A one year old female spayed French Bulldog presented to the Ophthalmology Service at Cornell University for evaluation of a one week history of vision loss. On ophthalmic examination, the pupils were mydriatic but responsive and the palpebral reflexes were intact OU, while the menace response and dazzle reflex were absent OU. The adnexal structures and anterior segment appeared normal. On fundic examination, the optic discs and the retina surrounding them were slightly edematous and elevated OU. An electroretinogram recorded normal retinal function, and the dog was subsequently transferred to the Neurology Service. Magnetic resonance imaging of the brain revealed swollen and T2-hyperintense optic tracts and optic chiasm that displayed marked contrast enhancement. Cytologic analysis of cerebrospinal fluid revealed a mild lymphocytic pleocytosis. The dog was presumptively diagnosed with optic neuritis caused by granulomatous meningoencephalitis (GME) and treatment was begun with an immunosuppressive dose of oral prednisone. The dog had regained some vision by her recheck examination 2 weeks later but was exhibiting side effects of the prednisone. Treatment with oral cyclosporine was added and her prednisone dosage was reduced two weeks following initiation of the cyclosporine. Three months following discharge from the hospital, the dog still retained vision which the owner reported to be at 80% from prior to her onset of blindness. Her dosage of prednisone was further tapered and the cyclosporine was continued.