The Incidence of Skin Cancer In Horses

The January 1 issue of the Journal of the American Veterinary Medical Association has a report on a study on cutaneous cancers in horses from the central area of the United States and Canada. Researchers and clinicians from Colorado State University and the Western College of Veterinary Medicine at the University of Saskatchewan collaborated on this research study.

The most common skin tumors reported were sarcoids, squamous cell carcinomas and melanomas. The exposure to UV (ultraviolet) radiation influenced some cancer frequencies. Samples from Colorado had a higher number of tumors associated with that exposure?squamous cell carcinomas, hemangiomas and hemangiosarcomas being among the increased tumors. This suggests that horses with heavy UV exposure need to be pastured at night and have sun lotions applied when working during the prime daylight hours for UV exposure?10 a.m. until 4 p.m.

Appaloosa and American Paint Horses were at higher risk for any tumors associated with UV exposure, undoubtedly due to the areas of white hair and pink skin found with these breeds. Arabians had a higher risk of melanoma. This cancer is often associated with the gray color, so that could be a correlation for this breed, since gray is a common Arabian color. Thoroughbreds seemed to have an increased risk of cutaneous lymphoma while pony and draft breeds tended to have benign soft-tissue growths. Morgans and ponies had more basal cell tumors than other equines.? Soft-tissue sarcomas showed up at higher risk in donkeys and mules.

While there may not be many actions you can take? other than limit UV exposure?to minimize your horse’s risk from skin cancers, prognosis is always better with early detection.

More cancers were detected during the summer months. This could be due to a number of factors. Owners tend to spend more time with their horses in good weather. Horses are shed out and growths are more easily seen.

It would be a good idea to set aside one day a month to plan on going over your horse carefully to look for any new growths or changes in long-term growths. So, pick a date like the 15th of every month and do a quick body check of your horse.

Zinc oxide or most human high SPF sun-shield lotions can be used on your horse, especially areas like the nose, which is usually easily burned.

Deb M. Eldredge, DVM, Contributing Veterinary Editor

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