Just yesterday, a working student in our barn noticed a couple of scabs embedded in the mane of a horse she was bathing. Concerned by the appearance of the lumpy, puss filled scabs, she came to me asking for advice on what they were and how to treat them. Upon further examination, we found two ticks in the horse’s mane. It’s that time of year again; the season when the grass is growing, the flowers are blooming, the horses are shedding, and the ticks are appearing.
Tick season is upon us, and with the appearance of ticks comes the concern for Lyme Disease. This disease that can so vigorously affect our horses’ well-being is also the variety that has been known to affect humans and dogs. While there is no vaccine to prevent the disease in horses, there are several precautions that can be taken to guard against its effects. Knowledge is often the best prevention and knowing the disease, its causes, symptoms, and treatment is the best defense in providing protection for our horses.
Lyme disease is caused by the bacteria Borrelia burgdorferi (B. burgdorferi) which is carried by a species of tick most commonly known as deer ticks. These ticks are almost exclusively found in the northeastern and midatlantic states, including Connecticut, Rhode Island, New York, Pennsylvania, Delaware, New Jersey, Maryland, Massachusetts as well as some areas of Wisconsin. Baby ticks “nymphs” are usually found beginning in May, and can sometimes be difficult to find on a horse because of their small size. The earliest cases of Lyme Disease are often diagnosed at this time of year, and new cases continue to be diagnosed into the mid to late summer, as ticks grow in size and prevalence. In some cases, symptoms do not appear until several months after a horse has been exposed to the bacteria.
Horses that have contracted Lyme Disease often show varying symptoms, depending upon which system of the horse has been affected. Signs and symptoms often include neurologic impairments, chronic weight loss, low-grade fever, sporadic or shifting leg lameness, muscle tenderness, and arthritis. Other more non-specific symptoms may include behavioral changes, poor performance, and skin hypersensitivity. Because many of these symptoms are often shared with other conditions and diseases, Lyme Disease is sometimes very difficult to diagnose (Loving, 2013).
Diagnosis for this disease is made with a blood test, which tests for the presence of antibodies in the bloodstream, indicating that the horse has either been exposed to the disease or has been vaccinated for it. While there is currently no equine vaccine for the disease, some veterinarians are using a vaccine that has been approved for dogs. There are reportedly fewer cases diagnosed among horses that have been vaccinated with the canine vaccine; but contrarily, diagnosis of symptoms in a horse that has received this vaccine can be difficult (Hicks, 2013). No clinical research has been published regarding the use of the canine vaccine in horses.
Because there is no approved equine vaccine for Lyme Disease and the protection provided by the canine vaccine is sketchy at best, the most ideal defense against the disease is prevention. The bacterial levels that cause Lyme Disease usually accumulate to concerning levels in the horse’s bloodstream after two days of an infected tick embedding itself on the horse. Therefore, the best prevention against the disease is thoroughly grooming and going over your horse every day to assure that any embedded ticks are caught and removed early. Some horse owners rely on fly sprays that have been marketed to guard against ticks, which do probably deter these insects to some extent. However, they are no substitute for hands on care and attention to detail of your horse. Ticks will attach themselves anywhere on your horse’s body, but are most commonly found along the edge of the tail where the hair meets the skin, in the mane, under the throatlatch, around the ears, under the belly or on the underside of the neck. These are areas where your horse cannot easily rub the ticks off of himself.
Other indirect prevention measures against the disease include controlling the mice population in and around your stable, as mice carry the bacteria B. burgdorferi, which are then transmitted by ticks. Furthermore, mowing pastures to about five inches in length will deter ticks from climbing tall blades of grass and attaching themselves to your horse’s legs (Carter, 2013). In any case, it is always best to talk with your veterinarian about specific measures that you can take to provide the best prevention for your horse.
If your horse is showing symptoms of Lyme Disease, it is best to consult your veterinarian, who can perform a blood test. If your horse has been diagnosed, treatment most commonly involves a month of antibiotics (doxycycline) which come in the form of tiny pills, most easily administered in your horse’s feed. Follow up blood tests are performed after several weeks to determine the effect of the antibiotics, which have hopefully served their purpose of decreasing the bacterial population in the bloodstream.
While Lyme Disease can be bothersome and debilitating, it is not directly contagious among horses, eliminating the need for quarantine of an infected horse. Thankfully, the disease is not usually fatal in horses and an infected horse is able to return to full work and function after successful treatment.
So when you are out enjoying the beautiful Spring weather and appreciating the fact that the flies have not yet appeared in full force, don’t forget that there are other pesky insects that can harm your horse and be sure to take steps to prevent Lyme Disease from causing problems in your barn.
Carter, B. (2013, May 3). Take steps to limit ticks near the stall. The Free Lance-Star.
Retrieved from news.fredericksburg.com
Hicks DVM, T. (2013). Lyme disease. Equine Vet Services.
Retrieved from equinevetservice.com
Loving, N. (2013, March 17). New test could detect equine lyme disease sooner. Bloodhorse.com.
Retrieved from bloodhorse.com