Arnold-Chiari malformation and associated anomalies in calves.

The Arnold-Chiari malformation is described in 10 calves. Eight of them had internal hydrocephalus and/or spina bifida and two occurred as a single isolated defect without associated anomaly. Malformation of the base of the skull and large foramen magnum appeared to indicate that the abnormal embryonic development of the neural tissue and basal bone may contribute to the development of the Arnold-Chiari malformation in cattle.