Congenital feline spongiform encephalopathy

© Salvadori, CS, et al (2007) Spongiform neurodegenerative disease in a Persian kitten. Journal of feline medicine and surgery. 9:242-245

Spongiform change in the central nervous system can involve the grey or white matter, or both, and is characterised by the presence of vacuoles in the myelin sheaths, in the dendrites or axons in the neuropil or by swelling of astrocyte or oligodendrocyte cytoplasm.

Congenital spongiform degeneration of the grey matter has been described in cats and a suspected inherited encephalomyelopathy characterised by spongy change in the grey matter and Wallerian degeneration in the spinal cord has also been described in five related Birman kittens. Transmissible spongiform encephalopathies cause spongiosis in humans and animals and feline spongiform encephalopathy (FSE) has been recognised since 1990.

Common clinical signs are ataxia, abnormal behaviour, hyperaesthesia, and altered grooming. The presence of fibrils similar to those described in scrapie or bovine spongiform encephalopathy has also been described.

Spongiform degeneration of the white matter has been reported in two Egyptian Mau kittens with widespread vacuolation throughout the brain and spinal cord. The most severely affected areas were the cerebral subcortical, subependymal and cerebellar white matter, midbrain and brain stem. Similar lesions have also been described in cats with experimental bromethalin toxicosis. Grey and white matter spongiform degeneration has also been described in several dog breeds.

Congenital spongiform encephalopathy in cats can be differentiated from thiamine deficiency because thiamine deficiency is typically associated with bilateral and symmetrical petechial haemorrhages and oedema involving caudal colliculi, lateral geniculate and vestibular nuclei.

Congenital spongiform encephalopathies can be differentiated from FSE because of;

1. early onset (spongiform encephalopathy-affected cats usually under 6 months of age

2. location of lesions (spongiform encephalopathy usually affects cerebral cortex, cerebellum, and visual and vestibular nuclei, and some brain stem nuclei, whereas FSE usually affects medial geniculate nucleus, thalamus and corpus striatum, raphe nucleus, vagus nerve and red nucleus.

3. negative prion test (PrP-res immunolabelling)

The age of the animal, the early onset of neurological signs and the characteristic lesions are suggestive of a congenital form of encephalopathy.

Spongiform encephalopathy in the brain