Pendular nystagmus in dairy cattle.

In a survey of 2,932 mature dairy cattle performed over a 1-month period, we found 15 with rapid oscillation in 1 or both eyes. Nystagmus had been present since shortly after birth in 2 animals, and the age at onset was unknown in the others. The nystagmus was not associated with any other physical or neurologic problem. Pendular nystagmus apparently is benign and should not be mistaken for a sign of serious neurologic disease.