Grey horses are at high risk for Melanoma. Statistics shows that 80% of grey horses over the age of 15 will have Melanoma. Melanoma commonly develops on Grey horses around the lips and eyes and under the tail. The cases of Melanoma in Grey horses spreads into three categories. 1: The horse develops Melanoma very slowly over the course of many years without signs of cancer. 2: The horse develops Melanoma which turns from benign (non cancerous) into malignant (cancerous). 3: The horse develops Melanoma which is malignant from the beginning. Although Grey horses have a high tendency of getting Melanoma is is likely that there is a secondary gene working with the Grey gene causing the high rate of Grey horse Melanoma cases.