DISTRIBUTION OF NEOSPORA-CANINUM WITHIN THE CENTRAL-NERVOUS-SYSTEM AND OTHER TISSUES OF 6 DOGS WITH CLINICAL NEOSPOROSIS

Six cases of neosporosis in dogs were diagnosed on the basis of clinic al signs, serology and immunohistochemistry. The brains and spinal cor ds, at several levels, and various other tissues were examined using a nti-Neospora caninum serum by an immunoperoxidase technique. Parasite density varied markedly from case to case. Although found most consist ently in the cerebrum, parasites were distributed throughout the centr al nervous system (CNS), both within the grey and white matter and wit hin nerve roots. Clinical signs were not related to the position of pa rasites. Tissue cysts were found infrequently in all areas of the CNS, but not in other tissues. Parasite density was not related to the age of the dog or whether treatment had been given. However, with the exc eption of the only adult dog examined, more CNS parasites were found i n dogs with a longer duration of illness and with higher antibody titr es. Tachyzoites were present in skeletal muscles, in the muscularis of the oesophagus, in heart, lung and, less frequently, liver, and rarel y in the adrenal gland, thyroid gland and uterus; no clinical signs we re seen resulting from damage to these organs. Parasites were not obse rved in lymphoid tissue. In visceral organs, parasites were most widel y distributed in peracute cases. For post mortem diagnosis of neosporo sis, the CNS, particularly the cerebrum, is the optimum tissue to exam ine but parasites may also be found in many other tissues, especially in acute cases. Muscle biopsy of appropriate muscles (as suggested by the clinical signs) provides the possibility of a definitive premortem diagnosis.