalmol Clin 1990;30(2):77–83.

[3] Bass SJ, Giovinazzo V. Laser treatment of macular disease. Optom Clin 1996;5(1):161–73.
[4] Raivio VE, Immonen IJR, Laatikainen LT, et al. Transscleral contact krypton laser cyclo-

photocoagulation for treatment of posttraumatic glaucoma. J Glaucoma 2001;10(2):77–84.

[5] Smith RS, Stein MN. Ocular hazards of transscleral laser radiation. Am J Ophthalmol 1968;

66(1):21–31.

[6] Vogel A, Dlugos C, Nuﬀer R, et al. Optical properties of human sclera, and their con-

sequences for transscleral laser applications. Lasers Surg Med 1991;11:331–40.

[7] Dyer DS, Bressler SB, Bressler NM. The role of laser wavelength in the treatment of

vitreoretinal diseases. Curr Opin Ophthalmol 1994;5(3):35–43.

[8] Roider J. Laser treatment of retinal diseases by subthreshold laser eﬀects. Semin Oph-

thalmol 1999;14(1):19–26.

[9] Ulbig MW, McHugh DA, Hamilton AMP. Diode laser photocoagulation for diabetic

macular oedema. Br J Ophthalmol 1995;79(4):318–21.

[10] Callina TL, Hunts JH. Applications of CO

laser in oculoplastic surgery. J Ophthalmic

Nurs Technol 1999;18(3):95–9.

[11] Infeld DA, O’Shea JG. Excimer laser ophthalmic surgery: evaluation of a new technology.

Postgrad Med J 1998;74(875):524–8.

[12] Chen TC, Pasquale LR, Walton DS, et al. Diode laser transscleral cyclophotocoagulation.

Int Ophthalmol Clin 1999;39(1):169–76.

[13] Moriarty AP. Diode lasers in ophthalmology. Int Ophthalmol 1993;17(6):297–304.
[14] Donati G, Kapetanios AD, Pournaras CJ. Principles of treatment of choroidal neo-

vascularization with photodynamic therapy in age-related macular degeneration. Semin
Ophthalmol 1999;14(1):2–10.

[15] Regillo CD. Update on photodynamic therapy. Curr Opin Ophthalmol 2000;11(3):166–70.
[16] Gohto Y, Obana A, Kanai M, et al. Photodynamic therapy for corneal neovascularization

using topically administered ATX-S10(Na). Ophthalmic Surg Lasers 2000;31(1):55–60.

[17] Leﬀell DJ, Thompson JT. Lasers in dermatology and ophthalmology. Dermatol Clin

1992;10(4):687–700.

668

M.A. Gilmour / Vet Clin Small Anim 32 (2002) 649–672

[18] Roberts TL. Laser blepharoplasty and laser resurfacing of the periorbital area. Clin Plast

Surg 1998;25(1):95–108.

[19] Tayani R, Rubin PA. Laser applications in oculoplastic surgery and their postoperative

complications. Int Ophthalmol Clin 2000;40(1):13–26.

[20] Lessner AM, Fagien S. Laser blepharoplasty. Semin Ophthalmol 1998;13(3):90–102.
[21] American Academy of Ophthalmology. Laser blepharoplasty and skin resurfacing.

Ophthalmology 1998;105(11):2154–59.

[22] Paparo LG, Rapuano CJ, Raber IM, et al. Phototherapeutic keratectomy for Schnyder’s

crystalline corneal dystrophy. Cornea 2000;19(3):343–7.

[23] Telfair WB, Bekker C, Hoﬀman HJ, et al. Histological comparison of corneal ablation

with Er:YAG laser, Nd:YAG optical parametric oscillator, and excimer laser. J Refract
Surg 2000;16(1):40–50.

[24] Stein R. Photorefractive keratectomy. Int Ophthalmol Clin 2000;40(3):35–56.
[25] Excimer laser photorefractive keratectomy (PRK) for myopia and astigmatism. Oph-

thalmology 1999;106(2):422–37.

[26] Farah SG, Azar DT, Gurdal C, et al. Laser in situ keratomileusis: literature review of a

developing technique. J Cataract Refract Surg 1998;24(7):989–1006.

[27] O’Brart DP. The status of hyperopic laser-assisted in situ keratomileusis. Curr Opin

Ophthalmol 1999;10(4):247–52.

[28] Habib MS, Speaker MG, Kaiser R, et al. Myopic intrastromal photorefractive kera-

tectomy with the neodymium-yttrium lithium ﬂuoride picosecond laser in the cat cornea.
Arch Ophthalmol 1995;113(4):499–505.

[29] Gimbel HV, Coupland SG, Ferensowicz M. Review of intrastromal photorefractive

keratectomy with the neodymium-yttrium lithium ﬂuoride laser. Int Ophthalmol Clin 1997;
37(1):95–102.

[30] Telfair WB, Bekker C, Hoﬀman HJ, et al. Healing after photorefractive keratectomy in

cat eyes with a scanning mid-infrared Nd:YAG pumped optical parametric oscillator
laser. J Refract Surg 2000;16:32–9.

[31] Ren Q, Simon G, Parel JM. Noncontact laser photothermal keratoplasty III: histological

study in animal eyes. J Refract Corneal Surg 1994;10(5):529–39.

[32] Stulting RD, Lahners WJ, Carr JD. Advances in refractive surgery. Cornea 2000;19(5):

741–53.

[33] Thompson VM, Seiler T, Durrie DS, et al: Holmium:YAG laser thermokeratoplasty

for hyperopia and astigmatism: an overview. Refract Corneal Surg 1993;9(Suppl 2):S134–7.

[34] Fleming JB. Laser therapy and angle-closure glaucoma. Optom Clin 1995;4(4):97–111.
[35] American Academy of Ophthalmology. Laser peripheral iridotomy for pupillary-block

glaucoma. Ophthalmology 1994;101(10):1749–58.

[36] Carenini BB, Nuzzi R. Laser treatment of glaucoma. Curr Opin Ophthalmol 1992;3(2):

178–89.

[37] Ritch R, Liebmann JM. Argon laser peripheral iridoplasty. Ophthalmic Surg Lasers 1996;

27(4)289–300.

[38] Talley DK. Laser therapy for open-angle glaucoma. Optom Clin 1995;4(4):85–96.
[39] Park CH, Latina MA, Schuman JS. Developments in laser trabeculoplasty. Ophthalmic

Surg Lasers 2000;31(4):315–22.

[40] Threlkeld AB, Hertzmark E, Sturm RT, et al. Comparative study of the eﬃcacy of argon

laser trabeculoplasty for exfoliation and primary open-angle glaucoma. J Glaucoma
1996;5(5):311–6.

[41] Jacobi PC, Dietlein TS, Krieglstein GK. Perspectives in trabecular surgery. Eye

2000;14(3b):519–30.

[42] Pappas RM, Higginbotham EJ, Choe HS. Advances in laser sclerostomy: how far have we

come? Ophthalmic Surg Lasers 1997;28(9):751–7.

[43] Wetzel W, Scheu M. Laser sclerostomy ab externo using mid infrared lasers. Ophthalmic

Surg 1993;24(1):6–12.

669

M.A. Gilmour / Vet Clin Small Anim 32 (2002) 649–672

[44] Oh Y, Katz LJ. Indications and technique for reopening closed ﬁltering blebs using the

Nd:YAG laser—A review and case series. Ophthalmic Surg 1993;24(9):617–22.

[45] Dickens CJ, Nguyen N, Mora JS, et al. Long-term results of noncontact transscleral

neodymium:YAG cyclophotocoagulation. Ophthalmology 1995;102(12):1777–81.

[46] Jacobi PC, Dietlein TS. Endoscopic surgery in glaucoma management. Curr Opin Oph-

thalmol 2000;11(2):127–32.

[47] D’Amico DJ, Blumenkranz MS, Lavin MJ, et al. Multicenter clinical experience using an

erbium:YAG laser for vitreoretinal surgery. Ophthalmology 1996;103(10):1575–85.

[48] Weiblinger RP. Review of the clinical literature on the use of the Nd:YAG laser for

posterior capsulotomy. J Cataract Refract Surg 1986;12(2):162–70.

[49] Aasuri MK, Basti S. Laser-assisted cataract surgery and other emerging technologies for

cataract removal. Indian J Ophthalmol 1999;47(4):215–22.

[50] Dodick JM, Lally JM. Sperber LTD: Lasers in cataract surgery. Curr Opin Ophthalmol

1993;4(1):107–9.

[51] Neubaur CC, Stevens G. Erbium: YAG laser cataract removal: role of ﬁber-optic delivery

system. J Cataract Refract Surg 1999;25(4):514–20.

[52] Stevens G, Long B, Hamann JM. Erbium: YAG laser-assisted cataract surgery. Oph-

thalmic Surg Lasers 1998;29(3):185–9.

[53] Slakter JS. Recent developments in ophthalmic lasers. Curr Opin Ophthalmol 1992;3(1):

83–93.

[54] Fankhauser F, Giger H, Niederer P, et al. Transpupillary laser phototherapy of tumors

and vascular anomalies of retina and choroid: theoretical approach and clinical impli-
cations. Technol Health Care 2000;8(2):93–112.

[55] Neely KA, Quillen DA, Schachat AP. Diabetic retinopathy. Med Clin North Am 1998;

82(4)847–76.

[56] Finkelstein D. Laser therapy for central retinal vein obstruction. Curr Opin Ophthalmol

1996;7(3):80–3.

[57] Finkelstein D. Laser treatment of macular edema resulting from branch vein occlusion.

Semin Ophthalmol 1994;9(1):23–8.

[58] McNamara JA. Laser treatment for retinopathy of prematurity. Curr Opin Ophthalmol

1993;4(3):76–80.

[59] Shields JA, Shields CL, DePotter P. Photocoagulation of retinoblastoma. Int Ophthalmol

Clin 1993;33(3):95–9.

[60] Gorin MB. Von Hippel-Lindau disease: clinical considerations and the use of ﬂuorescein-

potentiated argon laser therapy for treatment of retinal angiomas. Semin Ophthalmol 1992;
7(3):182–91.

[61] Rose SL, Burke JF, Brockhurst RJ. Argon laser photoablation of a choroidal osteoma.

Retina 1991;11:224–8.

[62] Eloy P, Trussart C, Jouzdani E, et al. Transcanalicular diode laser assisted dacryo-

cystorhinostomy. Acta Otorhinolaryngol Belg 2000;54(2):157–63.

[63] Hobson SR. Endoscopic surgery for lacrimal and orbital disease. Curr Opin Ophthalmol

1994;5(5):32–8.

[64] Nasisse MP, Davidson MG. Laser therapy in veterinary ophthalmology: perspective and

potential. Semin Vet Med Surg Small Anim 1988;3(1):52–61.

[65] Lucroy MD, Edwards BF, Madewell BR. Veterinary photodynamic therapy. J Am Vet

Med Assoc 2000;216(11):1745–51.

[66] Chang CL, Lai YL, Wong CJ. Photodynamic therapy for facial squamous cell carcinoma

in cats using Photofrin. Changgeng Yi Xue Za Zhi 1998;21(1):13–9.

[67] Gaiddon J, Bouhana N, Lallement PE. Refraction by retinoscopy of normal, aphakic, and

pseudophakic canine eyes: advantage of a 41-diopter intraocular lens? Vet Comp
Ophthalmol 1996;6(2):121–4.

[68] Murphy CJ, Zadnik K, Mannis MJ. Myopia and refractive error in dogs. Invest Oph-

thalmol Vis Sci 1992;33(8):2459–63.

670

M.A. Gilmour / Vet Clin Small Anim 32 (2002) 649–672

[69] Pollet L. Refraction of normal and aphakic canine eyes. J Am Anim Hosp Assoc 1982;18:323–6.
[70] Rosolen SG, Ganem S, Gross M, et al. Refractive corneal surgery on dogs: preliminary

results of keratomileusis using a 193 nanometer excimer laser. Vet Comp Ophthalmol
1995;5(1):18–24.

[71] Shieh E, Boldy KL, Garbus J. Excimer laser keratectomy in the treatment of canine

corneal opacities. Prog Vet Comp Ophthalmol 1992;2(2):75–9.

[72] Sullivan TC, Nasisse MP, Davidson MG, et al. Photocoagulation of limbal melanoma in

dogs and cats: 15 cases (1989–1993). J Am Vet Med Assoc 1996;208(6):891–4.

[73] Wilkie DA, Whittaker C. Surgery of the cornea. Vet Clin North Am Small Anim Pract

1997;27(5):1067–107.

[74] English RV, Nasisse MP, Davidson MG. Carbon dioxide laser ablation for treatment of

limbal squamous cell carcinoma in horses. J Am Vet Med Assoc 1990;196(3):439–42.

[75] Ring RD, Ward DA, Schmidt DE. Comparison of cyclophotocoagulation and cyclo-

cryosurgery in the dog. In: Proceedings of the 28th Annual Meeting American College of
Veterinary Ophthalmologists, Santa Fe (NM); 1997. p. 43.

[76] Cook CS. Surgery for glaucoma. Vet Clin North Am Small Anim Pract 1997;27(5):1109–29.
[77] Nasisse MP, Davidson MG, MacLachlan J, et al. Neodymium:yttrium, aluminum, and

garnet laser energy delivered transsclerally to the ciliary body of dogs. Am J Vet Res
1988;49(11):1972–8.

[78] Sapienza JS, Miller TR, Gum GG, et al. Contact transscleral cyclophotocoagulation using

a neodymium:yttrium aluminum garnet laser in normal dogs. Prog Vet Comp Ophthalmol
1992;2(4):147–53.

[79] Nasisse MP, Davidson MG, English RV, et al. Treatment of glaucoma by use of

transscleral neodymium:yttrium aluminum garnet laser cyclocoagulation in dogs. J Am
Vet Med Assoc 1990;197(3):350–4.

[80] Brooks DE. Glaucoma in the dog and cat. Vet Clin North Am Small Anim Pract 1990;

20(3):775–97.

[81] Wolfer J, Wyman D, Wilson B. Use of a non-contact neodymium:yttrium aluminum garnet

laser in the treatment of canine glaucoma. In: Proceedings of the 24th Annual Meeting of
the American College of Veterinary Ophthalmologists, Scottsdale (AZ); 1993. p. 138.

[82] Rosenberg LF, Burchﬁeld JC, Krupin T, et al. Cat model for intraocular pressure reduction

after transscleral Nd:YAG cyclophotocoagulation. Curr Eye Res 1995;14:255–61.

[83] Rosenberg LF, Karalekas DP, Krupin T, et al. Cyclocryotherapy and noncontact Nd:YAG

laser cyclophotocoagulation in cats. Invest Ophthalmol Vis Sci 1996;37(10):2029–36.

[84] Cook C, Davidson M, Brinkman M, et al. Diode laser transscleral cyclophotocoagulation

for the treatment of glaucoma in dogs: results of six and twelve month follow-up. Vet
Comp Ophthalmol 1997;7(3):148–54.

[85] Miller TR, Brooks DE, Gelatt KN. Equine glaucoma: clinical ﬁndings and response to

treatment in 14 horses. Vet Comp Ophthalmol 1995;5(3):170–82.

[86] Whigham HM, Brooks DE, Andrew SE, et al. Treatment of equine glaucoma by

transscleral neodymium:yttrium aluminum garnet laser cyclophotocoagulation: a retro-
spective study of 23 eyes of 16 horses. Vet Ophthalmol 1999;2(4):243–50.

[87] Nadelstein B, Wilcock B, Cook C, et al. Clinical and histopathologic eﬀects of diode laser

transscleral cyclophotocoagulation in the normal canine eye. Vet Comp Ophthalmol
1997;7(3):155–62.

[88] Hardman C, Stanley RG. Diode laser transscleral cyclophotocoagulation for the

treatment of secondary glaucoma in dogs and cats. In: Proceedings of the 29th Annual
Meeting of the American College of Veterinary Ophthalmologists. Seattle: American
College of Veterinary Ophthalmologists; 1998. p. 23.

[89] Hardman C, Stanley RG. Diode laser transscleral cyclophotocoagulation for the treatment

of primary glaucoma in dogs a retrospective study. In: Proceedings of the 29th Annual
Meeting of the American College of Veterinary Ophthalmologists. Seattle: American
College of Veterinary Ophthalmologists; 1998. p. 24.

671

M.A. Gilmour / Vet Clin Small Anim 32 (2002) 649–672

[90] Bentley E, Miller PE, Murphy CJ, et al. Combined cycloablation and gonioimplantation for

treatment of glaucoma in dogs: 18 cases (1992–1998). J Am Vet Med Assoc 1999;215(10):
1469–72.

[91] Weigt AK, Pickett JP, Herring IP. The eﬀects of Nd:YAG laser photocoagulation on

corneal touch threshold, aqueous tear production, and intraocular pressure in the canine
cornea. In: Proceedings of the 30th Annual Meeting of the American College of Veteri-
nary Ophthalmologists, Chicago, 1999. p. 73.

[92] Johnson SM. Neurotrophic corneal defects after diode laser cycloablation. Am J

Ophthalmol 1998;126(5):725–7.

[93] Quinn RF, Parkinson K, Wilcock B, et al. The eﬀects of continuous wave Nd:YAG and

semiconductor diode laser energy on the canine ciliary body: in vitro thermographic
analysis. Vet Comp Ophthalmol 1996;6(1):45–50.

[94] Cullen CL, Grahn BH. Equine glaucoma: a retrospective study of 13 cases presented at

the Western College of Veterinary Medicine from 1992–1999. Can Vet J 2000;41:470–80.

[95] Brinkman MC, Nasisse MP, Davidson MG, et al. Neodymium:YAG laser treatment of

iris bombe and pupillary block glaucoma. Prog Vet Comp Ophthalmol 1992;2(1):13–9.

[96] Nadelstein B, Davidson MG, Gilger BC. Pilot study on diode laser iridotomy in dogs. Vet

Comp Ophthalmol 1996;6(4):230–2.

[97] Peiﬀer RL, Nobles RD, Carter J, et al. Internal sclerostomy with a mechanical trephine

versus the neodymium:YAG laser in dogs. Ophthalmic Surg Lasers 1997;28(3):223–30.

[98] Dziezyc J. Cataract surgery. Vet Clin North Am Small Anim Pract 1990;20(3):737–54.
[99] Nasisse MP, Davidson MG, English RV, et al. Neodymium:YAG laser treatment of lens

extraction-induced pupillary opaciﬁcation in dogs. J Am Anim Hosp Assoc 1990;26:275–81.

[100] Gilger BC, Davidson MG, Nadelstein B, et al. Neodymium:yttrium-aluminum-garnet

laser treatment of cystic granula iridica in horses: eight cases (1988–1996). J Am Vet Med
Assoc 1997;211(3):341–43.

[101] Nasisse MP, Davidson MG, Olivero DK, et al. Neodymium:YAG laser treatment of

primary canine intraocular tumors. Prog Vet Comp Ophthalmol 1993;3(4):152–7.

[102] Cook CS, Wilkie DA. Treatment of presumed iris melanoma in dogs by diode laser

photocoagulation: 23 cases. Vet Ophthalmol 1999;2(4):217–25.

[103] Vainisi SJ, Peyman GA, Wolf ED, et al. Treatment of serous retinal detachments associ-

ated with optic disk pits in dogs. J Am Vet Med Assoc 1989;195(9):1233–6.

[104] Vainisi SJ, Packo KH. Management of giant retinal tears in dogs. J Am Vet Med Assoc

1995;206(4):491–5.

[105] Sullivan TC. Surgery for retinal detachment. Vet Clin North Am Small Anim Pract

1997;27(5):1193–214.

[106] Sullivan TC, Davidson MG, Nasisse MP, et al. Canine retinopexy—a determination of

surgical landmarks, and a comparison of cryoapplication and diode laser methods. Vet
Comp Ophthalmol 1997;7(2):89–95.

[107] Pizzirani S, Gilger BC, Davidson MG. Transpupillary diode laser retinopexy in dogs.

Ophthalmoscopic, ﬂuorangiographic, and histopathologic study. In: Proceedings of the
30th Annual Meeting of the American College of Veterinary Ophthalmologists, Chicago;
1999. p. 47.

[108] University of Waterloo Safety Oﬃce. Laser Hazards Web site. Available at: http//www.

adm.uwaterloo.ca/infohs/lasermanual/documents/section6.html. Accessed May 10, 2001.

[109] Bader O, Lui H. Laser safety and the eye: hidden hazards and practical pearls. Presented

at the American Academy of Dermatology Annual Meeting Poster Session, Washington,
DC, February 1996. Available at: http://www.dermatology.org/laser/eyesafety.html.
Accessed May 10, 2001.

[110] United States Pharmacopeial Convention Web site. Available at: http://www.usp.org/

reporting/prnews/dsw_092.htm. Accessed June 10, 2001.

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Laser use in veterinary dentistry

Jan Bellows, DVM

Hometown Animal Hospital and Dental Clinic, Weston, FL 33326, USA

Lasers used for oral procedures

Argon lasers (488 to 514 nm)

The argon laser’s wavelengths operate in the blue-green region and are

absorbed strongly by hemoglobin, which allows the laser energy to cut,
vaporize, or coagulate most types of oral tissue. Dental argon lasers are low
power devices (5 W or less). Fibers must be used in a contact mode or near-
contact mode to cut or vaporize oral tissue. Power output of 2.5 W and a
spot size of 2.0 mm are used for small (<2 mm) lesions.

Argon dental lasers are used for gingival surgery, curing of dental com-

posites during tooth restoration, and in human dentistry for tooth whiten-
ing. The main argon laser wavelengths at which most of the blue-green
output power is provided are 488 and 514 nm. Argon lasers are either used
in continuous wave (CW) or single pulse mode [1].

Argon laser wavelengths penetrate up to several millimeters into hard den-

tal surfaces. Consequently, there are potential risks of direct laser injury to the
tooth pulp. The use of argon lasers for hard tissue applications, such as bone
and teeth, is limited by their weak absorption in dental hard tissue. Argon
lasers may prove useful for enamel surface modiﬁcation for surface heat treat-
ment (enamel melting and resolidiﬁcation) for small enamel defects [2].

Carbon dioxide lasers (10,600 nm)

Carbon dioxide (CO

) lasers are used in oral surgery for precisely cutting

or vaporizing soft tissue with hemostasis. CO

lasers intended for dental

applications are CW lasers (Fig. 1). The CO

wavelength is absorbed by the

water content of oral tissues. Thermal necrosis zones of 100 to 300 lm at cut
tissue edges are typical, providing better oral structure safety compared with
other lasers (neodymium:yttrium aluminum garnet [Nd:YAG], argon, and

Vet Clin Small Anim 32 (2002) 673–692

E-mail address: dentalvet@aol.com (J. Bellows).

0195-5616/02/$ - see front matter

PII: S 0 1 9 5 - 5 6 1 6 ( 0 2 ) 0 0 0 1 0 - 4

diode), which may penetrate up to several millimeters. With the CO

laser,

‘‘what you see is what you get’’ compared with the Nd:YAG laser where
no immediately visible change appears in the tissue surrounding the zone of
vaporization. With the Nd:YAG laser, it is diﬃcult to estimate the true extend
of thermal necrosis. This advantage of replacing traditional excisional tech-
niques with CO

laser ablation permits removal of the damaged epithelium

with as little as 0.1 to 0.2 mm of reversible thermal injury to the submucosa.

lasers are used for oral, soft tissue procedures, such as gingivectomy,

gingivoplasty, frenectomy, and biopsy. Tissue vaporization is more eﬃcient
with the CO

laser than with the other lasers discussed because of the direct

absorption of this wavelength by water. Inorganic components of teeth and

Fig. 1. CO

laser (AccuVet Carbon Dioxide Laser, Lumenis, Inc., Santa Clara, CA).

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J. Bellows / Vet Clin Small Anim 32 (2002) 673–692

bone also absorb at the CO

wavelength. High temperatures (>100

°C) are

required to truly vaporize hard tissue. CW CO

lasers cannot ablate or cut

calciﬁed tissue without inducing severe charring and thermal injury to sur-
rounding tissue [1].

Modes used for dental applications include CW and variations of the

pulsed mode. For oral lesion ablation, the superpulse mode is the most
desirable because the pulse width is shorter than the thermal relaxation time
of oral soft tissue, thus decreasing the region of lateral thermal damage. For
oral lesion ablation, laser power is set between 10 and 15 W in CW mode or
20 W in a pulsed mode (Accuvet NovaPulse Carbon Dioxide Laser, Lume-
nis, Santa Clara, CA). The laser beam spot size will vary between 2 and 3 mm
in diameter. The lesion is outlined with a suitable margin of several
millimeters (Fig. 2A) Using paint brushstrokes, multiple applications of the
laser are then placed within the marginal outline. This technique is called

Fig. 2. (A) CO

laser-circumscribed tongue lesion. (B) Oral lesion ablated through ‘‘rastering.’’

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J. Bellows / Vet Clin Small Anim 32 (2002) 673–692

‘‘rastering’’ (Fig. 2B). After completing the ﬁrst ablation layer, there should
be almost no carbonization. If the wound appears blackened or charred,
there has been excessive heat conduction because of prolonged contact
between the laser beam and the tissue resulting from an excessively slow
hand speed in moving the handpiece across the lesion (Fig. 3).

A moistened gauze is used to wipe away the treated area of mucosa to

assess the depth of laser penetration. A pale pink base that does not bleed
indicates removal of the epithelium to the level of the basement membrane.
Several areas of rastering may be required. The submucosal layer is identi-
ﬁed by both appearance of blood vessels and a ‘‘yellow-looking’’ granular
tissue layer. Within 24 hours, a ﬁbrin coagulum forms on the surface of sur-

Fig. 3. Char as a result of excessive laser power or prolonged ‘‘on’’ time.

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J. Bellows / Vet Clin Small Anim 32 (2002) 673–692

gical wounds, which acts as a bandage. The coagulum is progressively
replaced by epithelium originating from the wound edge. Ablation of less
than 2.0 cm of mucosa results in complete epithelial resurfacing in less than
3 weeks, unless a charred layer is left, which retards healing.

To use the CO

laser as a precise cutting instrument for oral surgery, the

laser beam spot size at its focal point should be 0.2 to 0.3 mm. Traction and
countertraction of tissue with surgical sponges and tissue forceps facilitate
precise incisional and ablative laser surgical technique (Fig. 4).

Semiconductor diode lasers (805 to 980 nm)

Diode lasers in the 800 to 980 nm range are used with hot-tipped contact

mode optical ﬁbers for cutting or vaporization of oral tissue. Diode units are
similar in advantages and disadvantages to Nd:YAG lasers. The diode laser
penetrates deeply (1 to 2 mm) into most types of hard and soft dental tissues.
Diode dental lasers are used for gingivectomy, gingival troughing, subgingi-
val curettage, and other soft tissue procedures.

Diode and Nd:YAG laser radiation penetrates deeper than either CO

argon wavelengths. For oral surgery, changes in tissue texture and color
are best indicators of laser eﬀect. Frequent water irrigation is used as a ‘‘heat
sink’’ to decrease thermal damage when using the diode laser in the oral
cavity [3].

Before use in the oral cavity, a layer of ‘‘micro carbon’’ is prepared on the

contact tip. The carbon absorbs the laser beam, converting it into thermal
energy, which is then transferred to tissue. Diode laser contact applications
used in CW mode allow more precise tissue incisions with localized vapor-
ization. Beam penetration is typically limited to 0.5 mm, allowing for mini-
mal collateral photothermal damage. For contact incisional application,

Fig. 4. Traction placed on lesion during application of CO

laser energy allows more precise

and controlled dissection.

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J. Bellows / Vet Clin Small Anim 32 (2002) 673–692

mechanical pressure is unnecessary; only suﬃcient pressure to guide hand-
piece along the incision. Once the ﬁber is in contact mode, it needs to be kept
in contact mode or else it will degrade and fragment unless minimal (2 to 5 W)
power is used. The ﬁber can be used ﬁrst in noncontact (free beam) and then
placed in contact mode, but not vice versa.

Erbium lasers (2900 nm)

The erbium:neodymium:yttrium aluminum garnet (YAG) laser has

recently been approved by the US Food and Drug Administration for use
in dental hard tissue (Fig. 5). This laser operates by the process of light
absorption by water droplets. This laser can precisely cut or ablate hard den-
tal substances, including enamel with relatively little pulse energy and aver-
age power because the 2936 nm wavelength is absorbed by water, as well as
inorganic hydroxyapatite. Erbium lasers are not operated in continuous
mode fashion, but in a Q-switched noncontact mode to generate pulses of
about 100 nsec in duration. The handpiece is held approximately 2 cm from
the targeted tissue site.

Incisions made in soft tissue with an erbium laser heal almost as quickly

as scalpel incisions. Because little collateral thermal injury is produced, very
little hemostasis occurs [4].

Holmium lasers (2100 nm)

Holmium lasers can cut and vaporize soft tissue similar to the CO

laser

but with the added advantages of energy delivery through ﬂexible quartz
optical ﬁbers. The holmium laser can also precisely ablate hard materials,
such as bone, dentin, and enamel. Because of the holmium laser’s engineer-
ing characteristics, pulsed modes with 250 to 350 msec duration must be

Fig. 5. Erbium:YAG dental laser (Biolase Technology, San Clemente, CA).

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used, which imparts some photomechanical eﬀect on tissue. Holmium lasers
are used in dental surgery for both contact cutting and vaporization or for
noncontact vaporization and tissue coagulation. Thin ﬂexible ﬁbers can also
be used to thoroughly debride pulp from root canals with or without dentin
removal.

Nd:YAG lasers (1064 nm)

The Nd:YAG laser penetrates deeply (several millimeters) into oral soft

tissues. Energy penetrates tissue until it is absorbed by the ﬁrst heavy pig-
ment it encounters. There is little absorption by water, moderate absorption
for hemoglobin, and high absorption for melanin. This highly energetic
beam presents potential risk of thermal injury to pulp, periodontal ligament,
and bone when working on or near teeth. The Nd:YAG laser may be used in
CW mode or in single pulse, repeat pulse, and Q-switched emission modes.
In human dentistry, low-power Nd:YAG lasers are used to provide laser
induced analgesia to teeth without local anesthesia. For oral mass ablation
in human dentistry, a large volume of tissue destruction can be accom-
plished using the Nd:YAG laser. Tissue welding (apposition of incised gin-
gival tissues without sutures) has been clinically performed in human
dentistry using low power (0.1 to 1.0 W) [5].

General laser concepts as they apply to veterinary dentistry

Laser safety considerations when dealing with the oral cavity

All lasers in the dental operating area have the potential to ignite materi-

als on and around the surgical site. Examples of combustible materials
include dry cotton swabs, gauze sponges, wooden tongue blades, alcohol
wipes, and plastic instruments.

The greatest ﬁre danger in laser surgery of the oral cavity is the endotra-

cheal tube. Special care must be taken to prevent the tube from coming in
contact with the laser during surgery because ignition of the endotracheal
tube produces a ﬁre with a blowtorch eﬀect inside the animal’s airway.
Laser-safe endotracheal tubes are available for use during laser surgery.

In addition, to avoid laser damage, premoistened gauze is packed in the

pharyngeal area. They serve as additional protection for the endotracheal
tube by absorbing laser light and ensuring greater protection for patients.

The plume or lased smoke is a byproduct of laser surgery. The laser

plume is primarily composed of vaporized water (steam), carbon particles,
and cellular products. This smoke is irritating to those who come in contact
with it. Laser smoke contains toxic substances, such as formaldehyde, hydro-
gen cyanide, and hydrocarbons. A high-volume laser smoke evacuator is used
to remove the plume during oral procedures, especially if an endotracheal
tube is not being used.

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Lasers as bloodless scalpels in oral surgery

Lasers can be used to resect, dissect, excise, incise, or amputate oral tis-

sues, just as one would use a scalpel. One important diﬀerence is that hemo-
stasis can be provided, depending on the type of laser used and tissue
operated upon. Bleeding is only reduced in some cases rather than prevented
altogether (Fig. 6A,B).

The cutting action also depends on the type of laser and tissue. Generally,

lasers operated in continuous mode cut comparably to a scalpel, whereas
those lower pulsed modes (10 to 20 pulses/s) produce much slower or rougher
cutting action. Diode lasers used in contact mode often drag when making
oral incisions.

Laser vaporization

Laser vaporization is the process of removing solid tissue by converting it

to a gaseous vapor, usually in the form of steam or smoke, and then aspirating
away the smoke with an appropriate suction device. Complete vaporization
of hard substances, such as bone and tooth enamel containing hydroxyapatite
and other inorganic substances, requires heating of the inorganic component
to temperatures higher than 100

°C to convert it into a gaseous state.

Surgical precision in oral surgical procedures

The veterinarian using a laser in the oral cavity must be concerned with

possible damage to sensitive oral structures, including tooth pulp, periodon-
tal ligament, and bone. The actual zone of damage that can be tolerated
depends on the proximity and sensitivity of nearby oral structures. Because
tooth pulp and periodontal ligament are thought to be very sensitive to ther-
mal injury, they can tolerable no more than a few degrees centigrade rise in
temperature for even a short period.

Speciﬁc veterinary dental procedures

Gingivoplasty and gingivectomy

The CO

laser is a versatile laser for precisely cutting or vaporizing the gin-

giva. Higher CO

laser power (10 to 20 W) are used to remove moderate

amounts of hyperplastic gingiva. The CO

laser may also be used in a defo-

cused or diverging mode (increase laser beam spot size/decrease power den-
sity) for coagulation to help control bleeding after scalpel blade gingivectomy.

Oral biopsy

Generally, lasers can be used for excisional or incisional biopsies with bet-

ter control of bleeding and improved visualization. Controlled laser excision

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Fig. 6. (A) Large malignant melanoma lesion on tongue. (B) Lesion clinically excised with
minimal blood loss using a CO

laser.

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permits histologic evaluation and establishment of clean margins. A pathol-
ogist knowledgeable regarding laser–tissue interaction should be able to
examine the margins of the specimen more accurately because the laser
destroys tissue in a more precise manner, causing a central zone of tissue
vaporization and only 100 to 200 lm of tissue necrosis adjacent to the point
of impact. This is especially true when using the CO

laser (Fig. 7).

Because the CO

laser can cut soft tissue in a noncontact mode, it is par-

ticularly useful for biopsy on buccal and lingual surfaces. An excisional out-
line is made rapidly using repeated single pulses (5 W, 0.3-mm spot size,
NovaPulse Carbon Dioxide Laser) to circumscribe the desired target tissue.
After producing this outline, one edge of the incised margin can be elevated

Fig. 7. Benign mass outlined with CO

laser beam before excision.

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with forceps, and the lesion can be undermined and harvested at the correct
depth of dissection with the laser. With the laser beam defocused, the surgi-
cal wound is briskly ‘‘painted’’ over in one pass to seal oﬀ lymphatics, blood
vessels, and nerve endings. Sutures are frequently not required unless the
defect is larger than 8 mm. Argon, Nd:YAG, and diode lasers are all used
for biopsies.

Gingival troughing for crown preparation

When preparing a tooth for crown restoration, a trough or space between

the marginal gingiva and crown is created to allow for a marginal line and
impression material. If made with a scalpel blade, the incised gingiva bleeds,
generating additional surgical time for hemostasis. CO

and diode lasers are

used for gingival troughing. Considering the proximity of the tooth during
troughing, one must worry about possible inadvertent laser injury. Proper
tooth shielding is required for protection. Argon lasers are not recom-
mended because their wavelength is strongly absorbed by blood (Figs. 8,9).

Operculectomy (removal of gingival tissue over an impacted tooth)

Lasers are used to remove soft tissue during operculectomy with little or

no postoperative swelling or bleeding common in conventional excision
techniques. Excision technique is preferred, compared with vaporization
of the overlying gingiva. Ten watts with 0.3-mm spot size (NovaPulse Car-
bon Dioxide Laser) is used to incise around the impacted crown. As dissec-
tion proceeds, the mucosal ﬂap is elevated with tissue forceps until the
underlying crown is identiﬁed. Alternatively, the Nd:YAG laser in contact
mode is used at 5 to 10 W to excise the gingival cuﬀ.

Frenectomy

Lasers are used to perform maxillary and lingual frenectomies with little

or no bleeding and often without the need for sutures. When used in a non-
contact mode, the CO

laser vaporizes frenums quickly. The NovaPulse

Carbon Dioxide Laser is used in CW mode at 3 to 5 W with a 0.3-mm spot
size for incision or in pulsed mode at 20 W and a 1.4-mm spot for ablation.
With the frenum stretched taut, a short vertical incision is made through the
mucosa at the midportion of the frenum. Horizontal-releasing incisions are
then developed through the mucosa on both sides of the frenum, which may
extend to the periosteum (Fig. 10).

Solitary tongue lesions

Often, the patient presents with solitary benign lesions arising from the

dorsal anterior tongue. The lesion can be bloodlessly removed quickly using
the CO

laser (NovaPulse Carbon Dioxide Laser) at 10 W and with a 0.3-mm

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Fig. 8. (A) Palatal appearance of fractured right central and intermediate incisors after root
canal therapy and access restoration. (B) CO

laser used to ‘‘trough’’ or deepen gingiva

surrounding the aﬀected teeth before crown preparation. (C) Prepared crowns after
cementation.

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Fig. 9. (A) Fractured maxillary canine, with fracture extending below the gingival margin. CO

laser used for gingivectomy for crown elongation procedure. (B) Healing gingiva before crown
cementation. (C) Crown cementation.

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Fig. 10. (A) Clinical absence of left mandibular ﬁrst premolar. (B) Radiograph revealing
partially erupted premolar. (C) Operculectomy removing gingiva to reveal underlying ﬁrst
premolar.

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spot/tip size. Avoid penetration into the muscularis layer. Sutures are gener-
ally placed if the postsurgical defect is larger than 3 mm.

Transoral resection of oral cancer

Laser use in oral cancer surgery provides better hemostasis, less post-

operative edema, and diminished infection. In addition, there is a reduced
likelihood of inducing tumor microemboli during the procedure because
of the laser’s ability to seal small blood vessels and lymphatics.

Both the CO

and Nd:YAG lasers are used in resection of oral cancer.

When using the CO

laser (NovaPulse Carbon Dioxide Laser), 15 to 20 W

are used with a 0.3-mm spot size to facilitate dissection of the mass until an
adequate margin is established. The advantage of using the Nd:YAG laser
rather than the CO

laser is increased hemostasis.

Fig. 11. (A) Canine oral squamous cell carcinoma. (B) CO

laser used periodically over an

18-month period to debulk the tumor for palliative care.

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Palliative treatment for nonresectable masses can be accomplished using

the laser to debulk the mass before radiation therapy or to periodically
decrease the tumor size to make the patient more comfortable (Fig. 11).

Gingival surgery

Gingivoplasty is performed in cases of minimal lingually displaced canine

teeth to remove gingival areas of mandibular canine tooth penetration. For
the gingivoplasty, 8 to 10 W of superpulsed CO

laser (NovaPulse Carbon

Dioxide Laser) energy in a defocused mode is used to remove sequential
layers of tissue until the mandibular canine tooth is no longer impinging
on the gingiva. This is only performed in mild cases (Fig. 12).

Interdental incisions for periodontal ﬂap surgery can be performed with

the diode or CO

laser. Human patients reported less pain with laser surgery

compared with the opposite side where scalpel blade ﬂap incisions were
made [6] (Fig. 13).

In cases of gingival hyperplasia, the laser can be used after blade gingi-

vectomy to shape gingiva and to aid in hemostasis. The CO

laser can be

used at 4 to 8 W in CW mode with light feather-like strokes over the incised
area, which results in a light char layer (Fig. 14).

Fig. 12. (A) Right mandibular canine tooth impinging on maxillary gingiva. (B) CO

laser gin-

givoplasty. (C) Palatal penetration removed.

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Removal of sublingual tissue folds (gum chewer’s lesions) can also be

accomplished using the CO

laser. After excision, decrease the laser power

to 4 W and ‘‘defocus’’ the beam to vaporize the excised tissue areas and
to seal small blood vessels. Sutures are not usually needed.

Feline stomatitis therapy

Feline stomatitis (lymphocytic plasmacytic gingivostomatitis) is a multi-

factorial disease. Lasers are used to vaporize areas of clinical inﬂammation
and may be helpful as an adjunct to treatment. Preoperative blood testing (in-
cluding screens for feline immunodeﬁciency virus and feline leukemia virus)
and full mouth intraoral dental radiographs are performed and evaluated.
Therapy then consists of extraction of those teeth that have feline odonto-
clastic resorptive lesions or that have more than 25% alveolar bone loss.

The CO

laser can be used at 6 W in a CW mode or in the superpulse

mode at 4 to 6 W to vaporize inﬂamed tissue and ﬁstulous tracts. Vaporiza-
tion is accompanied with plume evacuation, and moistened gauze is used to
wipe away char. The beam is ‘‘defocused’’ to ‘‘paint’’ the entire inﬂamed tis-
sue area. Repeat the process until there is minimal bleeding after the char is
wiped away (Fig. 15).

Fig. 13. (A) Gingival incisions for ﬂap surgery to expose feline canine tooth root fragment.
(B) Flap reﬂected exposing lateral alveolar plate. (C) Root fragment exposed after lateral
alveolus is removed.

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Fig. 14. (A) Marked gingival hyperplasia. (B) CO

laser used for coagulation after tissue re-

moval with scalpel. (C) Healed tissue 1 month postoperative.

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There may be some beneﬁt in using a CO

scanner or pattern generator

for beam delivery. The scanner improves tissue vaporization over a large
area and reduces heat accumulation in tissue during ablation.

Postoperatively, clindamycin (5 mg/lb/d orally) is given for 2 weeks.

Depending on degree of inﬂammation and patient condition, prednisone
(1 mg/lb orally) is administered daily in a decreasing dosage regimen over
a 10-day period. Monthly follow-ups are advised. Depending on response,
repeat laser treatments are performed to remove residual inﬂammation.
Often, nonresponsive cases need additional extractions.

Future applications

As veterinarians are becoming more comfortable with the use of lasers in

the oral cavity, similar applications in human laser dentistry will be used in
veterinary patients. Some uses under investigation include etching enamel
and dentin for bonding. Preliminary studies show a better etch may be
obtained with the laser than with conventional phosphoric acid. In addition,
laser treatment may improve marginal sealing and decrease microleakage of
composite resin restorations.

Fig. 15. (A) Severe faucitis causd by lymphocytic plasmacytic stomatitis syndrome. (B) CO

laser used to vaporize inﬂamed tissue after extraction of all teeth distal to the canines.
(C) Lesions completely healed after two additional monthly laser treatments.

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Lasers may also be used to fuse dentin in the root canal, creating an api-

cal plug of glazed nonporous material, which is free of organic tissues.
Endodontic disinfection and coagulation for vital pulpotomy may become
preferred over the use of calcium hydroxide to create a dentinal bridge.

Ongoing research into laser use in feline odontoclastic resorptive lesions

(FORLs) will conﬁrm if the use of lasers eﬀectively destroys surface odonto-
clasts to control class 1 and 2 lesions and to desensitize exposed dentin. A
recent article reported the use of a Nd:YAG laser for the treatment of
FORLs [7]. Unfortunately, until we ﬁnd out the true cause of these lesions,
destroying surface odontoclasts may help control the disease but will not
treat its etiology or provide a cure.

Lasers may also be helpful for periodontal tissue regeneration in furca-

tion areas by vaporizing inﬂamed tissues and by stimulating wound healing.

References

[1] Featherstone JDB, Nelson DGA. Laser eﬀects on dental hard tissues. Adv Dent Res 1987;

1:21–6.

[2] Kelsey WP, Blankenau R, Powell GL. Application of the argon laser to dentistry. Lasers

Surg Med 1991;11:495–8.

[3] Montaheni DM, Lasers in dentoalveolar surgery. In: Oral and Maxillofacial Surgery

Knowledge Update. Alpharetta (GA): American Association of Oral and Maxillofacial
Surgeons; 1995. p. 59–64.

[4] Gimbel CB. Hard tissue laser procedures. In: Convissar RA, editor. Lasers and light

ampliﬁcation Philadelphia: W.B. Saunders; 2000. p. 931–54. Dent Clin North Am 44(4):

[5] Nagasawa A. Nd:YAG laser therapy in dental and oral surgery. In: Joﬀe SN, Oguro Y,

editors. Advances in Nd:YAG laser surgery. New York: Springer-Verlag; 1988. p. 235–46.

[6] Meyers TD. The future of lasers in dentistry. In: Convissar RA, editor. Lasers and light

ampliﬁcation. Philadelphia: W.B. Saunders; 2000. p. 971–80. Dent Clin North Am 44(4):

[7] Anthony J. The use of a Nd:YAG laser for treatment of feline osteoclastic resorptive lesions.

J Am Anim Hosp Assoc 2001;37:17–19.

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J. Bellows / Vet Clin Small Anim 32 (2002) 673–692

Photodynamic therapy for companion

animals with cancer

Michael D. Lucroy, DVM, MS

Department of Veterinary Clinical Sciences, 001 Boren Veterinary Medical Teaching Hospital,

College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA

Photodynamic therapy (PDT) is a US Food and Drug Administration

(FDA)-approved treatment for various human esophageal and endobron-
chial cancers [1,2]. PDT involves the administration of a tumor-localizing
photosensitizer (PS), either topically, orally, or intravenously, followed by
light activation. PDT is also known as photochemotherapy or light-activated
chemotherapy and is a highly selective form of cancer therapy when com-
pared with radiation therapy or systemic chemotherapy. If not activated, the
PS is not harmful to tissue; likewise, the low level of light energy used during
PDT is, alone, not suﬃcient to damage tissue. PDT-mediated tissue damage
requires the simultaneous presence of the PS, light of an appropriate wave-
length, and molecular oxygen (Fig. 1) [3]. At present, PDT is considered an
investigational cancer treatment in veterinary medicine. The results from
treating companion animals with spontaneous tumors have been recently
reviewed [4,5].

History of PDT

One of the earliest references to light therapy comes from ancient India

around 1400

, where various plant seeds and sunlight were used to treat

vitiligo [6]. Likewise, ancient Egyptians used plant seeds and sunlight to
treat leukoderma. In modern times, light therapy for vitiligo and leukoderma
remains virtually unchanged, relying on puriﬁed psoralen from plant seeds
and artiﬁcial ultraviolet radiation (UV; 320 to 400 nm) [7].

The ﬁrst scientiﬁc report of a biologic photodynamic reaction came late in

the nineteenth century, when the light-enhanced toxicity of quinine to frog
eggs and various plants was described [8]. The medical potential for these
light-mediated reactions was not realized, however, until the early twentieth

Vet Clin Small Anim 32 (2002) 693–702

E-mail address: lucroy@okstate.edu (M.D. Lucroy).

0195-5616/02/$ - see front matter

PII: S 0 1 9 5 - 5 6 1 6 ( 0 2 ) 0 0 0 1 1 - 6

century when PDT began to emerge as a science. In 1903 the Nobel Prize was
awarded to Dr. Niels Finsen for his research studying eosin and light as a
treatment for lupus vulgaris [6]. Later that year, the term ‘‘photodynamic
therapy’’ was coined, when the discovery was made that oxygen was a neces-
sary component for favorable photochemical reactions [9]. During the fol-
lowing decade, the photosensitizing properties of various porphyrins,
including hematoporphyrin a precursor of modern PS, were studied [10,11].

In the late 1940s and early 1950s, PDT researchers discovered that hema-

toporphyrin preferentially accumulated in murine tumors and that the ﬂuo-
rescence of hematoporphyrin derivative could be used to detect tumors
[12,13]. In the 1970s, the ﬁrst human cancers were treated with PDT, produ-
cing convincing results [14,15]. At the same time, PDT-mediated cytotoxicity
was determined to be partly caused by singlet oxygen formation [16]. Also
during this time, the introduction of a ﬁberoptic delivery system coupled
to a tunable argon-pumped dye laser facilitated PDT research by providing
large quantities of monochromatic light at varying wavelengths [17].

The earliest reports of PDT for domestic animals with spontaneous

tumors occurred in the early 1980s when dogs and cat were injected with
hematoporphyrin and irradiated with a laser [18,19]. Although these studies
included dogs and cats with a variety of tumor types, most tumors were con-
sidered responsive, thus showing the clinical potential of PDT for treating
solid tumors. The early veterinary studies were contemporary with the ﬁrst
human clinical trials of PDT [20,21]. From this point forward, investigations
of porphyrin derivatives and newer generation PS have rapidly increased,
opening the myriad possibilities for clinical PDT applications. During the
past three decades, thousands of human patients have undergone PDT,
whereas comparatively few veterinary patients have received PDT [5].

Fig. 1. Schematic depiction of the events involved in PDT. Tumor destruction requires the simul-
taneous presence of the photosensitizer (PS), light of the appropriate wavelength, and molecular
oxygen (O

). Tumor death may occur as a result of direct oxidative damage, ischemia, or non-

speciﬁc inﬂammatory cell killing.

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Ideal PS

The number of new PSs currently being developed for clinical use is an

indication that the ideal PS is not yet available. The properties of the ideal
PS should include no systemic toxicity, selective uptake and retention by
tumor tissue, eﬃcient generation of oxygen radicals using light wavelengths
readily transmitted through tissue, and rapid clearance from the skin [22].
One major concern for PS development is prolonged cutaneous photosensiti-
zation. As an example, porﬁmer sodium (Photofrin), the ﬁrst FDA-approved
PS for humans, may cause severe cutaneous photosensitization for as long
as 8 weeks after administration [2]. Many PSs have been evaluated for com-
panion animals with cancer, including porﬁmer sodium, 5-aminolevulinic
acid (Levulan), metatetrahydroxyphenylchlorin (Foscan), pheophorbide-a-
hexylether (Photochlor, HPPH), aluminum phthalocyanine tetrasulfonate
(AlPcS

), and 5-ethylamino-9-diethylaminobenzo[a]phenothiazinium chlo-

ride (EtNBS) [5].

PS localization

As previously mentioned, PDT involves the systemic administration of a

PS, which must selectively localize in neoplastic tissue. The increased tumor-
to-normal tissue ratio of PS concentration is one reason why PDT selec-
tively kills cancer cells. Although the exact mechanisms of PS tumor locali-
zation remain unclear, tumor characteristics, drug delivery vehicle, and PS
may all play a role. Tumor factors that contribute to the retention of PS
include a large interstitial space, leaky vasculature, acidic pH, high lipid con-
tent, copious newly synthesized collagen, presence of macrophages, and in-
creased numbers of low-density lipoprotein receptors [2]. When compared
with normal surrounding tissue, acidic tumor pH increases lipophilicity and
therefore cellular uptake of PS [23]. Intratumoral lipid binds lipophilic PS,
and porphyrins have an aﬃnity for newly formed collagen [24,25]. Tissue
macrophages ingesting large amounts of certain PS may deliver it to the
tumor [26,27]. Increasing PS hydrophobicity by augmentation with lipo-
some delivery systems enhances tumor localization [28,29]. Preferential PS
release to tumor cells can also be achieved by associating the PS with
low-density lipoproteins [30,31]. At present, the relative importance of these
observations for PS localization within tumors is unknown.

Light delivery

As previously mentioned, the development of medical lasers in the latter

half of the twentieth century presented PDT researchers with tools capable
of delivering tremendous amounts of monochromatic light. Unfortunately,
the paradigm that lasers are required for PDT has probably slowed its wide

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acceptance in human medicine and has limited the use of veterinary PDT to
academic institutions and research facilities. The dye laser, which is tunable
over a wide range of visible wavelengths, was used for early PDT studies.
Although well suited for PDT research with multiple photosensitizer activated
at varying wavelengths, tunable dye lasers are not well suited for routine veter-
inary use because of their physical size, initial and ongoing expenses, and
requirement for specialized electrical or plumbing connections. In our facility,
a pulsed KTP-pumped dye laser (Laserscope, San Jose, CA) is used for most
clinical treatments (Fig. 2). These pulsed KTP lasers with dye module require
considerable space in the operating theater, and the pulsed KTP laser requires
a three-phase, 220-V, 60-amp electrical connection. Several manufacturers
now oﬀer market portable, air-cooled, single wavelength, diode lasers with
suﬃcient power output for clinical PDT; however, these lasers still cost tens
of thousands of dollars. The authors are presently using a 635-nm diode laser
(CeramOptec, Longmeadow, MA) for selected clinical PDT treatments (Fig. 2).

Nonlaser light sources (eg, ﬁltered lamps) for PDT are becoming avail-

able. These light sources are much less expensive than medical lasers and
have fewer associated eye safety issues. The authors are currently investigat-
ing a ﬁltered lamp (LumaCare, Ci-Tek, London, UK) with ﬁve diﬀerent
wavelength bands for veterinary PDT use (Fig. 2). In a limited number of
cases, the authors have observed comparable initial results using the non-
laser light source; however, the light treatment times are much longer than
with a laser light source. Safe and inexpensive light sources are requisite for
the widespread application of PDT in veterinary medicine.

The choice of photosensitizer dictates which wavelength of light is required

for treatment. For example, porﬁmer sodium is activated at 630 nm, whereas
pheophorbide-a-hexylether is activated at 665 nm, and aluminum phthalocya-
nine tetrasulfonate (AlPcS

) is activated at 675 nm. Light wavelength is

directly proportional to tissue penetration, with light of more than 630 nm
(ie, visible red light) being transmitted easily through tissues and therefore
being well suited for PDT [32,33]. Light is delivered to the target tissue through
surface, interstitial, or intraoperative irradiation. During surface irradiation,
light from an optical ﬁber terminating in a microlens is focused on the tumor.
Optical ﬁbers terminating in cylindric diﬀusers are placed directly into tumors
for interstitial irradiation (Fig. 3). Special optical ﬁbers designed for use with
ﬂexible endoscopes are used to irradiate esophageal and endobronchial can-
cers. Because these optical ﬁbers are small (from 200 to 1000 lm in diameter),
virtually any site is accessible for ﬁber placement.

Light dosimetry

Light dosimetry is expressed as the amount of light (ie, number of photons)

delivered to a given area and the rate at which the light is delivered [34–36].
Fluence refers to the light dose and is expressed as joules per square centimeter

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M.D. Lucroy / Vet Clin Small Anim 32 (2002) 693–702

Fig. 2. Various light sources used for PDT. (A) A pulsed KTP-pumped dye laser. (B) A solid-
state diode laser. (C) A ﬁltered lamp with metal clad-bundled optical ﬁber cable.

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M.D. Lucroy / Vet Clin Small Anim 32 (2002) 693–702

(J/cm

). The power density refers to the rate of delivery and is expressed as

watts per square centimeter (W/cm

). The treatment time (in seconds) is cal-

culated using the formula: T

¼ J/cm

W/cm

. The required light output is

calculated using the formula: P

¼ A · W/cm

, where P is the power in watts,

and A is the surface area to be treated. Measuring light energy requires the use
of a thermopile power meter or an integrating sphere power meter, depending
on the type of output device (eg, microlens and cylindrical diﬀuser).

Fluence and power density aﬀect PDT eﬃcacy. As power densities exceed

0.125 W/cm

, the treated tissue is heated, thereby making it impossible to

discern hyperthermia eﬀects from PDT eﬀects [37,38]. PDT using low-power
densities results in eﬃcient tumor killing [39,40]; however, this requires long
treatment times. For example, a PDT session using a power density of 0.04
W/cm

and a ﬂuence of 200 J/cm

requires 84 minutes to complete. Alternat-

ing light and dark intervals also increases PDT eﬃcacy [39,40]. The optimal
light and dark intervals and power densities have not yet been established,
however, for clinical PDT.

PS activation

There is no eﬀect on the tumor until the PS is activated by light of the ap-

propriate wavelength. This selectivity of action spares the patient the potential
adverse eﬀects of systemic chemotherapy and, unlike radiation therapy, only

Fig. 3. Optical ﬁbers used with a laser for PDT of cancer. An optical ﬁber terminating in a
microlens (left), and an optical ﬁber terminating in a cylindrical diﬀuser (right).

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M.D. Lucroy / Vet Clin Small Anim 32 (2002) 693–702

aﬀects the volume of tissue illuminated with light. The PS absorbs photons,
which raises its energy state to the excited singlet or triplet state [41,42].
Once activated, the PS can interact with nearby molecules (type I reaction)
or with molecular oxygen (type II reaction). The resultant reactive oxygen
species and free radicals damage cellular structures, and cellular death
results if the damage exceeds the capacity of endogenous repair mechanisms
[16,41]. The rapid response to PDT observed in experimental tumors is
caused by several factors: (1) direct oxidative damage to tumor cells, (2) oxi-
dative damage to vasculature with resultant ischemic cell death, and (3) non-
speciﬁc cell killing by inﬂammatory cells [41,43–45]. Although unclear, the
role that each factor plays in PDT-mediated tumor death may be inﬂuenced
by PS localization within the tumor. Diﬀerences in PS localization have been
reported between carcinomas and sarcomas [46].

PDT indications

PDT is best suited for localized cancers that do not readily metastasize.

Perhaps the best-studied cancer treated with PDT in veterinary medicine is
squamous cell carcinoma (SCC). Facial SCC in cats has been treated with
both aluminum phthalocyanine tetrasulfonate- and pheophorbide-a-hexy-
lether–based PDT [47,48]. A complete response rate of 70% was reported
in 18 cats treated with AlPcS

-based PDT, and tumor progression-free inter-

vals were reported to be as long as 18 months [47]. Cutaneous photosensiti-
zation and hepatotoxicity were reported, however, in some of these cats.
Pheophorbide-a-hexylether–based PDT produced a 1-year local control rate
in 61 treated cats [48]. Furthermore, in cats with tumors smaller than 1.5 cm
in diameter, the complete response rate was 100%. A single pheophorbide-a-
hexylether–based PDT treatment for facial SCC in cats is just as eﬀective as a
fractionated course of external beam radiation therapy [49].

Oral SCC in 11 dogs was treated with pheophorbide-a-hexylether–based

PDT [50]. Eight of the 11 dogs were considered cured, with disease-free inter-
vals longer than 17 months. The long-term PDT results were similar to partial
maxillectomy or mandibulectomy for the treatment of canine oral SCC, even
when bony involvement was radiographically apparent. Other cancers in dog
and cats that reportedly respond to PDT include mast cell tumor, ﬁbrosar-
coma, hemangiopericytoma, basal cell tumor, and melanoma. In our hospi-
tal, the author is presently investigating the use of PDT for treating
transitional cell carcinoma of the urinary bladder and intranasal tumors.
Although long-term follow-up and case accrual is not complete, early results
are promising.

Potential uses

In addition to the treatment of cancer, PDT has several other potential

uses in veterinary medicine, including the elimination of the feline leukemia

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M.D. Lucroy / Vet Clin Small Anim 32 (2002) 693–702

retrovirus (FeLV) and FeLV-infected leukocytes from stored blood using
benzoporphyrin derivative and nonlaser light [51]. This system could poten-
tially be developed for sterilizing stored colostrum for both large and small
animals. The best PS and light dosimetry have not yet been worked out,
however, for these ﬂuid models.

PDT has also been shown to be eﬀective for killing cutaneous bacteria

and yeast [52], which portends its use for the management of deep pyoderma
and chronic otitis externa. Large areas of skin can be irradiated using optical
ﬁbers ﬁtted with diﬀusing lenses, and external ear canals can be irradiated
with optical ﬁbers terminating in cylindric diﬀusers. Because PS can be ad-
ministered topically or parenterally, there are several options for developing
a useful antimicrobial PDT protocol.

PDT is also eﬀective against neovascularization, as shown by the

response of humans with macular degeneration treated with PDT. Because
PDT can target blood vessels for destruction, it is possible that PDT might
be useful in treating proliferative diseases in veterinary medicine, such as
exuberant granulation tissue in horses. PDT may also play a role in cancer
prevention if used to treat premalignant lesions, such as actinic keratosis.

Conclusions

PDT is a rapidly emerging and highly selective form of cancer therapy.

Tissue damage only occurs when the PS, molecular oxygen, and light of the
appropriate wavelength are present simultaneously. PDT applications in
veterinary medicine are in their infancy. At present, limited data exist to sup-
port the eﬃcacious and safe use of PDT for cancer treatment in companion
animals. In addition, the lack of a suitable PS and cost-eﬀective light sources
are the current limiting factors preventing widespread application of PDT in
veterinary medicine. Furthermore, the limited numbers of treatment centers
currently providing PDT to veterinary patients suggest that it will be some
time before suﬃcient numbers of suitably trained practitioners are available
to provide PDT in the private practice setting. PDT may also develop into a
useful therapy for nonneoplastic diseases of companion animals.

References

[1] McCaughan JS Jr. Photodynamic therapy: a review. Drugs Aging 1999;15:49–68.
[2] Dougherty TJ, Gomer CJ, Henderson BW, et al. Photodynamic therapy. J Nat Cancer Inst

1998;90:889–905.

[3] Dougherty TJ. Photodynamic therapy. Photochem Photobiol 1993;58:895–900.
[4] Lucroy MD, Magne ML, Peavy GM, et al. Photodynamic therapy in veterinary medicine:

current status and implications for application in human disease. J Clin Laser Med Surg
1996;14:305–10.

[5] Lucroy MD, Edwards BF, Madewell BR. Veterinary photodynamic therapy. J Am Vet Med

Assoc 2000;11:1745–51.

700

M.D. Lucroy / Vet Clin Small Anim 32 (2002) 693–702

[6] Daniell MD, Hill JS. A history of photodynamic therapy. Aust N Z J Surg 1991;61:340–8.
[7] Bethea D, Fullmer B, Syed S, et al. Psoralen photobiology and photochemotherapy: 50

years of science and medicine. J Dermatol Sci 1999;19:78–88.

[8] Marcacci A. Sur l’action des alcaloides dans les regne vegetal et animal. Arch Ital Biol 1888;

9:2–4.

[9] Jesionek A, Tappeiner VH. Zer Behandlung der Hautcarcinomit mit ﬂuorescierenden

stoﬀen. Muench Med Wochneshr 1903;47:2042.

[10] Raab O. Ueber die Wirkung ﬂuorescierenden Stoﬀe auf Infusorien. Z Biol 1908;39:524–6.
[11] Hausman W. Die sensibilisierende wirkung des hematoporphyrins. Biochem Z 1911;30:276.
[12] Figge FH, Weiland GS, Mangianello LO. Cancer detection and therapy: aﬃnity of neo-

plastic embryonic and traumatized tissue for metalloporphyrins. Proc Soc Exp Biol Med
1948;68:181–8.

[13] Schwartz S, Winkleman JW, Lipson RL. Historical perspective. In: Dougherty TJ,

Henderson BW, editors. Photodynamic therapy. New York: Marcel Dekker; 1992. p. 1–15.

[14] Kelley JF, Snell ME. Hematoporphyrin derivative: a possible aid in the diagnosis and

therapy of carcinoma of the bladder. J Urol 1976;115:150–1.

[15] Dougherty TJ, Kaufman JE, Goldfarb A, et al. Photoradiation therapy for the treatment of

malignant tumors. Cancer Res 1978;38:2628–35.

[16] Weishaupt KR, Gomer CK, Dougherty TJ: Identiﬁcation of singlet oxygen as the cytotoxic

agent in photo-inactivation of a murine tumor. Cancer Res 1976;36:2326–9.

[17] Dougherty TJ, Thoma RF, Boyle BG. Photoradiation therapy of malignant tumors: role of

the laser. In: Pratesi R, Sacchi CA, editors. Lasers in photomedicine and photobiology.
New York: Springer-Verlag; 1980. p. 67–75.

[18] Dougherty TJ, Thoma RE, Boyle BG, et al. Interstitial photoirradiation therapy for

primary solid tumors in pet cats and dogs. Cancer Res 1981;41:401–4.

[19] Cheli R, Assis F, Mortellaro CM, et al. Hematoporphyrin derivative photochemotherapy

of spontaneous tumors: clinical results with optimized drug dose. Cancer Lett 1984;23:
61–6.

[20] Hayata Y, Kato H, Konaka C, et al. Hematoporphyrin derivative and laser photoirradia-

tion in the treatment of lung cancer. Chest 1982;81:269–77.

[21] Wile AG, Dahlman A, Burns RG, et al. Laser photoradiation therapy of cancer following

hematoporphyrin sensitization. Lasers Surg Med 1982;2:163–8.

[22] Allison BA, Pritchard PH, Hsiang YN, et al. Low density lipoprotein as a delivery vehicle

in various applications of photodynamic therapy. Clin Invest Med 1993;16:B9.

[23] Barrett AJ, Kennedy JC, Jones RA, et al. The eﬀect of tissue and cellular pH on the selective

biodistribution of porphyrins-type photochemotherapeutic agents: a volumetric titration
study. J Photochem Photobiol B 1990;6:309–23.

[24] Freitas I. Lipid accumulation: the common feature to photosensitizer retaining normal and

malignant tissues. J Photochem Photobiol B 1990;7:359–61.

[25] Musser DA, Wagner JM, Weber FJ, et al. The binding of tumor localizing porphyrins to a

ﬁbrin matrix and their eﬀects following photoirradiation. Res Commun Chem Pathol
Pharmacol 1980;28:505–25.

[26] Korbelik M, Krosol G, Olive PL, et al. Distribution of Photofrin between tumor cells and

tumor associated macrophages. Br J Cancer 1991;64:508–12.

[27] Korbelik M, Krosol G, Chaplin DJ. Photofrin uptake by murine macrophages. Cancer Res

1991;51:2251–5.

[28] Kessel D. HPD: structure and determinants of localization. In: Kessel D, editor. Photo-

dynamic therapy of neoplastic diseases. Boca Raton (FL): CRC Press; 1990. p. 1–14.

[29] Jori G. Tumour photosensitizers: approaches to enhance the selectivity and eﬃciency of

photodynamic therapy. J Photochem Photobiol B 1996;36:87–93.

[30] Allison BA, Pritchard PH, Levy JG. Evidence for low-density lipoprotein receptor-

mediated uptake of benzoporhyrin derivative. Br J Cancer 1994;69:833–9.

[31] Grossweiner LI. Photodynamic therapy. J Laser Appl 1995;7:51–7.

701

M.D. Lucroy / Vet Clin Small Anim 32 (2002) 693–702

[32] Wan S, Parrish JA, Anderson RR, Madden M. Transmittance of nonionizing radiation in

human tissues. Photochem Photobiol 1981;34:679–81.

[33] Wilson BC, Jeeves WP, Lowe DM. In vivo and post mortem measurements of the attenu-

ation spectra of light in mammalian tissues. Photochem Photobiol 1985;42:153–8.

[34] Grossweiner LI. PDT light dosimetry revisited. J Photochem Photobiol B 1997;38:258–68.
[35] Star WM. Light dosimetry in vivo. Phys Med Biol 1997;42:763–87.
[36] Wilson BC, Patterson MS. The determination of light ﬂuence distributions in photo-

dynamic therapy. In: Kessel D, editor. Photodynamic therapy of neoplastic diseases. Boca
Raton (FL): CRC Press; 1990. p. 129–45.

[37] Svaasand LO. Photodynamic and photothermia response of malignant tumors. Med Phys

1985;12:455–61.

[38] Leuing M, Leuing A, Lankes P, et al. Evaluation of photodynamic therapy-induced heating

of hamster melanoma and its eﬀect on local tumor irradiation. Int J Hypertherm 1994;10:
297–306.

[39] Gibson SL, Meid KR, Murant S, et al. Eﬀects of various photoirradiation regimens on

antitumor eﬃcacy of photodynamic therapy for R3230AC mammary carcinomas. Cancer
Res 1990;50:7236–41.

[40] van Geel IP, Oppelaar H, Marijnissen JP, et al. Inﬂuence of fractionation and ﬂuence rate

in photodynamic therapy with Photofrin or mTHPC. Radiat Res 1996;145:602–9.

[41] Henderson BW, Dougherty TJ. How does photodynamic therapy work? Photochem

Photobiol 1992;55:145–57.

[42] Ochsner M. Photophysical and photobiological processes in the photodynamic therapy of

tumours. J Photochem Photobiol B 1997;39:1–8.

[43] Oleinick NL, Evans HH. The photobiology of photodynamic therapy: cellular targets and

mechanisms. Radiat Res 1998;150:S146–56.

[44] Henderson BW, Fingar VH. The role of vascular photodamage in photodynamic therapy.

Photochem Photobiol 1994;59:S1–2.

[45] de Vree WJ, Essers MC, de Bruijn HS, et al. Evidence for an important role of neutrophils

in the eﬃcacy of photodynamic therapy in vivo. Cancer Res 1996;56:2908–11.

[46] Peavy GM, Krasieva TB, Tromberg BJ, et al. Variation in the distribution of a phtha-

locyanine photosensitizer in naturally occurring tumors of animals. J Photochem Photobiol
B 1991;27:271–7.

[47] Peaston AE, Leach MW, Higgins RJ. Photodynamic therapy for nasal and aural squamous

cell carcinomas in cats. J Am Vet Med Assoc 1993;202:1261–5.

[48] Magne ML, Rodriguez CO, Autry SA, et al. Photodynamic therapy of facial squamous cell

carcinoma in cats using a new photosensitizer. Lasers Surg Med 1997;20:202–9.

[49] Theon AP, Madewell BR, Shearn VI, Moulton JE. Prognostic factors associated with

radiotherapy of squamous cell carcinoma of the nasal plane in cats. J Am Vet Med Assoc
1995;206:991–6.

[50] McCaw DL, Pope ER, Payne JT, et al. Treatment of canine oral squamous cell carcinoma

with photodynamic therapy. Br J Cancer 2000;82:1297–9.

[51] North J, Freeman S, Overbaugh J, et al. Photodynamic inactivation of retrovirus by benzo-

porphyrin derivative: a feline leukemia virus model. Transfusion 1992;32:121–8.

[52] Zeina B, Greenman J, Purcell WM, Das B. Killing of cutaneous microbial species by

photodynamic therapy. Br J Dermatol 2001;144:274–8.

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The use of surgical lasers in exotic

and avian practice

Agnes E. Rupley

*, Terri Parrott-Nenezian, DVM

All Pets Medical & Laser Surgical Center, 111 Rock Prairie Road, College Station, TX 77845, USA

Avian/Exotic/Wildlife Service, 7254 Black Road, Lake Wales, FL 33898, USA

The beneﬁts of carbon dioxide (CO

) laser use in exotics include decreased

blood loss, pain, surgery time, and healing time. Because the CO

laser seals

small vessels as it cuts, there is a decreased blood loss, which is of great
beneﬁt because many of the exotic species are quite small and therefore have
a small blood volume. The use of CO

lasers for surgery also decreases pain

because they seal nerve endings as they cut, which may also decrease self-
induced trauma after surgery. Decreased pain may also lessen postsurgical
fear and anxiety. Lasers make surgery safer and provide a quicker recovery
period. Ablation of cutaneous masses is simpliﬁed, with minimal loss of
blood. Many exotics develop a capsule surrounding an abscess. If this
capsule is not removed or is only partially removed, there is a high recurrence
rate. The CO

laser allows for the ablation of the capsule.

Laser use on exotics is a relatively new but expanding ﬁeld. Protocols are

being developed to determine which surgical techniques will beneﬁt from
CO

laser use. Techniques should be modiﬁed as needed to accomplish the

goal of the surgery. Handling techniques of each practitioner are diﬀerent
and may require a diﬀerent laser setting or tip. The following techniques
have been successfully performed in exotic animals using the AccuVet
CO

surgical laser (Lumenis, Santa Clara, CA).

Operative and postoperative thermal support is extremely important for

small exotics.

Selected techniques

Routine skin incisions and growth removals in small mammal exotics

Anesthesia: Appropriate preanesthetic followed by appropriate induction

and maintenance

Vet Clin Small Anim 32 (2002) 703–721

* Corresponding author.
E-mail address: Arupley@aol.com (A.E. Rupley).

0195-5616/02/$ - see front matter

PII: S 0 1 9 5 - 5 6 1 6 ( 0 2 ) 0 0 0 1 4 - 1

Equipment: AccuVet CO

laser with straight handpiece and 0.4-mm tip

Laser settings: Variable; 5 W continuous wave (CW) for excisional appli-

cations

Technique: The CO

laser is ideal for creating incisions in small mammal

exotics. The laser seals blood vessels as it cuts, thus decreasing the risk of
hemorrhage. It also seals nerves as it cuts, thus decreasing the potential for
postoperative pain.

Celiotomy and laparotomy procedure general comments

Anesthesia: Appropriate preanesthetic followed by appropriate induction

and maintenance. Pain relief is very important, and premedication with an
analgesic should be used in all surgery patients.

Equipment: AccuVet CO

laser with straight handpiece and 0.4- or 0.8-

mm tip

Laser settings: Variable; higher settings for cutting skin and lower set-

tings for muscle and vessel transection

Technique: The laser is ideal for making the incision in the skin for general

celiotomy procedures, such as splenectomy, exploratory laparotomy, hepatic
biopsy, cesarean delivery, gastrotomy, or enterotomy procedures. It is im-
portant to note that when opening air-ﬁlled body cavities, such as when
making an incision in the muscle wall of the coelom, there is no backstop
to absorb the laser beam or energy. Protect internal organs with a backstop
by placing an instrument or saline-soaked gauze sponge on the underside of
the tissue to be transected. The linea alba is lifted and tented and is incised
using a horizontal beam through the tented tissue so that the laser energy
is directed away from coelomic and abdominal structures. An instrument
is inserted in the coelom or abdomen, and the incision in the linea alba is
extended with the laser using the instrument as a backstop for the laser beam.

Magniﬁcation is beneﬁcial when working with small exotics. Excellent

head loupes are available and should be used when working in the abdomen
or coelom of small exotics. In addition, when working with the AccuVet
CO

laser in the coelom of exotics with air sacs, the air purge that follows

cutting with the laser can inﬂate membranes, making the surgery more dif-
ﬁcult. This air can be disconnected for short periods without harming the
laser unit. This technique can make these procedures less diﬃcult.

Orchidectomy (castration)

Rabbit

Anesthesia: Appropriate preanesthetic and induction followed by isoﬂur-

ane for maintenance

Equipment: AccuVet CO

laser with straight handpiece and 0.4-mm tip

Laser setting: 5 W superpulse (SP) or 6 W CW
Technique: The rabbit is restrained in dorsal recumbency. The scrotum

and surrounding area is prepared and draped for aseptic surgery. A 1- to

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A.E. Rupley, T. Parrott-Nenezian / Vet Clin Small Anim 32 (2002) 703–721

1.5-cm incision is made through the skin with the laser on the ventral surface
of the scrotum. The tunic is then incised with the laser exposing the testicle.
Carefully tear the tunic from the testicle. The vas deferens and vessels are
tied with an overhand knot or ligated with a small (4-0 to 5-0) absorbable
suture. The duct and vessels are transected distal to the knot or ligature and
returned to the inguinal canal. The area is inspected for hemorrhage. The
other testicle is exposed and transected in a similar manner. The skin is left
open to heal by second intention.

Rodent

Anesthesia: Appropriate preanesthetic followed by isoﬂurane or sevoﬂur-

ane induction and maintenance

Equipment: AccuVet CO

laser with straight handpiece and 0.4-mm tip

Laser settings: 5 W SP or 5 W CW
Technique: The testicles of mice, rats, gerbils, and hamsters are readily

retracted into the abdomen. They can be pushed back into the scrotum with
gentle pressure on the caudal abdomen. The procedure for orchidectomy of
rodents is similar to rabbits; however, the inguinal canals must be closed
after removing the testis. This is accomplished by closure of the tunics by
simple interrupted suture pattern with a 4-0 absorbable suture. The incision
may be closed with a drop of tissue glue.

Ferret

Anesthesia: Appropriate pre-anesthetic and induction followed by iso-

ﬂurane maintenance

Equipment: AccuVet CO

laser with straight handpiece and 0.4-mm tip

Laser settings: 6 W SP or 5 W CW
Technique: The ferret is restrained in dorsal recumbency. The ferret can

be neutered through a single prescrotal incision or two scrotal incisions. For
a prescrotal approach, the scrotum and surrounding area are prepared and
draped for aseptic surgery. A small prescrotal incision is made through the
skin with the laser. The testicles are removed with an open or closed tech-
nique. The spermatic cord, vessels, and tunics are clamped, ligated, and re-
moved. The skin is closed with a 4-0 absorbable suture in a subcuticular
pattern. If the testicles are removed through two scrotal incisions, the sper-
matic cords can be clamped and ligated or can be tied with an overhand
knot. The testicular vessels in a young ferret with small vessels can be sealed
with a defocused beam and ligated with the laser. The scrotal incisions are
left open to heal by second intention.

Prairie dog

Anesthesia: Appropriate preanesthetic and induction and maintenance

with isoﬂurane or sevoﬂurane.

Equipment: AccuVet CO

laser with straight handpiece and 0.4-mm tip

Laser settings: 6 W SP or 6 W CW

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A.E. Rupley, T. Parrott-Nenezian / Vet Clin Small Anim 32 (2002) 703–721

Technique: In young prairie dogs the testicles are located in the abdom-

inal cavity, generally through their ﬁrst year. The prairie dog is restrained in
dorsal recumbency, and the abdomen is prepared and draped for aseptic
surgery. A 1- to 1.5-cm midline incision is made with the laser anterior to
the tip of the prepuce. The linea alba is lifted and tented and is incised using
a horizontal beam through the tented tissue so that the laser energy is direc-
ted away from abdominal structures. An instrument is inserted in the abdo-
men, and the incision in the linea alba is extended with the laser using the
instrument as a backstop for the laser beam. The testicles are found in the
fat anterior to the bladder. The vessels associated with the testicles are trans-
ected with the laser, and the testicles are removed. The site is inspected for
hemorrhage. The abdomen is closed in a routine fashion with a small
absorbable suture (4-0 or 5-0), and the skin is closed with an intradermal
suture pattern. It is important to bury all sutures, because prairie dogs are
adept at removing any exposed suture. The incision can be inﬁltrated with
bupivacaine to help control self-induced trauma.

In older prairie dogs the testicles may be located in the scrotum. The

prairie dog is restrained in dorsal recumbency, and the caudal abdomen is
prepared and draped for aseptic surgery. A 1-cm incision is made through
the skin with the laser over the palpated testicle. The tunic is then incised
with the laser exposing the testicle. A closed technique is used to remove the
testicle. The tunic, vas deferens, and vessels are ligated with a small (4-0 to
5-0) absorbable suture. The duct, tunic, and vessels are transected distal to
the ligature. The area is inspected for hemorrhage. The other testicle is
exposed and transected in a similar manner. The skin is closed with 4-0
absorbable suture in a subcuticular pattern. It is important to bury all
sutures; prairie dogs are adept at removing any exposed suture. The incision
can be inﬁltrated with bupivacaine to help control self-induced trauma.

Sugar glider

Anesthesia: Appropriate preanesthetic followed by isoﬂurane or sevoﬂur-

ane induction and maintenance. Premedication with acepromazine and
pain-relief agent, such as butorphanol, may help control chewing of the inci-
sion site after surgery.

Equipment: AccuVet CO

laser with 0.4-mm tip

Laser settings: 4 watts SP or 6 watts CW
Technique: The sugar glider is restrained in dorsal recumbency, and the

caudal abdomen including scrotum is prepared and draped for aseptic sur-
gery. An incision is made in the stalk of the scrotum through the skin with
the laser. The vessels are exposed, sealed with a defocused beam, and trans-
ected distal to the sealed area. Protect surrounding tissue with a backstop by
placing a saline-soaked gauze sponge on the underside of the tissue to be
transected. The area is inspected for hemorrhage. The skin is closed with
a 4-0 absorbable suture in a subcuticular pattern. All sutures must be buried,
because sugar gliders are adept at removing any exposed suture. The inci-

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A.E. Rupley, T. Parrott-Nenezian / Vet Clin Small Anim 32 (2002) 703–721

sion is inﬁltrated with bupivacaine to help control self-induced trauma.
After the sugar glide awakes, pieces of a favored food, such as mealworms
or fruit, may distract it from chewing at the incision site.

Iguana

Anesthesia: Premedicate with acepromazine, propofol induction, intuba-

tion, and isoﬂurane or sevoﬂurane maintenance

Equipment: AccuVet CO

laser with 0.4- or 0.8-mm tips

Laser settings: 4 to 10 W SP or skin 12 CW then decrease to 8 CW for

muscle and castration

Technique: The iguana is restrained in dorsal recumbency, and the ventral

surface of the body from the sternum to pubis is prepared and draped for asep-
tic surgery. The incision is made approximately halfway between the sternum
and pubis and extends approximately half of this length. A midline or parame-
dian approach is made by tenting the skin with forceps and is incised with the
tip of a scalpel blade or scissors (or laser if a paramedian approach is used).
The large ventral abdominal vein is suspended along the ventral midline by
a short mesovasorum. Careful dissection is necessary to avoid damage to this
vessel if a midline approach is used. If damaged, this vessel should be ligated.

When a paramedian approach is used, the muscle of the body wall must

be incised after the skin incision. The muscle is thin, and hemorrhage is
minimal. The muscle is lifted and tented and is incised using a horizontal
beam through the tented tissue so that the laser energy is directed away from
coelomic structures. An instrument is inserted in the coelom, and the inci-
sion in the muscle is extended with the laser using the instrument as a back-
stop for the laser beam.

The incision is carefully extended with scissors or laser (0.4-mm tip for

smaller iguanas and 0.8-mm tip for adult iguanas), with an instrument used
as a backstop to prevent damaging the internal organs.

The right testicle is closely associated the caudal vena cava along the dor-

sal body wall. The adrenal gland is interposed between the left testicle and
the caudal vena cava along the dorsal body wall. The testicles are visualized
by retracting the viscera to the side.

The testicular capsule is gently manipulated to prevent rupture. The right

testicle is gently elevated at one pole, and a hemostatic clip is applied between
the testicle and the caudal vena cava. The laser is used to transect the tissue
distal to the clip. After the testicle is further elevated, another hemostatic clip
is applied to further ligate the vascular mesorchium. Again, the tissue is tran-
sected. This process is repeated until the right testicle is removed. If the caudal
vena cava is damaged, the defect can be closed with hemostatic clips longitu-
dinally along the caudal vena cava parallel to the wall of the caudal vena cava,
or with small suture on an atraumatic needle. The left testicle is removed after
applying hemostatic clips between the testicle and the adrenal gland.

Absorbable gelatin sponge (Gelfoam, Upjohn Co., Kalamazoo, MI) or

oxidized regenerated cellulose (Surgicel, Johnson & Johnson, Arlington,

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TX) can be used to help control hemorrhaging, but it will not seal damage to
the caudal vena cava.

The celiotomy incision is closed in two layers. The body wall is closed

using a simple continuous pattern with a small absorbable suture (3-0 to
5-0). The muscle is thin and friable and must be handled gently. The skin
is closed in an everting pattern (eg, horizontal mattress) or with skin staples.
Water should be oﬀered in a small drinking bowl to prevent soaking and
contamination of the coelom from the incision. The sutures or staples are
left in place for 6 weeks or until the next shed.

Ovariohysterectomy (spay)

Rabbit

Anesthesia: Appropriate preanesthetic and induction followed by isoﬂur-

ane for maintenance

Equipment: AccuVet CO

laser with straight handpiece and 0.4-mm tip

Laser settings: 6 W SP or 7 W CW
Technique: The bladder is expressed by gentle palpation. The rabbit is

restrained in dorsal recumbency, and the abdomen is prepared and draped
for aseptic surgery. A 2- to 3-cm midline incision is made with the laser half
way between the umbilicus and the pubis. The linea alba is lifted and tented
and is incised using a horizontal beam through the tented tissue so that the
laser energy is directed away from abdominal structures. An instrument is
inserted in the abdomen, and the incision in the linea alba is extended with
the laser using the instrument as a backstop for the laser beam. The uterus
can usually be visualized dorsal to the cranial pole of the bladder. The uterus
is then lifted through the incision with forceps. The blood vessels of the
ovaries are ligated with hemostatic clips or transﬁxing sutures of small
absorbable suture. After a saline-soaked gauze sponge is placed behind the
broad ligament, the ligament is incised with the laser to the level of the cer-
vices. The uterus of rabbits is bicornuate. There is no uterine body. Each
uterine cornua possess a cervix. The uterus is ligated at the anterior vagina
with transﬁxing ligatures of small absorbable suture (3-0 or 4-0). The uterine
blood vessels are several millimeters lateral to the uterus and should be
ligated transﬁxed to the anterior vagina. The cervices are transected taking
care to avoid contaminating the abdomen with vaginal contents. The abdo-
men is closed in a routine fashion, and the skin is closed with staples or
intradermal suture pattern. All sutures must be buried, because rabbits are
adept at removing any exposed suture. The incision can be inﬁltrated with
bupivacaine to help control self-induced trauma.

Rodent

Anesthesia: Appropriate preanesthetic followed by isoﬂurane or sevoﬂur-

ane induction and maintenance

Equipment: AccuVet CO

laser with straight handpiece and 0.4-mm tip

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Laser settings: 5 W SP or 7 W CW
Technique: The procedure for ovariohysterectomy of mice, rats, gerbils,

and hamsters is similar to rabbits; however a relatively longer incision is
required to permit observation and ligation of the ovarian vessels. The ovar-
ies are more tightly adhered and cannot be lifted through the abdominal
incision. The uterus is ligated at the cervix and transected distal to the liga-
ture. A small absorbable suture is used to close the abdomen and the skin in
a routine fashion, using an intradermal suture pattern on the skin.

Ferret

Anesthesia: Appropriate preanesthetic and induction followed by isoﬂur-

ane maintenance

Equipment: AccuVet CO

laser with straight handpiece and 0.4-mm tip

Laser settings: 6 W SP or 6 W CW
Technique: The bladder is expressed by gentle palpation. The ferret is

restrained in dorsal recumbency, and the abdomen is prepared and draped
for aseptic surgery. A 2- to 3-cm midline incision is made with the laser start-
ing 1 to 2 cm caudal to the umbilicus. The linea alba is lifted and tented and
is incised using a horizontal beam through the tented tissue so that the laser
energy is directed away from abdominal structures. An instrument is
inserted in the abdomen, and the incision in the linea alba is extended with
the laser using the instrument as a backstop for the laser beam. The uterus is
bicornuate and has a uterine body, as in cats. The uterus can often be found
just under the incision when the fat is retracted. If the uterus cannot be
visualized after manipulation of the fat, it can be caught with a spay hook
similar to the procedure in a cat. The ovarian vessels can be ligated with a 3-
0 or 4-0 transﬁxing absorbable suture or with hemostatic clips. The broad
ligament is transected with the laser, using a saline-soaked sponge as a back-
stop. The uterus is exteriorized, clamped, ligated, and excised at the cervix.
The abdomen is closed in a routine fashion, and the skin is closed with an
intradermal suture pattern.

Cockatiel

Anesthesia: Appropriate preanesthetic followed by isoﬂurane induction

and maintenance

Equipment: AccuVet CO

laser with 0.3-mm tip and hemostatic clips

Laser settings: 5 W CW
Technique: The bird is restrained in right lateral recumbency, and its left

leg is retracted caudally and rotated externally to expose the left body wall.
The left body wall is prepared and draped for aseptic surgery. A left lateral
approach with or without a ﬂap is performed. The skin is incised from the
proximal end of the pubic bone to the sixth rib dorsal to the uncinate pro-
cess. The incision is made as far dorsally as possible. Retract the left leg
further. Identify the branch of the femoral artery on the surface of the body
wall that extends perpendicular and medial to the coxofemoral joint. This

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artery is sealed with a defocused beam before transection. Incise through
the midlateral celomic musculature parallel and dorsal to the skin incision.
Elevate the musculature from the underlying coelomic structures. The mus-
cle is incised using a horizontal beam through the tented tissue so that the
laser energy is directed away from coelomic structures. An instrument is
inserted in the coelom, and the incision in the muscle is extended with the
laser using the instrument as a backstop for the laser beam with attention
to protection of the underlying structures. The incision is continued through
the seventh and eighth rib with scissors. A defocused beam can be used to
control hemorrhage. Lung tissue can be reﬂected if needed. If greater expo-
sure is needed, the incision is extended medially anterior to the pubis and or
the rib.

Place a retractor to provide exposure. Retract the proventriculus laterally

and ventrally, and tease away the ventral suspensory ligament of the proven-
triculus to visualize the ovary and cranial oviduct. Examine the uterus
before beginning the hysterectomy. The ventral ligament is bluntly dissected
to straighten the bends and folds of the uterus. The air ﬂush may be discon-
nected before dissection in the coelom. Dissect the caudal infundibulum
from the ovary with the laser. Ligate the cranial ovario-oviductal artery and
cranial oviductal vein at the base of the infundibulum with small hemostatic
clips. The vagina is double ligated with hemostatic clips at the vaginal
sphincter. The oviduct is transected between the clips, and the dorsal liga-
ment is then carefully dissected with the laser, ligating larger vessels with
hemostatic clips and sealing smaller vessels with a defocused laser beam
before transection.

Placing sutures from the body wall to ribs with 4-0 or 5-0 suture closes

the anterior coelom. The rest of the musculature and skin are closed with
5-0 or 6-0 suture in a routine fashion.

Iguana

Anesthesia: Premedicate with acepromazine, propofol induction, intuba-

tion, and isoﬂurane or sevoﬂurane maintenance

Equipment: AccuVet CO

laser with 0.4- or 0.8-mm tips

Laser settings: 4 to 10 W SP or skin 12 W CW then decrease to 8 W CW

for muscle and ovariohysterectomy

Technique: The iguana is restrained in dorsal recumbency, and the ven-

tral surface of the body from the sternum to pubis is prepared and draped
for aseptic surgery. The incision is made approximately halfway between the
sternum and pubis and extends approximately half of this length. A midline
or paramedian approach is made by tenting the skin with forceps, and the
skin is incised with the tip of a scalpel blade or scissors (or laser if a para-
median approach is used). The large ventral abdominal vein is suspended
along the ventral midline by a short mesovasorum. Careful dissection is used
to avoid damage to this vessel if a midline approach is utilized. If damaged,
this vessel should be ligated.

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When a paramedian approach is used, the muscle of the body wall must

The incision is carefully extended with scissors or laser (0.4-mm tip for

smaller iguanas and 0.8-mm tip for adult iguanas) with an instrument used
as a backstop to prevent damage to internal organs.

The technique for removing the reproductive organs is similar in gravid

and nongravid iguanas; however, the oviduct is much larger, and the blood
supply is much greater in gravid iguanas. The right ovary is closely asso-
ciated the caudal vena cava along the dorsal body wall. The left adrenal
gland is interposed between the left ovary and the caudal vena cava along
the dorsal body wall. The ovary is identiﬁed and elevated. In nonactive
ovaries, the right ovary is grasped with atraumatic forceps by its ligamen-
tous attachment. Hemostatic clips are placed between the ovary and the cau-
dal vena cava, and the ligament is then transected on the ovarian side of the
clips. The ovary is then removed. The AccuVet laser air purge may be dis-
connected before dissection in the coelom. For removing the left ovary, the
clips are applied between the left adrenal gland and the ovary to avoid
damaging the adrenal gland.

In gravid and reproductively active iguanas, the large vessels of the ovary

are double ligated with hemostatic clips or ligatures. The vessels are trans-
ected between the clips or ligatures. The ligament is transected with the
laser, and the ovary is removed.

After the oviducts are identiﬁed, the vessels of the oviducts and shell

glands are ligated with hemostatic clips or sealed with a defocused beam and
transected. Hemostatic clips or ligatures are applied at the base of each
shell gland at the junction of the uterus and the cloaca, and the uterus is
transected.

In iguanas with postovulatory egg binding, the oviducts are enlarged and

ﬁlled with eggs. The oviducts are exteriorized, allowing visualization of the
large vessels of the oviducts and uterus. Beginning at the infundibulum, the
vessels are isolated and double ligated with hemostatic clips or ligatures and
transected between the ligatures. The uterus is ligated at the cloaca and trans-
ected. The ovaries are identiﬁed and removed after removal of the oviducts.

The celiotomy incision is closed in two layers. The body wall is closed

using a simple continuous pattern with a small absorbable suture (3-0 to
5-0). Because it is thin and friable, the muscle must be handled gently. The
skin is closed in an everting pattern (eg, horizontal mattress) or with skin
staples. Water should be oﬀered in a small drinking bowl to prevent soaking
and contamination of the coelom from the incision. The sutures or staples
are left in place for 6 weeks or until the next shed.

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Abscess

Rodent, rabbit, and sugar glider cutaneous abscess

Anesthesia: Appropriate preanesthetic followed by isoﬂurane induction

and maintenance

Equipment: AccuVet CO

laser with 0.3-mm tip; 0.8 mm may be used if the

abscess is large

Laser settings: 4 W CW, and 4 W/pulse/repeat mode (AccuVet Exposure

Program 5 to 10 ms pulse, 10 Hz, 10% ‘‘on time’’) for ablation of abscess
capsule.

Technique: Most cutaneous abscesses in rodents and sugar gliders are

encapsulated. The abscess and the capsule are excised if possible. The laser
can be used to vaporize the abscess wall. All abscesses should be cultured.
Facial abscesses may arise from an infected tooth root. These abscesses may
reoccur if the underlying diseased tooth is not removed.

Avian infraorbital sinus abscess

Anesthesia: Appropriate preanesthetic followed by isoﬂurane or sevoﬂur-

ane induction, intubation, and isoﬂurane or sevoﬂurane maintenance

Equipment: AccuVet CO

laser with 0.3-mm tip

Laser settings: 4 W SP or 4 to 6 W CW
Technique: The CO

laser is ideal for making the skin incision over infra-

orbital sinus abscesses, because this site is vascular and hemorrhage can
make visualization diﬃcult. Eﬀective treatment of an abscess of the sinus
requires eliminating the pathogen and removing the abscess material. For
further details of the approach and procedure of the diﬀerent diverticula
consult Pye [1].

Box turtle ear abscess

Anesthesia: Appropriate preanesthetic followed by sevoﬂurane or propo-

fol induction and maintenance.

Equipment: AccuVet CO

laser with 0.3-mm tip

Laser settings: 3 W SP or 4 to 6 W CW
Technique: Abscesses of the middle ear are common in chelonians. They

are often caused by multiple factors related to inadequate husbandry and
are often accompanied by pneumonia. Treatment must correct the underly-
ing causes. Supportive care should be provided before surgery in debilitated
patients.

The tympanum and surrounding skin is prepared for aseptic surgery. The

ventral half of the tympanum is excised with the laser by making a semicir-
cular incision along its ventral border and incising across the center of the
tympanum. The exudate is then removed with small ear loops or curettes.
Obtain samples for culture. The cavity and eustachian tube are gently
ﬂushed with saline to completely remove all of the debris. If the turtle is not
intubated, tracheal aspiration is prevented by placement of cotton swabs in

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the caudal oropharynx. The incision is left open, and the cavity can be
ﬂushed with sulfadiazine or dilute chlorhexidine (1 part chlorhexidine to
30 parts saline).

Treatment should begin with broad-spectrum injectable antibiotics pend-

ing culture and sensitivity results. Underlying husbandry problems should
be corrected.

Ferret adrenalectomy

Anesthesia: Appropriate preanesthetic and induction followed by isoﬂur-

ane maintenance

Equipment: AccuVet CO

laser with straight handpiece and 0.4- or 0.3-

mm tips

Laser settings: 6 W SP for skin and 5 W CW for adrenalectomy; or skin

and muscle12 W, 6 watts CW for left adrenalectomy; and 2 to 4 W CW for
right adrenalectomy (may use pulse/repeat mode—AccuVet Exposure Pro-
gram CW 7 to 20 ms pulse, 20 Hz, 40% ‘‘on time’’ for tissue around the cau-
dal vena cava)

Technique: All adrenalectomy patients undergoing surgery should receive

intravenous ﬂuid therapy during the perioperative period.

Left adrenalectomy

The ferret is restrained in dorsal recumbency, and the abdomen is pre-

pared and draped for aseptic surgery. A midline incision is made with the
laser from the xiphoid to 2 to 3 cm cranial to the pubis. The linea alba is
lifted and tented and is incised using a horizontal beam through the tented
tissue so that the laser energy is directed away from abdominal structures.
An instrument is inserted in the abdomen, and the incision in the linea alba
is extended with the laser using the instrument as a backstop for the laser
beam. A complete abdominal exploratory is performed, including inspection
of the pancreas for insulinoma nodules. The colon is retracted to the right to
expose the left kidney and adrenal gland. The left adrenal gland is medial
and cranial to the left kidney. Apply a retractor to increase exposure. Dis-
sect the gland on the medial side with cotton-tipped applicator and the laser.
Gently elevate the gland as it is dissected free from the fat and small blood
vessels. The adrenolumbar vein is identiﬁed and ligated as it runs lateral and
caudal on the ventral surface of the gland. Ligation of the adrenolumbar
vein can be performed with hemostatic clips or small suture or if it is small
it can be sealed with a defocused beam. The gland is transected from sur-
rounding tissue and can be sent for histopathology. Adrenal tissue can be
vaporized with a defocused beam; however, a portion of the gland should
be excised for sample to be sent for histopathology. Closure is routine.

Right adrenalectomy

The approach is the same as for a left adrenalectomy, except that the

duodenum is elevated, and the viscera are retracted to the left to expose the

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right kidney and liver. The right adrenal gland is located under the caudate
lobe of the liver. The hepatorenal ligament is incised with scissors or the
laser to elevate the caudal tip of the liver lobe and expose the right adrenal.
The right adrenal is closely associated with the vena cava and may extend
dorsal to the vena cava. Avoid lacerating the vena cava during extraction
of the gland.

The AccuVet CO

laser air purge may be disconnected. The peritoneum

over the gland is incised with the laser. Continue dissecting around the gland
with iris or microsurgical scissors or cotton-tipped applicators. The gland is
teased away from the attachment of the vena cava. Apply hemostatic clips
or ligatures when the gland has been dissected, revealing the vessels that
enter the gland. Glandular tissue adhered close to the vena cava is excised
with scissors or laser with a pulse pattern. Sealing vessels with a defocused
beam, absorbable gelatin sponge (Gelfoam), or oxidized regenerated cellu-
lose (Surgicel) can control minor hemorrhage. If the vena cava is lacerated,
it is temporarily occluded with nontraumatic clamps, or a suture is passed
and tension is applied while it is sutured with a 7-0 or 8-0 suture with a small
atraumatic needle. Closure is routine.

Bilateral adrenalectomy

If both adrenal glands appear abnormal on inspection or palpation,

remove the entire right adrenal gland and all of the aﬀected left adrenal.
If both glands are totally removed, dexamethasone sodium phosphate
(4 mg/kg intravenously) and temporary supplementation with prednisone
orally may be given. Ferrets rarely require supplementation with ﬂudrocor-
tisone acetate.

Ferret insulinoma removal

Anesthesia: Appropriate preanesthetic followed by isoﬂurane induction

and maintenance

Equipment: AccuVet CO

laser with 0.4-mm tip

Laser settings: 6 W CW
Technique: Fasting is limited to 2 to 3 hours. Warmed intravenous ﬂuids

with 5% dextrose are begun and maintained through surgery and recovery.
The ferret is restrained in dorsal recumbency, and the abdomen is prepared
and draped for aseptic surgery. A midline incision is made with the laser from
the xiphoid to halfway between the umbilicus and the pubis. The linea alba is
lifted and tented and is incised using a horizontal beam through the tented
tissue so that the laser energy is directed away from abdominal structures.
An instrument is inserted in the abdomen, and the incision in the linea alba
is extended with the laser using the instrument as a backstop for the laser
beam. A complete abdominal exploratory is performed, including inspection
of both adrenal glands. Often, the masses are felt as ﬁrm structures in the pan-
creas. Nodules are sometimes raised and lighter or pinker than the normal

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surrounding tissue. Inspect and gently palpate the entire pancreas. The
nodules are gently lifted with atraumatic forceps and excised with the laser.
Place a saline-soaked sponge behind the tissue while excising to protect other
structures from the laser beam. The tissue surrounding the excision site is
gently wiped with saline-soaked cotton tipped swabs. Postoperative pancrea-
titis does not appear to occur. Provide medical support and treatment [2].

Ferret anal sacculectomy

Anesthesia: Appropriate preanesthetic followed by isoﬂurane induction

and maintenance

Equipment: AccuVet CO

laser with 0.4-mm tip

Laser settings: 6 W SP or 8 W CW on the skin with 6 W CW on dissection

of the sac

Technique: A Betadine (The Kendall Company, Mansﬁeld, MA) or

chlorhexadine-soaked cotton ball and a purse string suture is placed in the
rectum to prevent escape of intestinal gas, which may be ignited by the laser.
The ducts are identiﬁed at the mucocutaneous junction of the anus at the 4
and 8 o’clock positions. One duct is cannulated with a tomcat urethral
catheter. The skin over the tip of the catheter is incised with the laser. The
subcutaneous tissue is bluntly dissected with scissors and the laser until the
facial plane around the sac is identiﬁed. Dissection of this plane is continued
with the laser. The duct is transected at the opening on the anus. The inci-
sion is closed with surgical glue or a single suture. Remove the purse string
suture and cotton ball from the rectum. Take care to not damage the anal
sphincter during surgery. Remove the anal sac intact. If rupture occurs,
lavage the site with sterile saline.

Mammary gland and cutaneous masses in small mammals

Anesthesia: Appropriate preanesthetic followed by isoﬂurane induction

and maintenance

Equipment: AccuVet CO

laser with 0.3-mm tip

Laser settings: 4 W CW for mammary tissue dissection and 4 W/pulse/

repeat mode (AccuVet Exposure Program 5 to 10 ms pulse, 10 Hz, 10%
‘‘on time’’) for deproteinizing tissue

Technique: An elliptic incision is made with the laser in the skin sur-

rounding the mass. The mass is dissected from surrounding tissue with the
laser. The laser seals most vessels as the tissue is dissected. The surrounding
tissue is ablated using a ‘‘defocused’’ beam. Subcutaneous tissues are closed
with a 4-0 or 5-0 absorbable suture. The skin is closed with a 4-0 or 5-0
absorbable suture in a intradermal suture pattern. In guinea pigs there is lit-
tle redundant tissue in the inguinal area. If a bilateral mastectomy is
required, it should be staged 2 to 4 weeks apart, or a rotation or advance-
ment ﬂap of the caudal abdomen is performed to facilitate closure of the
skin. Complete mastectomy is not possible in rats and mice because of the

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diﬀuse location of the mammary tissue, making recurrence common. All
sutures must be buried, because exposed suture is easily chewed. The inci-
sion can be inﬁltrated with bupivacaine or other local anesthetic to help con-
trol self-induced trauma.

Limb amputation

Anesthesia: Appropriate preanesthetic followed by appropriate induction

and maintenance

Equipment: AccuVet CO

laser with 0.3- or 0.4-mm tip (0.8 mm for large

species)

Laser settings: Variable
Technique: The CO

laser is ideal for limb amputations in exotics. The

laser seals blood vessels as it cuts, thus decreasing the risk of hemorrhage.
It also seals nerves as it cuts, thus decreasing the potential for postoperative
pain. The laser seals the small vessels in the muscle tissue as it cuts, thus
decreasing hemorrhage and allowing amputation of the wing in birds at the
shoulder a viable option. Nerves are inﬁltrated with bupivacaine before
transection. Consult ‘‘Suggested Readings’’ for further details of limb ampu-
tations for diﬀerent species.

Summary

There are many beneﬁts of the CO

laser in exotic animal practice. Their

use is limited only by the imagination. Techniques presented are to be used
as guidelines.

Diode lasers

The diode laser overlaps the carbon dioxide laser in many clinical uses in

small mammals. Most models are equipped with a working handpiece and
multiple diameter optical ﬁbers. The wavelength of the diode is in the
near-infrared range (810–980 nm). The absorptive capacity of water is mini-
mal at this wavelength. The diode laser will penetrate deeper into the non-
pigmented areas compared with the CO

laser [3]. Lower settings are

required when working with tissues that have higher water content. Excising
lipomas and cysts can cause increased thermal damage to surrounding tissue
if the operator lingers over a small area too long. Boiling and popping of the
tissue tends to occur before the desired ablation of the mass. The resulting
liquifactive necrosis that surrounds the target tissue is often seen days later.
Therefore, recommended use of diode lasers in small mammals for excision
or ablation of ‘‘lumps and bumps’’ should be limited to vascularized (due to
the hemoglobin pigment) areas.

Endoscopic work with the diode laser in birds has been very rewarding.

The optical ﬁbers available for energy delivery can be used through the

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biopsy or working ports of most operating ﬂexible or rigid endoscopes.
Laser application can be in either contact or non-contact modes, with non-
contact delivery used most often. Flat or cleaved ﬁbers that are 400 lm in dia-
meter are most commonly used for the described applications. In addition,
this practice uses a surgical hysteroscope (continuous irrigation outpatient
operating hysteroscope, R. Wolf, Vernon Hills, IL) that has three operat-
ing ports. One port is used for the laser ﬁber, one for the smoke evacuator,
and one for grasping or biopsy instruments. The combination of high
oxygen ﬂow rates and lack of carbonization/charring using the 980-
diode laser often provides a clear ﬁeld of vision without using the smoke
evacuator.

Diode laser procedures

Avian testicular ablation

Due to the highly vascular nature of the avian testicle, the diode laser is

an excellent tool to ablate the testis while leaving the surrounding renal
artery and vein intact [4]. Both testes should be ablated. The surgical
approach is the same as that for avian sex determination, a left lateral
approach caudal to the last sternal rib, proximal to the femur [5].

Testis varying from 1.5 to 3 mm in length can be ablated using a sweeping

motion with a 400 lm optical ﬁber at the power setting of 6 W in non-
contact mode (Figs. 1–2). Another operator may use the diode laser in a
pulsed delivery mode to decrease thermal scatter and increase precision. The
ﬁrst eﬀect seen is blanching of the tissue followed by contraction. Care must
be taken in the smaller avian patient not to cause collateral damage to the
underlying vasculature. If collateral photothermal damage does occur, the
bird will hemorrhage from tissue undergoing coagulative necrosis two to
three days postoperatively. Much of the testicle will be immediately
destroyed when contraction occurs. However, the latent thermal eﬀects con-
tinue for weeks after the surgery, and when reexamined, complete removal
of the testis can be appreciated. Pigmented testis, as in some cockatoos, will
readily absorb diode laser energy; care must be taken not to over heat the
surrounding and underlying tissues.

Avian ovary ablation

Young immature birds are the best candidates for ablation of the ovary.

Using a 400 lm ﬁber tip in non-contact mode at laser power setting of 4 to 6
W for a 1 to 3 mm diameter gonad, the ovary can be vaporized [4]. Single
follicles of 1 mm or greater in diameter must be ablated separately using
an increased laser power setting of 6 W. Risk of coagulative necrosis of renal
vessels increases as the follicle size increases. Using a pulsed energy delivery
mode increases precision and decreases potential collateral thermal eﬀects.

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Oviduct ligation

In a mature egg laying bird, it is next to impossible to remove the ovary

with the large follicles developing. Medically reducing the active follicle by
using certain drugs such as leuprolide acetate (Lupron, TAP Pharmaceuti-
cals Inc., Lake Forest, IL) can be attempted before removal; however, the
risk of surgical complications such as egg yolk peritonitis is increased. Ovi-
duct ligation using the endoscopically applied diode laser energy will stop

Fig. 1. Preoperative endoscopic view of avian testicle prior to diode laser (980 nm) ablation.

Fig. 2. Intraoperative endoscopic view of avian testicle during diode laser ablation.

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egg laying and does not require postoperative hospitalization. Using the
same surgical approach as described for ovarian ablation, the infundibulum
is ablated next to the ovary using a 400 lm ﬁber and a laser power setting of
6 to 7 W in non-contact mode. Care must be taken to avoid any large fol-
licles during laser ablation. For increased precision, pulsed energy delivery is
used when near the large vessels or follicles on the mature ovary.

Avian cloacal papillomas

This procedure works better with the diode laser than with the CO

laser

due to the accessibility gained through endoscopic visualization. After lavag-
ing the cloaca with warm lactated ringers solution and performing an ade-
quate exam, papillomas can be ablated through the scope using a 400 lm
ﬁber at a power setting of 5 W using pulsed delivery in a non-contact mode.
The tissue in this region is highly vascular and the cloacal wall is very thin.
As soon as the papilloma contracts due to thermal coagulation, laser energy
application must stop. If laser application is continued, collateral thermal
changes may cause necrosis and rupture of the cloacal wall with retention
of feces in the subcutaneous layers around the area. The bird may recover
from anesthesia and strain for the next 24 to 36 hours post operatively; how-
ever, this will subside. If rupture of the wall occurs days later, the bird will
start straining again and pass little or no feces. The vent area will enlarge
with the retained fecal material.

Avian renal mass debulking/removal

Ablation of renal masses in budgerigars and cockatiels has been accom-

plished using a 400 lm ﬁber with a laser power setting of 8 W and contin-
uous wave delivery in a non-contact mode. The laser is moved over the mass
in a gentle, sweeping motion until contraction and a brown discoloration
occurs. Remaining tissue can be ablated using a pulsed delivery setting
(20% ‘‘on time’’).

Reptile surgery

The same laser parameters and power settings used in the avian patients

are used for the reptile patients as well. An insuﬄator, not needed in avian
patients due to the air sac system, should be used in reptiles to provide ade-
quate visibility and increased space between the organs.

Ferret adrenalectomy

For masses 2 to 9 mm in diameter, endoscopic ablation with the diode

laser is very successful. An insuﬄation device is needed. A left adrenal tumor
is easily accessible through a left of mid-line approach. Dissection of fatty
tissue around the adrenal can be accomplished with special laparoscopic
scissors through the port. Once the adrenal is located, using the diode laser

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A.E. Rupley, T. Parrott-Nenezian / Vet Clin Small Anim 32 (2002) 703–721

at 8 to 10 W of power in a continuous wave mode, a 400 lm ﬁber is used for
photothermal ablation/coagulation in non-contact mode.

The right adrenal is accessed to the right of the mid-line and is much

more diﬃcult to visualize due to it’s position under or immediately adjacent
to the vena cava. Laser power is reduced to 4 to 6 W CW during ablation/
coagulation of adrenal tissue adjacent to the vena cava. A pulsed mode may
also be used for ablating any remaining pathologic tissue. The major disad-
vantage of this approach is that there is no method of controlling massive
hemorrhage if the vena cava is inadvertently incised.

Summary

Use of diode laser energy with ﬁberoptic endoscopic delivery in exotic

animal and avian practice oﬀers a minimally invasive method for perform-
ing speciﬁc surgical procedures. Trauma and blood loss are minimized, but
the absorption characteristics of the diode laser wavelengths (805/980 nm)
must be considered to avoid potential postoperative complications due to
collateral photothermal coagulative necrosis.

Acknowledgment

Thank you to Dan Jordan, DVM, for additional input of AccuVet

laser settings.