Recently we visited our friend Emily and Morgan, who is now 20 years old. Morgan was always a robust mare who was considered an “easy keeper,” and it was important to keep close watch on her diet to be sure she didn’t gain extra weight.
However, Emily had noticed over the past couple of months that Morgan had been having difficulty building muscle along her topline and hindquarters and had been losing weight. She also had shifting or alternating leg lameness and her feet were tender, causing Emily to decide to have her tested. Her scans indicated that she needed treatment for Lyme disease.
It seems as though there is an increasing number of diagnosed cases of Lyme disease, both in humans and animals. There has been an abundance of ticks, the primary transmitters of the disease, seemingly year-round. Ticks thrive when they are exposed to moisture and humidity – such as in early spring, summer and late autumn, which puts horses at the greatest risk during these seasons, especially during wet weather.
However, as temperatures rise due to climate change, the number of cases of Lyme disease is now rising even during winter months in the Northeast. Changes in seasonal temperatures and the amount of precipitation from year to year affect the rate of occurrence of Lyme disease. And not only is the rising tick population concerning, in addition, one of their primary hosts, the white-footed mouse, also seems to be more prevalent.
The causative bacterium of Lyme disease is Borrelia burgdorferi, which is carried by the blacklegged tick (also known as the deer tick or Ixodes tick) while feeding on a host, such as the white-footed mouse and white-tailed deer. The tick then attaches itself to another animal or human and transmits the bacteria via the bite.
Lyme disease in horses can cause lameness (sometimes lameness that shifts from foot to foot), muscle tenderness, swollen joints, weight loss and low-grade fever. It can also cause skin sensitivity, depression and changes in behavior. Unfortunately, Morgan had exhibited a few of these indicators; and the weight loss over just a couple of months was very apparent, as her ribs were starting to show.
In addition to adjusting her feed to help her to gain some weight, Emily added stabilized rice bran to Morgan’s breakfast and dinner. She started Morgan on DGL complex, teasel root and knotweed tinctures to help with the Lyme disease as well.
As Morgan has always been barefoot, Emily used glue-on silicone shoes to help her to feel more comfortable, which has really helped with the lameness. She also put bell boots on Morgan’s front feet, as she sometimes overreaches with her hind feet. When we visited, she was moving around comfortably and appeared to be happy and content.

Morgan seems happy and content, as evidenced by the look in her eyes and her good nature, but her weight loss due to the Lyme disease is apparent. She is wearing glue-on silicone shoes and bell boots, which have greatly helped her lameness issue. Photo by Judy Van Put
Although a Lyme vaccine has been approved for use in dogs, there is still not an approved Lyme vaccine for use in equines. In some areas where Lyme infections are prevalent, veterinarians have used the canine vaccine on horses with some success. Cornell University has conducted trials on this subject that revealed that vaccinating horses with the canine vaccine can stimulate the production of antibodies in some horses, but those responses varied, and the effects were often short-lived.
The best method of helping your horse avoid Lyme disease is prevention: diligence in grooming and inspecting your horse on a daily basis. When grooming, pay special attention to the areas under the jaws, along the jawline, in the ears, around the mane and inside the legs. Keep a tick remover with your grooming materials. We used a “tick pick” that was very effective in removing a number of ticks. It basically lifts the tick up off the skin without squeezing, as tweezers can do. Squeezing the body of a tick with tweezers can be counter-productive, as it can push its infected blood down into the horse’s bloodstream.
It takes from 16 to 24 hours for an embedded tick to transmit the bacteria that cause Lyme disease, so you should remove any ticks you may find immediately, even after it has bitten, in order to reduce your horse’s risk of developing the disease.
Keep your pastures mowed and trim weeds around your barn and the outbuildings your horse frequents to five inches or less. Ticks will crawl up tall grasses and shrubs and will transfer onto any animals that brush past; by keeping vegetation in your horse’s living area and turnout short, you will help prevent exposure to ticks. It’s important to do a close inspection of your horse for ticks after bringing it in from the pasture or after a trail ride.
Another aid in limiting the number of ticks from your property is to keep a flock of free-ranging chickens or guinea hens, which are known to help keep ticks under control. Fly predators, which are sold online by a number of companies, have also been proven to reduce the numbers of biting insects from your pastures and paddocks.
Read the label on your horse’s fly repellants to be sure they are effective against ticks as well. Use of a tick repellent on a daily basis, as directed on the label, is helpful. Pay close attention to the legs, head, under the jaw, mane, belly and tail. Ticks can continue to bite even after the first few frosts, when flies and mosquitoes have gone; you should continue to apply tick repellents until temperatures remain below freezing.
If you have a dog that frequents the barn, be sure to use a tick repellant on your dog and keep a close eye on grooming and removing ticks from your dog as well.
Being diligent in your horse’s daily observation and grooming, including applying tick repellent and keeping up preventive methods in and around your pastures and barn, will lessen the chances of your horse being exposed to Lyme disease.
by Judy Van Put
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