Congenital cerebellar hypoplasia in newborn calves.

A sporadic outbreak of congential cerebellar ataxia (CCA) was seen in calves. The abnormality of this disorder of the central nervous system characteristic was cerebellar hypoplasia, which was observed in eight calves. The cerebellum was almost completely absent in some of these calves and approximately one-fifth of the normal size in some others. Six of the eight calves were also affected with hydrocephaly. The significant changes of the cerebellum were complete or partial destruction of the cortex, deficiency of granules and/or Purkinje cells, clumping of the remaining granule cells, and an irregular cavity formation in the terminal portion of the folium. The clinicopathological changes of CCA quite closely resembled those of the bovine viral diarrhea-mucosal disease virus infection.