Narcoleptic horses

["C.M.Newell" <reshan@deyr.ultranet.com>]

There's a physostigmine challenge test for narcolepsy in horses--you inject
it, and the positive horse will fall asleep.
It is possible to treat with imipramine (a tricyclic antidepressant), but I
don't personally know of any case in which that has been tried.

The few that I have had in my practice, fortunately, did not seem to have
episodes under saddle. They had them primarily in crossties. One was a show
horse who would fall down while being braided. 
             --CMNewell, DVM