Encefalopatia hereditária em bovinos no Estado do Espírito Santo

The epidemiological, clinical and pathological aspects of a neurological disease have been described in cattle in the Ecoporanga county, northeastern Espírito Santo, Brazil. This disease of the central nervous system occurred only in daughters of a 5-year-old Nelore bull crossed with Nelore x Quianini cows. The clinical signs, which were detectable immediately or in the first weeks after birth, are characterized by ataxia, instability, circling, abnormal position of the limbs when standing or walking (removal and/or deviation of members from the normal position) and lateral deviation of the vertebral column (main axis of the body in diagonal). The disease is expressed by variable widths in their clinical manifestations. Most affected animals died due to incapacity of milk or food intake. The macroscopic examination shows variable degree of asymmetric sectorial depressed areas of the frontal and temporal telencephalic cortex, and in the cortex of the cerebellum, as well as correspondent muscular (appendicular) atrophy. Histological examination revealed that the depressed areas are due to the sectorial reduction of neuronal populations (probably atrophy/abiotrophy), mainly in the frontal and temporal brain lobes, and in the molecular and granular layers of the cerebellar cortex. Morphometric, immunohistochemical and ultrastructural studies are underway and should provide more information about the microscopical and pathogenetic aspects. Epidemiological data indicate that the illness is directly linked to the chromosome X, with complete penetration and variable expressiveness.