Lyme disease in horses is caused by a bacteria in the spirochete family Borrelia burgdorferi. Transmission of this bacteria occurs through the bite of an infected black-legged deer tick. Of many of the tick diseases, Lyme disease presents the most challenges to the veterinarian and the horse owner because the symptoms of Lyme disease can be vague and mimic other neurologic diseases. In addition, there is not a clear and concise method to test for this disease and the treatment can be expensive.
Symptoms can include: depression and an altered mental state including aggression, fever, encephalitis and lethargy. Gait abnormalities can include back and neck pain, toe-dragging, ataxia, tremors and recumbency. Your horse may have an unexplained weight loss. Eye problems may include an uveitis and your horse may experience facial paralysis with drooping eye lids and lips. Occasionally, death may occur before the diagnosis is accurately determined.
DIAGNOSIS: Blood testing including serology can be the more reliable method to determine if your horse has Lyme disease. Because a horse may be positive on serology yet show no symptoms of the disease makes an accurate diagnosis challenging. Alternately, a horse may be symptomatic yet confirmed negative on serology. Often, other neurologic diseases that mimic Lyme disease may need to be ruled-out before Lyme disease is suspected.
TREATMENT: Treatment options include appropriate antibiotics such as Doxycyline and an addition of Vitamin E to the diet.