Neuronal vacuolation in an adult ferret.

The brain of a ferret showing abnormal neurologic signs was evaluated by histopathologic, histochemical, immunohistochemical, and ultrastructural examinations. Extensive neuronal vacuolation was observed. Since the brain was negative for protease-resistant protein prion (PrPres), it was concluded that this was not a case of transmissible spongiform encephalopathy.