PREVENTIVE MEASURES

Currently, there is no vaccine against Lyme disease approved for use in horses. However, in regions where the disease is common, some owners opt to administer the canine vaccine to their horses. Talk to your veterinarian about the risks and benefits if you want to consider this option.

Trials at Cornell University showed that vaccination with a canine product can stimulate the production of antibodies in horses, but responses varied in individual horses, ranging from weak to high, and the effects were short-lived. The typical schedule for vaccinating horses includes initial boosters at three weeks and then again at three months after the initial injection. OspA antibodies will begin to drop in less than six months, so biannual boosters are needed to achieve year-round protection in Lyme-endemic areas. No safety studies have ever been conducted for this vaccine in horses, but no adverse effects have been reported.

Apart from the canine vaccine, the best defense against Lyme disease is to limit your horse’s exposure to ticks:

• 2EMOVE TICKS FROM YOUR HORSE DAILY. As you groom your horse each day, check all the “secluded” places where ticks like to hide, such as the ears, under the jaw, under the mane and inside the legs. Keep a pair of tweezers on hand while you groom. If you find a tick that has latched on, you’ll want to remove it carefully: Grasp it gently at the head, as close as possible to the horse’s skin, and lift it straight up. Do not squeeze the body of the tick---this may push disease-causing agents down into the horse’s bloodstream.

Removing ticks daily, even after

they have bitten, will help reduce your horse’s risk of Lyme disease. Studies have shown that it takes 16 to 24 hours for a feeding tick to begin transmitting B. burgdorferi to its host.

• !PPLY REPELLENTS WISELY. Look for products that are labeled for use against ticks as well as flies and other pests. As you apply them, be careful to protect parts of the horse’s body where ticks are likely to climb on---the legs, head and neck, belly and tail.

Remember that ticks can continue biting well after flies and mosquitoes have started to die off in the fall months. Continue applying repellents to your horse until temperatures drop below freezing.

• 0ROTECT YOUR DOG WITH REPELLENTS TOO. Your dog can be vaccinated against Lyme disease, which is a wise precaution in endemic areas. But it’s a good idea to apply tick repel-

Lyme disease in the United States in 2016: Each blue dot on the map represents one human case of Lyme disease reported to the Centers for Disease Control and Prevention in 2016. (This map excludes data from Massachusetts.) The disease is most commonly seen in the Northeast and upper Midwest, although isolated cases appear throughout the United States, with clusters on the West Coast and in the South. Each dot is placed in the patient’s county of residence, but that doesn’t necessarily mean the person was exposed to the disease there—people may have become infected while traveling through endemic areas. Still, even a small cluster of blue dots in your area could be an indication that your horse may be at risk.

Ixodes pacificus Ixodes scapularis