Differences in Wound Healing 
between Horses and Ponies

Jacintha M. Wilmink, 

DVM

, 

PhD

,

 Diplomate

 

RNVA

Horses and Ponies: Same Species, Different 
    Healing Characteristics
Clinically Apparent Phases during Wound 
    Healing
  Infl ammatory Phase
  Formation of Granulation Tissue
  Wound Contraction
  Epithelialization
First Intention Healing (Primary Wound 
    Closure)

Second Intention Healing
  Infl ammatory Phase
  Formation of Granulation Tissue
  Wound Contraction
  Epithelialization
Clinical Implications
  First Intention Healing
  Second Intention Healing
Conclusion
References

Horses and Ponies: Same Species, Different Healing Characteristics

Over the course of millions of years the horse evolved from a small forest dweller to a large ungulate which 

inhabited the vast open plains of the temperate zone. It became a so-called “fright and fl ight” animal whose 
instinctive reaction to danger is to run.

1

 Evolution took place as a response to various environmental and climatic 

challenges while selection by mankind resulted in the development of special features. Both evolution and 
selection led to the large variety of breeds known today.

The equine species can be roughly subdivided into horses and ponies; this is offi cially a matter of the height 

at the withers of an adult (ponies are 

<1.48 meters). Whether ponies are just small horses has been disputed for 

decades. The discussion of this topic, with respect to wound healing, started in the 1980s, when Bertone, et al. 
(1985)

2

 found in a study on second-intention healing that ponies healed faster without the formation of exuber-

ant granulation tissue (EGT), in contrast to horses. However, other authors reported the development of EGT 
in ponies,

3,4

 and the faster healing of wounds in ponies could not be confi rmed.

4

 Because a difference in wound 

healing between horses and ponies might provide information about the basic biology of equine wound healing 
and about the complications commonly associated with repair in this species, Wilmink, et al. performed a series 
of experiments to investigate wound healing in both horses and ponies. They proved that ponies heal faster 
and with fewer complications than do horses

5–7

  and demonstrated that these differences were based on the 

effi ciency and capacity of the leukocyte to produce several mediators.

8,9

 The details of these studies will be dis-

cussed herein.

What remains to be elucidated is the cause of the observed differences in healing between horses and ponies. 

It may well be that the longer period of domestication of the horse has precluded natural selection against poor 
healing, since the wounded horse was/is tended to by man. Additionally, the artifi cial selection of features such 
as height, athletic capacity, and appearance might have favored the development of some diseases and undesir-
able characteristics, possibly including the reduced effi ciency of leukocytes. Moreover, horses with poorly healed 
wounds, which limit their athletic ability, are often used for breeding, which may perpetuate the cycle. In 

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