Onchocerciasis in two dogs.

Although widely reported in cattle, horses, and other ungulates, onchocerciasis has only recently been reported in 1 dog. We report 2 additional dogs with onchocerciasis involving the palpebral conjunctiva, third palpebra, and sclera. Both dogs were evaluated because of ocular or periocular masses. Histologically, viable adult parasites were surrounded by minimal fibrosis and few macrophages. Pyogranulomas were often centered around degenerating or mineralized Onchocerca organisms. Onchocerciasis should be considered in the differential diagnosis of ocular or periocular nodules in dogs, particularly dogs from western states.