Skin Problems in Horses: Genetic Conditions

Sunburn, Culicoides hypersensitivity, pemphigus foliaceus, melanoma, sarcoids. These and other skin diseases negatively impact equine health. Although some skin conditions in horses develop primarily from environmental causes, such as sunburn, others have a genetic component, like melanomas. According to experts, knowing which skin conditions result from genetic anomalies will help facilitate diagnosis, treatment, and even prevention.

As described in a recent study*, when a skin condition is largely a result of genetic rather than environmental factors, it is referred to as “genodermatosis.” In horses, five genodermatoses with a known genetic cause have been identified.

1. Hereditary equine regional dermal asthenia (HERDA) in Quarter Horses. Affected horses have hyperextensible skin and are easily scarred. The disease is usually noted when young horses are being saddle broke, as skin on the back seems especially affected.

2. Junctional epidermolysis bullosa (JEB) in American Saddlebreds. This condition causes the skin to blister and erode following even very light contact or friction.

3. Junctional epidermolysis bullosa (JEB) in Belgian drafts and other draft breeds. The clinical picture of this condition is very similar to the one in American Saddlebreds but involves a different gene and mutation.

4. Hoof wall separation syndrome in Connemara ponies. Affected ponies suffer separation of the dorsal hoof wall at the front of the foot from the underlying structures. This painful condition can lead to laminitis.

5. Incontinentia pigmenti in Quarter Horses and Warmbloods. A condition similar to that seen in humans, resulting in areas of hair loss and lack of skin pigmentation.

Each of these anomalies is due to a single error in the genetic code of a single gene and are passed on to offspring through classic Mendelian genetics.

“One of the key points of the article is that knowing whether a horse has or carries the mutation for one of these conditions not only helps owners plan appropriate matings but also helps veterinarians better understand how the skin functions. This knowledge will allow veterinarians and owners keep this vital, complex organ healthy in all horses, not just those affected with a genetic condition,” explained Kathleen Crandell, Ph.D., an equine nutritionist for Kentucky Equine Research (KER), located in Versailles, Kentucky.

While research in this field progresses, help maximize your horse’s skin health by using traditional approaches.

   - Ensure your horse’s diet is complete, meeting, and not exceeding, all of the recommended values for the six essential nutrients: carbohydrates, protein, fat, vitamins, minerals, and         water;
   - Prevent insect bites and sunburn as much as possible;
   - Avoid rain rot by keeping horses thoroughly groomed and by regularly checking under sheets and blankets;
   - Routinely treat horses for both internal and external parasites, including pinworms and mange, if necessary;

Source: Equinews