Diagnosing Lyme disease in horses is tricky business; not all horses that contract the causative bacterium, Borrellia burgdorferi, from infected ticks develop the debilitating condition, and those that do might not show signs until several months after infection. As with many diseases, early detection can mean swifter resolution, along with better recovery, so Cornell researchers have been searching for reliable ways to detect B. burgdorferi sooner. Bettina Wagner, DVM, PhD, associate professor of immunology at the university’s veterinary school, described a new test she and her colleagues developed. She presented the testing protocol at the 2012 American Association of Equine Practitioners’ (AAEP) Convention, held Dec. 1-5 in Anaheim, Calif.

In North America, Ixodes ticks are responsible for transmitting B. burgdorferi to susceptible horses, which become incidental, dead-end hosts. Possible clinical signs range from chronic weight loss, low-grade fever, sporadic or shifting leg lameness, muscle tenderness, and arthritis to behavioral changes, neurologic signs, poor performance, and skin hypersensitivity, to name a few.

"Because clinical signs are rather nonspecific," said Wagner, meaning they could be attributable to a number of diseases, "Lyme disease can be difficult to diagnose in horses." It’s important for veterinarians to consider a horse’s potential for infection, such as if the animal lives in or has visited an endemic area. The eastern United States is a known hot spot for Lyme disease, but veterinarians also detect it in areas such as Florida, Texas, and California. Another indicator to help the practitioner diagnose Lyme disease is serologic testing for antibodies against B. burgdorferi.