Melanomas in Horses

Melanomas are common equine skin tumors, particularly in older gray horses. Some estimates put the incidence of melanomas as high as 80% in gray horses over the age of 15.

The tumors can occur below or above the skin surface, and are often found around the anus and on the underside of the horse’s tail. Unlike human melanomas, these tumors in horses are generally slow-growing and may be present for many years without causing significant problems.

Surgical removal of melanomas is sometimes successful with small tumors, but many melanomas tend to recur. Unless they interfere with the use of tack, they are not usually removed.

Large melanomas may crack open or become irritated, and the raw tissue and bleeding attract flies. Owners should attempt to clean blood from around the tumors and use fly spray during warm weather to keep horses comfortable.