What neoplastic disease can cause epistaxis in horses?

• A. Amyloidosis
• B. Osteosarcoma
• C. Lymphoma
• D. Melanoma

Answer: (A)

Epistaxis in horses often comes from a mass within the nasal cavity or nearby sinuses that erodes blood vessels as it grows. Among the tumors listed, melanoma is the one most classically associated with nasal bleeding, especially in gray horses, because these tumors frequently arise in nasal mucosa and can ulcerate and bleed as they expand. Osteosarcoma and lymphoma can involve nasal structures and cause bleeding too, but they’re less commonly encountered in the nasal area compared with melanoma. Amyloidosis, on the other hand, is a deposition disease rather than a neoplasm and isn’t typically described as a nasal tumor causing epistaxis. So, the neoplastic disease most likely to cause epistaxis in a horse is melanoma.