Validity of spinal cord examination as a substitute procedure for routine rabies diagnosis

A significant portion of specimens received by this laboratory for rabies diagnosis is unsatisfactory for testing due to decomposition of the brain, or severe mutilation of the head when the animal was killed. Examination of the spinal cord was therefore explored as a possible alternative method when standard brain examination was not possible. In this study, both brain and spinal cord of 248 rabies-suspect animals were examined to assess the reliability of the spinal cord method. Brain and spinal cord of the 248 animals were examined by fluorescent antibody (FA) method, and mouse inoculation tests were performed on 247 brain specimens and 13 spinal cord specimens. By using both brain and spinal cord, 30 animals representing 8 species were diagnosed as rabid by FA, and 218, representing 11 species, were negative. There was 100% agreement between two procedures with FA as the criterion. This study showed that in cases where the usual examination is precluded due to brain destruction, the spinal cord procedure offers an equally reliable alternate method of diagnosis.