Two previously healthy 14-year-old horses developed right-sided unilateral
vestibular signs after they had possibly been struck by lightning. Repeated
radiographic and endoscopic evaluations did not reveal any significant cha
nges. A brainstem auditory evoked response test indicated a subtle left to
right interaural latency difference of waves I, III and V in the more sever
ely affected pony, but its central conduction time remained normal.