What is it?
Equine Lyme disease is a bacterial illness caused by the bacterium Borrelia burgdorferi. It is most commonly transmitted by the bite of infected ticks, commonly referred to as “deer ticks” or “black legged ticks”.
What are the symptoms?
Symptoms of equine Lyme disease appear in less than 10% of horses that are infected with Borrelia burgdorferi. The organism transmitted by the tiny deer tick invades the body and replicates itself in many forms. It often affects several parts of the body at the same time, causing symptoms of many illnesses and complicating the correct diagnosis. Symptoms of chronic Lyme include, but are not limited to:
Poor energy levels
Stiffness, muscle pain
Shifting leg lameness
Swelling of multiple joints
Edema or eye inflammation
Irritability, body-wide sensitivity to touch
Where does it come from?
Horses may become infected with Borrelia burgdorferi from the bite of infected ticks. Although the adult ticks are the ones we generally find most frequently on our own bodies or firmly attached to our horses, it is at the nymphal stage that Lyme disease transmission is the greatest. Lyme disease transmission is highest during May and June, which coincides with peak nymphal stages.
The correct way is to grasp the tick with fine tweezers as close to the skin surface as possible and then pull straight up with a slow, steady force. Don’t squeeze!
How is it diagnosed?
Diagnosis of Lyme disease in horses is difficult for two reasons: horses are subject to many injuries which may result in lameness similar to that seen with Lyme disease. Additionally, the blood tests used for Lyme disease diagnosis only indicates that the horse has been exposed to Borrelia burgdorferi, not that his illness is related to Lyme disease.
Some detective work may be necessary to confirm any diagnosis. Is the horse in a tick-infested area where Lyme disease has been reported? Does it show all the classic symptoms, with other diseases with the same symptoms being ruled out? Answering yes to these and other questions may help pin down the answer.
One of the best ways to determine if you or your horse is a candidate for Lyme disease is to save the tick that has done the biting and have it tested for presence of the infectious bacteria.
How is it treated?
Equine Lyme disease is treated with antibiotics. In addition to antibiotics, some veterinarians will administer anti-inflammatory drugs and/or medicines to help replace the normal intestinal bacteria killed by the antibiotics.
In a small number of animals, there may be an adverse reaction as the toxins released by the toxins released by Borrelia burgdorferi that are killed during the first few days of treatment. Symptoms be get worse for a day or two, and this may precipitate laminitis. Monitor your horse for the signs of laminitis and contact your vet immediately if you suspect it.
How is it prevented?
For horse owners in endemic areas, the most effective preventative is quick removal. Ticks do not transfer the bacteria immediately, so careful daily examination is important. Unfortunately, the nymphs may be very difficult to spot. Ticks can be found about anywhere on a horse’s body, but one should be certain to examine the area along the neck at the base of the mane and around the rectal area.
There are tick repellent products available. While they might decrease the number ticks on your horse, it is still a good idea to continue to check your horse thoroughly for ticks, even if using one of these products