Congenital spongiform change in the brain stem nuclei of a domestic kitten.

This report describes a novel spongiform change in the brain stem nuclei of a 9-month-old mixed breed kitten with neurological signs. Histologically, vacuoles were found in perineuronal spaces and neuropil, with mild to moderate astrocytosis in the brain stem nuclei. Vacuoles were not observed in the cytoplasm of neurons and no evidence of neuronal loss was found. Ultrastructurally, there were intramyelinic vacuoles with separation of lamellae at intraperiod lines and larger spaces formed by coalescence of ruptured vacuoles. Immunohistochemically, abnormal accumulation of prion protein (PrP) was not detected in the brain stem lesions. This is, to our knowledge, the first report of a feline spongiform change localized in the brain stem nuclei.