Immunohistochemical study of PrPSc distribution in neural and extraneural tissues of two cats with feline spongiform encephalopathy

Histopathological examination revealed a diffuse vacuolation of the grey matter neuropil with the following areas being most severely affected: corpus geniculatum medialis, thalamus, gyrus dentatus of the hippocampus, corpus striatum, and deep layers of the cerebral and cerebellar cortex as well as in the brain stem. In addition, a diffuse glial reaction involving astrocytes and microglia and intraneuronal vacuolation in a few neurons in the brain stem was present.Heavy PrPSc immunostaining was detected in brain, retina, optic nerve, pars nervosa of the pituitary gland, trigeminal ganglia and small amounts in the myenteric plexus of the small intestine (duodenum, jejunum) and slightly in the medulla of the adrenal gland.The PrPSc distribution within the brain was consistent with that described in other FSE-affected cats. The pattern of abnormal PrP in the retina corresponded to that found in a captive cheetah with FSE, in sheep with scrapie and was similar to nvCJD in humans.Feline spongiform encephalopathy (FSE) is a prion-induced disease affecting the cat family felidae. FSE belongs to the group of transmissible spongiform encephalopathies (TSE) occurring in humans and other animal species. The first report was from a Siamese cat [1]. To date, 89 cases of FSE have been reported in domestic cats in Great Britain, one in Northern Ireland, one in Liechtenstein (DEFRA) [2], one in Norway [3], one in Italy [4] and one in Switzerland [5]. In addition, spongiform encephalopathies have been described in other feline species including cheetahs, pumas, ocelots, tigers and lions (DEFRA) [2]. The disease is characterized by progressive onset of clinical signs including abnormal behaviour such as increased timidity or aggression, ataxia and hyperaesthesia. The main histopathological lesions are vacuolation of the neuropil in the grey matter of the brain and spinal cord (also referred as spongiosis), vacuolation of neuronal perikarya, and a diffuse astrocytic reaction [6,7]. Le