A two-year-old male cat with acute neurological symptoms of unknown cause, such as paralysis of the four limbs, was examined by magnetic resonance imaging (MRI), and treated with medicine successfully. The MRI scan showed abnormal findings including high density on T2-weighted and flare images in areas ranging from the right midbrain to the left brainstem and from the left cerebrum to the cerebellum. These findings indicated the presence of extensive cerebral edema. Taking into consideration the cat's medical history and the acuteness of its clinical signs, other possible diseases were excluded, and a tentative diagnosis of feline ischemic encephalopathy was made. Treatment with glycerin and a corticosteroid improved the clinical problems, and the cat appeared normal by day 8. There was no recurrence until the cat was killed in a car accident one year later.