Don’t overlook this “bug” that can cause abortion and uveitis (moon blindness).

Many horse people don’t know that much about leptospirosis. If you have heard of it, it is probably in reference to cattle, other livestock, or maybe dogs. However, leptospirosis does affect horses, and it can be the cause of some serious health problems, including abortion in pregnant mares and chronic uveitis (moon blindness). It is a disease that has not been studied much in the horse, but several scientists have been calling for further research and for the development of an effective equine vaccine.

What is it?

Leptospirosis is a zoonotic (transmitted between animals and man) bacterial disease found worldwide that can affect any mammalian species, including humans, wildlife, rodents, livestock, and, yes, horses. The disease is caused by leptospires, which are motile (capable of moving) bacteria called spirochetes. Leptospires are subdivided into serovars and serogroups (subgroups). Those of importance to the horse include pomona, grippotyphosa, hardjo, bratislava, canicola, and icterohaemorrhagiae. They are very common in both domestic and wild animals.

Craig Carter, DVM, PhD, director of the University of Kentucky’s Livestock Disease Diagnostic Center (LDDC) and professor of epidemiology, College of Agriculture, tells us horses become infected through mucous membranes of the eyes or mouth and sometimes through broken skin by contact with infected urine, blood, or tissues. Horses can become infected by eating hay or grain that has been contaminated by infected urine, or they can contract it by drinking from standing water that has been similarly affected. In some cases horses are affected by the direct splashing of infected animals’ urine into the eyes or mouth.