280 © 2006 The Authors. Journal compilation © 2006 European Society of Veterinary Dermatology. 17; 280-283

Blackwell Publishing Ltd Demodicosis in nine prairie dogs (Cynomys

ludovicianus)

Vladimir Jekl*, Karel Hauptman*, Edita

Jeklova† and Zdenek Knotek*

*Avian and Exotic Animal Clinic, Faculty of Veterinary Medicine,

University of Veterinary and Pharmaceutical Sciences, Brno,

Czech Republic

†Veterinary Research Institute, Brno, Czech Republic

Correspondence: Vladimir Jekl, MVDr, PhD, Avian and Exotic Animal

Clinic, Faculty of Veterinary Medicine, University of Veterinary and

Pharmaceutical Sciences, Brno, 1-3 Palackeho St., 612 42 Brno,

Czech Republic. Tel.: [phone];

E-mail: [e-mail]

Abstract

This case report describes the clinical signs and treatment of demodicosis in nine pet prairie dogs

(Cynomys ludovicianus). Clinical records including history, clinical examination, microscopic evaluation

and fungal culture of the skin lesions were available for

all nine animals. In seven animals, blood was obtained

for haematological and biochemical analyses. Clinical

signs comprised bilaterally symmetrical alopecia extending

from the middle part of the back down to the skin

of the thighs and the dorsal and ventral parts of the

tail. Demodex mites were found in skin scrapings from

all cases. Treatment with amitraz at 250 p.p.m.

resulted in resolution of lesions and hair regrowth.

This is the first report of demodicosis in this species.

Accepted 16 May 2006

Case report

Nine prairie dogs (6 males, 9-24 months old and 3 females,

6-12 months old) were presented by different owners in

the Czech Republic. Animals were kept separately and

could move freely around the house. They were fed on

hay, rabbit pellets, mixed rodent cereal and fruits (mostly

apples). The prairie dogs had never been in contact with

any other animals since they were bought from a pet shop

by their current owners. No treatment had been given for

the skin condition prior to presentation.

All owners reported progressive hair loss over the dorsum,

lasting for periods of 1-3 months. General health was

not affected and pruritus was only reported in one male.

Conscious physical examination included activity level

and behaviour, nutritional status, chest auscultation and

rectal temperature. Further examination under general

anaesthesia (isoflurane/oxygen, isoflurane, Rhodia, Torrexpharma,

GmbH, Vienna, Austria) included abdominal

palpation, inspection of oral cavity, evaluation of the skin

lesions and blood sampling.

Bilateral symmetrical alopecia was seen in all nine

animals. The alopecia extended from the middle part of

the dorsum down to the skin of the thighs and the dorsal

and ventral parts of the tail (Fig. 1). In eight patients, the

alopecia was nonpruritic and without visible signs of

erythema or scaling. When lesions had been present for

longer than 6 weeks, the alopecic areas became mildly

hyperpigmented. One animal showed a pruritic, pustular

dermatitis on the outside of the thighs.

Seven deep scrapings were taken using a scalpel blade

from each animal. One sample was taken from the dorsal

side of the tail base, one from the each lateral thigh, one

from each flank, and two from the margin of the lesions.

Part of the samples was examined microscopically in

paraffin oil and potassium hydroxide. The other part was

cultured for dermatophytes (DTM, Delasco, IA, USA).

Microscopic examination of all the skin scrapings revealed

an occurrence of one to 10 adult demodex mites (Fig. 2)

as well as the presence of few mite eggs (0-3). Larval

developmental stages were not found. The mites were all

of the short form morphology and ranged from 190 to

250 m in size. Slim oval eggs ranged in size from 55 to

70 m. Fungal culture results were negative in all cases.

Blood samples for haematological and biochemical

analyses were taken from the cranial vena cava in seven

patients.1 Blood smears were stained with May-Grünwald/

What is known about the topic of your paper

• Demodicosis has been diagnosed in other species.

What your paper adds to the field of veterinary

dermatology

• This is the first documented case of demodicosis in

prairie dogs.

Figure 1. Photo: Alopecic skin changes in prairie dog.

© 2006 The Authors. Journal compilation © 2006 European Society of Veterinary Dermatology. 281

Demodicosis in prairie dogs

Giemsa-Romanowski stains and evaluated. Serum biochemical

analyses included the following parameters: total

protein, albumin, globulins, urea, creatinine, glucose, aspartate

aminotransferase, alanine aminotransferase, alkaline

phosphatase, creatine kinase, sodium, potassium, calcium

and phosphorus. The biochemical analyses were conducted

using the CobasMira (Roche, Basel, Switzerland) and

Atomspec (Hilger 1550, Cambridge, UK) analysers. Haematological

and biochemical analyses were within reference

ranges for all animals.2

Treatment was performed with amitraz dips (Ectodex,

Intervet International B.V., Boxmeer, the Netherlands) at a

concentration of 250 p.p.m. for 3-5 min at 4-day intervals

for a period of 2 months. The amitraz solution was simple

sponged onto the animal. A typical treatment outcome is

shown in Figs 3 and 4. In all cases, the fur reappeared

within a period of 5-10 weeks after the beginning of

therapy. Folliculitis and pustular dermatitis in one patient

disappeared within 6 days after the beginning of treatment

without additional antibacterial therapy. Follow-up scrapings

from the same regions (seven sites) 1 and 2 months after

completion of therapy were negative.

Discussion

Demodicosis is a skin disease caused by ectoparasitic

mites from the genus Demodex (family Demodecidae),

and is typically manifested by alopecia, inflammation of

hair follicles and sebaceous glands. If the disease only has

a focal distribution on the body, it is usually nonpruritic.

A generalized follicular form with pruritus is reported in dogs,

cats and rabbits.3 Demodicosis is also described in many

species of small mammals such as rabbits,3 guinea pigs,4

hamsters,5,6 hedgehogs,7 gerbils,8 rats9-11 and ferrets.12 In

several other animals, the mites have not been precisely

determined.12-14 In most animals, these mites live commensally

in the skin and only when the immune system is

compromised does the mite population increase and the

disease develop.3 Two types of demodex mites are described:

follicular mites resembling Demodex canis and epidermal

forms with close taxonomic resemblance to Demodex criteti.3

The epidermal forms have a shorter morphology and have

been reported to cause a pruritic dermatosis in cats.15

Funk2 listed fleas, ticks and lice as ectoparasites

causing skin diseases in prairie dogs. He also reported

parasitic infestation of undetermined sarcoptiform parasites

that caused alopecia. To the author's knowledge, this is

the first report of demodicosis in this species. All nine prairie

dogs developed spontaneous demodicosis due to a

mite with a short body. This mite resembles Demodex

Figure 2. Photomicrograph: Demodex mite. Bar = 100 m.

Figure 3. Photo: Same case as Fig.1. Response to amitraz treatment

- day 15.

Figure 4. Photo: Same case as Fig. 1. Response to amitraz treatment

- day 40.

282 © 2006 The Authors. Journal compilation © 2006 European Society of Veterinary Dermatology.

Jekl et al.

gatoi in cats and Demodex criceti in hamsters,15 but it

was not precisely speciated. In one patient with pruritic

pustular dermatitis we found the highest numbers of mites

(10 adults, 3 eggs), but it is not possible with one case to

link the number of mites to disease severity. When dealing

with bilaterally symmetrical alopecia in small mammals,

other ectoparasites, barbering syndromes, dermatomycosis,

hormonal dermatoses, and congenital and hereditary

alopecias should be considered.3 In these cases, there

was no history of congenital problems, the owners had

not noticed any excessive grooming or barbering and

fungal infections were ruled out by culture. There was no

evidence on clinical, haematological or biochemical analysis

of hormonal problems, although specific endocrine assays

have not been validated in this species and were not

carried out. Although in all described cases the first symptoms

of skin disease appeared from October to March, no

relationship with oestrus or hormonal disturbance would

be expected in animals of this age.2 The demodicosis

appears to have been a primary development because no

corticosteroids had been administered to any of the prairie

dogs, and there was no evidence of disease likely to cause

immunosuppression. Whether or not there was some

source of stress is not known. As we did not see this

disease in adult animals (prairie dogs under 24 months

of age are known as subadults), the condition may be

analogous to juvenile onset demodicosis in dogs.

The clinical diagnosis was supported by the positive

response to treatment with amitraz, but further reports

are necessary before we can conclude that the disease

does not resolve spontaneously in some cases. No adverse

effect of the amitraz dips was observed. In dogs with

demodicosis, baths in bactericidal shampoos and complete

hair removal are recommended as adjunctive treatments.3

However, this would not to be recommended in small

mammals because of the risk of hypothermia. Possible

alternative treatments such as ivermectin as reported in

hamsters16 and koalas,17 or selamectin as reported in

hedgehogs18 may also prove to be effective in prairie dogs.

The source of mites in these cases was not determined,

because the owners did not have any other animals. The

mites could have been present since birth, or they could

have been acquired from other animals in pet shops,

where many hamsters, rabbits, rats and cats were present.

The precise host specificity of demodex mites in prairie

dogs is not known. We have examined scrapings from 20

clinical healthy prairie dogs and did not find mites, but this

would be typical of the situation in dogs and cats. Further

investigations will be needed to determine if the mites are

genuinely present at low numbers in all animals.

Acknowledgements

The authors would like to thank Prof. G.M. Dorrestein,

DVM, PhD, (NOIBVD, the Netherlands) and MVDr David

Modry, PhD, (Department of Parasitology, University of Veterinary

and Pharmaceutical Sciences, Brno, Czech Republic)

for their valuable comments, critical reading of the

manuscript and their helpful suggestions and to the technical

staff of the Avian and Exotic Animal Clinic, University

of Veterinary and Pharmaceutical Sciences, Brno, for their

skilful assistance.

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Résumé Ce cas clinique rapporte les signes cliniques et le traitement de la démodécie chez neuf chiens

de prairie (Cynomys ludovicianus). Les données anamnestiques, cliniques, microscopiques et le résultat de

cultures fongiques ont été étudiés. Pour sept animaux, des analyses biochimiques et hématologiques ont

également été réalisées. Les signes cliniques regroupaient une alopécie bilatérale et symétrique, s'étendant

du milieu du dos aux cuisses et sur les parties ventrale et dorsale de la queue. Des Demodex ont été

© 2006 The Authors. Journal compilation © 2006 European Society of Veterinary Dermatology. 283

Demodicosis in prairie dogs

retrouvés sur les raclages dans tous les cas. Un traitement à base d'amitraze à 250 ppm a permis une

disparition des lésions et la repousse du poil. Il s'agit du premier rapport de démodécie dans cette espèce.

Resumen El caso documentado en este artículo describe los signos clínicos y el tratamiento frente a

demodicosis en nueve perrillos de las praderas (Cynomys ludovicianus). Los documentos clínicos incluida

la historia, el examen clínico, la evaluación microscópica y el cultivo de hongos de las lesiones de la piel

fueron completados en los nueve animales. En siete de los animales también se obtuvo sangre para el

análisis hematológico y bioquímico. Los signos clínicos incluyeron alopecia simétrica bilateral extendiéndose

desde la linea media del tronco ventralmente hacia la piel de los muslos y las zonas dorsales y ventrales de la

cola. Se encontraron ácaros del género Demodex en raspados de la piel en todos los animales. El tratamiento

con amitraz a 250 ppm resultó en la resolución de las lesiones y en crecimiento del pelo. Este artículo es

el primer reporte de demodicosis en esta especie.

Zusammenfassung Dieser Fallbericht beschreibt die klinischen Symptome und die Behandlung von

Demodikose bei neun als Haustiere gehaltenen Präriehunden (Cynomys ludovicianus). Klinische Daten bzgl.

Anamnese, klinischer Untersuchung, mikroskopischer Evaluierung und Pilzkultur der Hautveränderungen

waren von allen neun Tieren vorhanden. Bei sieben Tieren wurde eine Blutprobe entnommen für eine

hämotologische und biochemische Analyse. Die klinischen Symptome bestanden aus bilateralem symmetrischen

Haarausfall, welcher sich von der Mitte des Rückens bis zu den Oberschenkeln erstreckte, sowie

auf die dorsalen und ventralen Teile des Schwanzes. Demodexmilben wurden in Hautgeschabseln von allen

Fällen gefunden. Die Behandlung mit Amitraz bei einer Dosierung von 250 ppm resultierte in Rückbildung

der Veränderungen und Nachwachsen der Haare. Es handelt sich hier um den ersten Report von

Demodikose bei dieser Spezies.

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