Adult-onset cerebellar cortical abiotrophy and retinal degeneration in a domestic shorthair cat

A 4-year-old, neutered male domestic shorthair cat presented for evaluation of ataxia and visual deficits. Neurological examination revealed severe cerebellar ataxia with symmetrical hypermetria and spasticity, a coarse whole-body tremor, positional vertical nystagmus, and frequent loss of balance. A menace response was absent bilaterally, and the pupils were widely dilated in room light. A funduscopic examination revealed markedly attenuated to absent retinal vessels and pronounced tapetal hyperreflectivity, findings consistent with end-stage retinal degeneration. Blood work evaluation included retroviral testing, a complete blood count, serum biochemistry analysis, taurine levels, and toxoplasma immunoglobulin G and immunoglobulin M titers. All were within reference ranges. The patient was euthanized, and a necropsy was performed. Microscopically, lesions of the nervous system were confined to the cerebellum and were consistent with cerebellar cortical abiotrophy. Selective photoreceptor degeneration was seen on histopathological examination of the retina with a reduction in the number of rods and cones. The combination of clinical findings and histopathological lesions seen here has not been previously reported in the cat.