Merck Manual

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Miscellaneous Congenital Disorders of the Nervous System


Rebecca A. Packer

, MS, DVM, DACVIM (Neurology), College of Veterinary Medicine and Biomedical Sciences, Colorado State University

Last full review/revision Jul 2013 | Content last modified Jul 2013

Large Animals

Pendular nystagmus is seen in various breeds of dairy cattle but appears to have little clinical significance.

Congenital deafness has been reported in horses.

Small Animals

Pendular nystagmus is seen in various breed of Asian cats but appears to have little clinical significance. Compared with pathologic forms of nystagmus, in pendular nystagmus there is no fast or slow phase, and the nystagmus arcs are similar to the pendulum movement of a clock.

Congenital deafness is primarily associated with Dalmatians but has also been recorded in a number of breeds, including Australian Blue Heelers and Shepherds, English Setters, Boston Terriers, and Old English Sheepdogs. It is linked to blue eye color in white cats. The brain stem auditory evoked response (BAER) is a useful diagnostic test primarily used to identify carriers in a litter of affected animals. (Also see Deafness.)

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