AAEP Infectious Disease Guidelines: Borrelia burgdorferi infection and Lyme disease

Infection with Borrelia burgdorferi, the Gram-negative spirochete bacterium that causes Lyme disease, is common in horses residing in regions endemic for Ixodes spp. ticks, and infection prevalence is likely on the rise as tick vectors undergo range expansion. While many horses will become infected with B. burgdorferi following a tick bite, the percentage of horses that will go on to develop Lyme disease is unknown.

At this time, documented syndromes attributed to B. burgdorferi include neuroborreliosis (ataxia, atrophy, cranial nerve deficits, stiff neck, cutaneous hyperesthesia), cutaneous pseudolymphoma (dermal masses at the site of tick bite), and uveitis (blepharospasm, epiphora, yellow-green fibrinous aqueous flare).