Congenital hydranencephaly and cerebellar hypoplasia in calves.

Hydranencephaly with marked cerebellar hypoplasia was diagnosed in 4 calves in a 95-cow herd in British Columbia, Canada. Clinically, these cases were similar to 8 earlier cases on the same farm. Affected calves were born weak, had slightly domed foreheads, and were incoordinated and thus unable to suckle their dams; at least 2 had no eye preservation reflex. The condition was reported to have been common in the Fraser River Valley during the 1973/1974 calving season. Serologic investigations of the dams were negative for bluetongue and infectious bovine rhinotracheitis. An environmental rather than inherited cause was postulated.