Melanoma is extremely common in grey horses and requires careful monitoring. While often slow-growing, melanomas can become malignant and cause serious welfare problems.
Grey horse melanomas cause welfare concerns when they grow large enough to interfere with defecation, urination or tack fit. Internal metastases cause serious disease and suffering. Regular monitoring allows early intervention before tumors obstruct function. Owners should photograph lesions to track growth rates and seek veterinary review of rapidly growing tumors.