If you frequently find ticks on your horse, you're probably concerned about him developing Lyme disease. This illness is transmitted via a bite from a deer tick, which spreads the Lyme-causing bacteria Borrelia burgdorferi.
Unlike humans, there's no telltale bull's-eye rash appearing in horses afflicted with Lyme disease. While your horse may prove positive for Lyme exposure via a blood test, that doesn't necessarily mean he has the disease. Most horses testing positive for Lyme disease never come down with the condition.
Temperament and Other Changes
Lyme disease is often hard to diagnose because many symptoms are subtle. A horse may exhibit temperament changes, including irritability. He might lack energy and become unwilling to work. Muscle stiffness or tenderness, lameness that moves from leg to leg, weight loss and touch sensitivity can all result from Lyme disease. The lameness may come and go. The horse may experience a low-grade fever. Because a horse may not show serious signs of illness early on, an owner might not call a vet until the symptoms become more obvious.
Trust your instincts and call your vet if your horse is "not quite right," even if you can't specify exactly what's ailing him. Once Lyme disease becomes chronic, it can include neurological, vision and joint problems.
Treating Lyme Disease
Your vet will likely prescribe long-term antibiotic therapy to treat your horse's Lyme disease. Treatment generally lasts between four and six weeks, and the antibiotic of choice is oxytetracycline. Your vet may also prescribe nonsteroidal anti-inflammatories during treatment to ease your horse's joint and muscle pains.
Lyme Disease Prevention
Currently, no equine vaccine exists for Lyme disease. During tick season -- which may encompass all the months in which temperatures are above freezing in your region -- check your horse every day for these bloodsucking parasites. Ticks may appear anywhere on the equine body, but most often take their meals on the tail base, inside the ears, on the neck and the mane's base. Apply fly repellents containing pyrethrin or permethrin to discourage ticks. Remove any ticks found on your horse with tweezers, and put them in a jar of water both to kill them and keep their remains for veterinary testing.
Around the farm, keep fields mowed -- ticks love tall grass -- and get rid of large piles of leaves or brush, both common tick hideouts.