Narcolepsy in a Brahman bull

Behavioral, electrophysiologic, and pharmacologic tests were performed on a 2 1/2-year-old Brahman bull suspected of having narcolepsy. Placement on a tilt table or electroejaculation induced apparent sleep and cataplexy. Electrophysiologic recordings during the episodes revealed the low-voltage, high-frequency electroencephalogram, reduced electromyogram amplitude, and rapid eye movements in the electrooculogram associated with rapid eye movements sleep. Physostigmine salicylate appeared to elicit and potentiate the episodes, whereas atropine sulfate and imipramine reduced or blocked them. The combined results of the tests supported the diagnosis of narcolepsy.