Melanoma affects the vast majority of gray horses as they age, and early recognition and management prevents significant suffering from this common condition.
Equine melanoma creates significant welfare concerns as tumors progress, particularly when located in areas that interfere with normal function. Perianal melanomas that compress the rectum interfere with defecation, causing pain and discomfort that affects quality of life significantly. Ulcerated tumors become infected and create chronic pain and wound management challenges. The high prevalence of melanoma in gray horses means owners of gray horses should monitor regularly for new or changing masses, particularly in the typical locations. Early intervention when tumors are small offers the best chance of successful management. The welfare decision about when tumor progression has compromised quality of life sufficiently to warrant euthanasia requires careful assessment of the horse's ability to defecate, eat, move, and engage in normal behaviors.