lyme disease in horses

Horse owners and veterinarians alike have good reason to loathe Lyme disease. In horses, its notoriously difficult to diagnose and has (or might not have) a myriad of vague (or not-so-vague) clinical signs. And those clinical signs? They often don’t appear until months following disease transmission from an infected tick.

Researchers are still working to find the most effective ways to diagnose Lyme disease. What’s more, treatment—though often eventually effective—can be expensive and time-consuming to administer. In short, it can be a confusing and costly ride for owners of affected horses.

But here’s some good news: We’ve compiled 10 resources to help you get and stay up to speed on Lyme in case you’re ever faced with an infected horse. Find more information by searching “Lyme disease” or visiting the “Lyme Disease” page on

ARTICLE: Equine Lyme Disease: What You Need to Know Learn how horses contract Lyme disease, what clinical signs to watch for, how to treat it, and more. Read More

VIDEO: I Think My Horse Has Lyme Disease: Now What? Dr. Amy Johnson of Penn Vet’s New Bolton Center offers advice on what to do (and not to do) if you suspect your horse has contracted Lyme disease. Watch Now

ARTICLE: How to Protect Horses From Lyme Disease Some ticks can carry and transmit the bacterium that causes Lyme disease to horses. Here’s what you should remember. Read More

ARTICLE: Does a Canine Lyme Vaccine Elicit a Response in Horses? We have at our disposal vaccines designed specifically for horses to help prevent many common ailments, from West Nile virus and Eastern equine encephalitis to strangles and influenza. But one equine vaccine that remains elusive is that against Lyme disease. There is, however, a canine vaccine that many veterinarians use off-label for horses in Lyme-endemic areas. But to date, there have been no studies evaluating this product’s impact on horses’ humoral (blood) immune responses. So, researchers recently evaluated how 42 healthy horses’ bodies reacted after being vaccinated with the canine product. Read More

ARTICLE: Advancements in Equine Lyme Disease Testing An accurate diagnosis is key to implementing a successful treatment plan for any condition. But for many years, veterinarians were faced with subpar testing options when it came to diagnosing Lyme disease in horses. Recently, however, researchers have developed several new diagnostic options that are proving beneficial for diagnosing this tick-borne disease. Read More

ARTICLE: Getting to the Bottom of Equine Lyme Neuroborreliosis Equine Lyme disease can be challenge for veterinarians to diagnose, not only because of its variable clinical signs, but also because not all “infected” animals develop disease. Even more challenging is Lyme neuroborreliosis (NB), which occurs when the causative agent—Borrelia burgdorferi—infects horses’ nervous tissue. Not every horse infected with B. burgdorferi will develop NB; many horses show no signs of disease. And, even if they do, there’s no reliable way to diagnose it. Read More

ARTICLE: Diagnosing Lyme Neuroborreliosis in Horses is Difficult Most horses in the Mid-Atlantic region show evidence of exposure to B. burgdorferi, the bacterium that causes Lyme disease. Most exposed horses don’t develop clinical signs of disease. However, a small number of infected horses will develop disease of the nervous system, termed Lyme neuroborreliosis. Diagnosis of equine Lyme neuroborreliosis is often elusive and the disease provokes more questions than answers: What signs do horses with Lyme disease show? What test can be used to diagnose the disease? How should test results be interpreted? Read More

FARM CALL: Is My Horse a Tick Magnet? I have two geldings, a dark bay and a chestnut, that were turned out together for about two months. When I brought them back to the barn, the dark bay was covered in what seemed like hundreds of deer ticks. The chestnut maybe had five ticks. Why would there be such a difference in tick numbers if they were in the same pasture? Read the Answer

ARTICLE: Tick-Borne Disease: Tremendously Tricky in Horses If the sight of a tick makes your skin crawl—even if it’s not crawling on your skin— you’re not alone. That feeling is founded on more than a natural aversion to arachnids; diseases transmitted by ticks can pose a real health threat. With Centers for Disease Control and Prevention maps outlining tick ranges throughout most the United States, it’s important we brush up on our understanding of tick-borne diseases. In this article we’ll look at the three that pose the biggest risk to horses: Lyme disease, anaplasmosis, and piroplasmosis. Read More

ARTICLE: Testing for EPM, Lyme, and Other Equine Neurologic Diseases A neurology specialist reviews the confusing landscape of laboratory diagnostics for neurologic disease in live horses. Read More