RABIES-INDUCED SPONGIFORM CHANGE AND ENCEPHALITIS IN A HEIFER

A 1-year-old mixed breed heifer was presented to the Veterinary Medica l Teaching Hospital at the University of Illinois with a 3-day history of abnormal mentation and aggressive behavior. Based on the history a nd clinical examination, euthanasia and necropsy were recommended. The differential diagnoses included rabies, pseudorabies, and a brain abs cess. The brain was removed within 60 minutes of death, and the sectio n submitted for fluorescent antibody testing was positive for rabies v irus antigen, Residual brain tissue was immersion fixed in 10% neutral buffered formalin. Histologic examination revealed a marked perivascu lar and meningeal lymphocytic meningoencephalitis and locally extensiv e spongiform change of the gray matter affecting the neuropil and neur on cell bodies. The most severely affected regions with spongiform cha nge were the thalamus and cerebral cortex. No Negri bodies were found in any sections. Since the outbreak of bovine spongiform encephalopath y (BSE) in the United Kingdom, there has been an increased surveillanc e of bovine neurologic cases in an effort to assess if BSE has occurre d in the USA. In areas where rabies virus is endemic, rabies should be included as a possible differential diagnosis in cases of spongiform changes of the central nervous system.