What is your neurologic diagnosis?

An 8-year-old 6.5-kg (14.3-lb) neutered male Chinchilla-cross cat was referred to the Neurology Service at the School of Veterinary Sciences, University of Bristol, 48 hours after sudden-onset paraparesis. Initially, the cat had been unable to jump but its condition progressed to tetraparesis, most markedly on the right, during the first 24 hours following onset. The cat also became dysuric, with a large nonpainful bladder present from time of onset of paraparesis. There was no possibility of trauma or toxic exposure, and the cat did not appear to be in pain. On physical examination, the cat was overweight (body score, 6/9) but other findings were unremarkable. A neurologic examination was performed