## Overview Melanomas in the perineal, inguinal, and ventral tail-base regions are extremely common in gray horses. They appear as firm, dark nodules. Many remain benign for years, but they can enlarge, obstruct defecation or urination, or metastasize internally. ## Causes Genetic predisposition linked to the gray coat color mutation. ## Diagnosis Visual examination. Biopsy if the diagnosis is uncertain. Staging ultrasound or radiographs for internal spread when masses are large. ## Treatment Monitoring for small lesions. Surgical excision, laser, cisplatin, or other local therapies for problematic masses. Systemic treatments are under investigation. ## Recovery and Prognosis Good for local control of accessible lesions. The overall melanoma burden in gray horses is progressive. ## Prevention None. Regular monitoring of gray horses.
firm dark nodules in the perineal or inguinal region; may obstruct defecation or urination if large; possible internal metastasis
## Overview Melanomas in the perineal, inguinal, and ventral tail-base regions are extremely common in gray horses. They appear as firm, dark nodules. Many remain benign for years, but they can enlarge, obstruct defecation or urination, or metastasize internally. ## Causes Genetic predisposition linked to the gray coat color mutation. ## Diagnosis Visual examination. Biopsy if the diagnosis is uncertain. Staging ultrasound or radiographs for internal spread when masses are large. ## Treatment Monitoring for small lesions. Surgical excision, laser, cisplatin, or other local therapies for problematic masses. Systemic treatments are under investigation. ## Recovery and Prognosis Good for local control of accessible lesions. The overall melanoma burden in gray horses is progressive. ## Prevention None. Regular monitoring of gray horses.
firm dark nodules in the perineal or inguinal region; may obstruct defecation or urination if large; possible internal metastasis