Congenital microhydranencephalus in cattle.

Hydranencephaly with porencephalic cavitation of the cerebellum was diagnosed, over a 2-year period, in five calves from an 80-cow herd. Affected calves were blind and exhibited fine head tremors and limb rigidity. Bovine virus diarrhea-mucosal disease (BVD-MD) antigens, found in the tissues of two calves, were considered to be the likely cause.