Spring has sprung … and so have the ticks. With some of those ticks comes the risk of your horse contracting Lyme disease, an infection caused by the bacterium Borrelia burgdorferi.

Lyme disease is transmitted mainly via Ixodes ticks, which pass the bacteria from infected animals to uninfected animals during feeding. The bacteria have been identified in other tick species, as well, but it is unclear whether they can transmit infection.

Signs of Lyme disease in horses are nonspecific and include lethargy, a stiff gait, hyperesthesia (hypersensitivity to touch and sound), muscle wasting, ataxia (incoordination), nerve and muscle pain, nodular dermatitis (bumps on the skin that can be associated with crusting, oozing, and infection), and uveitis (inflammation of the eye’s uvea). Once a veterinarian diagnoses a horse with Lyme disease (more on this is a moment), he or she can prescribe antibiotics (tetracycline, doxycycline, and minocycline being the most common), but these are expensive because the treatment period is long-term.

“The ‘perfect’ treatment schedule in terms of dose, frequency, and duration of treatment are not currently known, but a common approach is to administer intravenous tetracycline twice daily for seven to 10 days, then oral doxycycline or minocycline twice daily for one to two months,” said Tom Divers, DVM, Dipl. ACVIM, ACVECC, Steffen Professor of Veterinary Medicine and section chief of large animal medicine at the Cornell University College of Veterinary Medicine, in Ithaca, New York. Veterinarians can use both a clinical response (decrease in clinical signs) and serologic response (decrease in antibody titers) to further guide treatment plans