Diseases of the central nervous system in cattle of southern Brazil.

A retrospective study was carried out on 6,021 necropsies of cattle performed over a 36-year period in southern Brazil. Of those, 552 (9.16%) presented neurological clinical signs and their necropsy protocols were reviewed to gather information on type of gross and histopathological diagnosis, etiology, and clinical signs. In 147 cases (26.63% of 552) there were no significant lesions in the central nervous system, in 79 (14.31% of 552) no samples of nervous tissue were submitted to the laboratory and in 21 (3.81% of 552) the tissues submitted were autolysed and not suitable for histological diagnosis. Lesions found in the remaining 305 cases were classific 1 as inflammatory, degenerative, circulatory, congenital, and neoplastic. The inflammatory lesions accounted for the largest category (66.89% of 305 cases). This was further divided in lesions caused by viruses (57.38% of 305 cases) and by bacteria (9.51% of 305 cases). Diseases caused by viruses were rabies (49.51% of 305 cases), necrotizing meningoencephalitis by bovine herpesvirus (4.59% of 305 cases), and malignant catarrhal fever (3.28% of 305 cases). The degenerative changes were represented by 74 cases (24.26% of 305 cases) and included status spongiosus due to liver failure induced by Senecio spp poisoning (10.49% of 305 cases) or to the direct effect of poisoning by Ateleia glazioviana (0.33% of 305 cases); cases of liver failure not associated with morphological changes in the brain (2.95% of 305 cases), myelomalacia due to cord compression (2.62% of 305 cases), primary neuronal degeneration associated with Solanum fastigiatum poisoning (2.29% of 305 cases); polioencephalomalacia (1.97% of 305 cases); tetanus (1.31% of 305 cases) and intestinal coccidiosis in calves, ketosis, and botulism with one case each (0.33% of 305 cases). Circulatory disturbances accounted for 19 cases (6.23% of 305 cases) and included cerebral babesiosis (5.57% of 305 cases) and hemorrhages due to trauma (0.66% of 305 cases). Congenital conditions represented 2.29% of the 305 cases and included cerebelar abiotrophy (two cases) and one case each of porencephaly, hypomyelinogenesis, demyelination, hydrocephalus, and cerebellar malformation. Only one neuroectodermal neoplasm (0.33% of 305 cases) was found in this series.