The grim diagnosis of 2005 champion sprinter Lost in the Fog’s inoperable tumors has raised questions about the occurrence of cancer in equines.

“It’s not a common problem in horses in general,” said Elizabeth Davis, DVM, Dipl. ACVIM, an assistant professor and the head of equine medicine and surgery at Kansas State University. “Horses don’t live as long as some other species do, and usually, cancer is a disease of geriatric individuals. Their lifestyle is a little more controlled so that makes it a little less likely.”

Forms of cancer found in horses include melanoma, lymphoma, squamous cell carcinoma, granulosa cell tumor, and cancers of the pituitary gland, thyroid gland, gastrointestinal tract, and bone.

Though statistics show more than 80% of gray horses over the age of 15 will develop at least one melanoma in their life, the tumors are usually benign. The most common form of metastasizing tumor is lymphoma. This tumor spreads to various parts of the body, and there are very limited treatment options for this form of cancer, which affects less than 1% of the horse population