Long-term follow-up of optic neuritis associated with meningoencephalitis of unknown etiology in a Maltese dog

A 6-year-old intact male Maltese dog presented with a history of blindness and ataxia. Neuro-ophthalmic examination revealed dilated pupils with absent pupillary light reflexes and menace response in both eyes. Mild peripapillary edema was noted in the fundus of the right eye. After magnetic resonance imaging, the dog was provisionally diagnosed with meningoencephalitis of unknown etiology. Follow-up funduscopy was performed to monitor the condition of the optic discs for three years. Despite of the treatment with prednisolone, the optic nerve progressed to atrophy and the dog couldn’t restore vision.