A 6-year-old neutered female Boston Terrier had a slow onset of blindness and behavior changes. Neurologic abnormalities included bilateral visual loss with absent menace responses and visual tracking, mydriatic pupils, slow pupillary light responses and papilledema. On magnetic resonance imaging (MRI) there were multiple cyst-like structures found in the parenchyma of the cerebrum, cerebellum and brainstem. Histopathologically the diagnosis was a choroid plexus carcinoma with meningeal carcinomatosis. The findings differ from previous descriptions of the MRI characteristics of choroids plexus tumors.