Current tests for Borrelia burgdorferi, a tick-borne spirochete (a spiral-shaped bacterium) that causes Lyme disease in people, horses, dogs, cats, and cows, often take several days to complete and can sometimes lack definitive answers for owners and veterinarians. Researchers looking to find a reliable in-house test for B. burgdorferi evaluated a SNAP ELISA (enzyme-linked immunosorbent assay) test–which tests for antibodies against the spirochete–that IDEXX commercially markets for dogs.

“Our data indicate that the canine in-house ELISA (SNAP) test can be used to diagnose B. burgdorferi infection in horses,” said Amy Johnson, DVM, a large animal internal medicine resident at Cornell University’s College of Veterinary Medicine. She said the test had a high specificity and sensitivity in her presentation at the 2006 American Association of Equine Practitioners Convention held Dec. 2-6, 2006, in San Antonio, Texas.

“Over the last 15 to 20 years, B. burgdorferi infection in horses has been increasingly recognized, especially in some areas of the country such as the Northeast,” Johnson said. “However, clinical signs attributed to infection can be quite vague and variable. Clinical signs generally include muscle stiffness, chronic weight loss, swollen joints, shifting leg lameness, and muscle tenderness. Other clinical signs that have been infrequently reported include uveitis, hepatitis, abortion, and neurologic manifestations.

“The diagnosis of clinical disease can be challenging,” she explained, and that’s why there is such a need for a quick, reliable, in-house test for the infection. “We think there are many horses that are infected with the bacteria, but who are not showing any signs.”

Johnson said testing options in horses are limited. For humans, the offending tick or an associated rash is often found. However, horse owners less frequently see ticks on their horses, and it can be hard to see a rash on a dark-skinned, furry animal.

“The most common means of diagnosis include serology, and all the current equine tests require sample submission to equine reference labs,” she explained. “The tests that are currently available include an ELISA, IFA (immunofluorescent assay–both of these test for antibodies against B. burgdorferi), and a Western blot (a test for proteins associated with B. burgdorferi).”

These tests can take several days to complete and can lack specificity (the ability to identify negative cases; thus, they can present false positives), according to Johnson. She said the canine SNAP test could provide an inexpensive, fast means of diagnosis, which is critical when dealing with any type of disease.

“Results indicate that the test kits have high sensitivity and very high specificity for horses acutely infected with B. burgdorferi,” Johnson explained. “Validation of this test for horses provides practitioners with an inexpensive, in-house method to confirm infection.”

Get research and health news from the American Association of Equine Practitioners 2006 Convention in The Horse’s AAEP 2006 Wrap-Up sponsored by OCD Equine. Files are available as free PDF downloads