Uveal Melanoma in an Aradi Goat (Capra aegagrus hircus)

A 6-year-old Aradi goat (Capra aegagrus hircus) was admitted with glaucoma of the left eye. Blood clots and a yellow exudate covered the cornea and sclera. Ocular examination found glaucoma, exophthalmos and a distorted iris. Because of the blindness and pain, surgical enucleation of the left eye was performed. Gross examination through the mid-sagittal section of the enucleated globe revealed a pigmented mass occupying the anterior chamber. It had invaded the peripheral cornea and extended to the dorsal iris. Histologically, the mass was composed of pleomorphic, epithelioid neoplastic cells with high-grade cellular atypia. Scattered cells contained brown-black pigment. Bleached sections demonstrated 6-7 mitoses per 10 high-power fields and the cornea displayed squamous metaplasia resembling that of skin. Immunohistochemistry revealed positive immunoreactivity of the tumour cells for vimentin, S100 and melan-A, confirming the diagnosis of uveal melanoma. This finding should be included in the differential diagnosis of ocular tumours causing glaucoma in goats.