Increase In Leptospirosis Reported In Kentucky

Leptospirosis, often called just "lepto," can cause flu-like illness in horses that sometimes results in abortion or uveitis (moon blindness). In Kentucky, there seems to be a cyclic pattern to abortions caused by leptospirosis. In 2001, there were about 40 cases, but over the past two years there were less than 10 each year. Through Jan. 12 of 2004, there have been already 27 cases, according to Neil Williams, DVM, PhD, of the University of Kentucky's Livestock Disease Diagnostic Center.

Signs of leptospirosis include mild depression, loss of appetite, and a fever of 103-105° that lasts two to three days. Abortion can occur several weeks after the fever in pregnant mares (usually during the second half of gestation), and uveitis can strike months later.

Bacteria that cause leptospirosis are different from other bacteria in that they are spiral shaped and are motile. Necropsy might reveal lesions scattered randomly over the placenta, leading to placentitis. Occasionally foals are born alive and can be saved with aggressive antibiotic therapy, but they are generally weak and don't live.

Leptospira bacteria are spread through urine (infected animals can shed the micro-organism for months after exposure) and placental fluids, and indirectly through contaminated feed and water. Leptospira can also be transmitted to horses from cattle and wild ruminants such as deer and elk. Wet environmental conditions seem to increase the risk.

There's little you can do to detect leptospirosis ahead of time; a rising lepto titer in the blood is diagnostic, but blood samples must be taken on a frequent basis to detect it. If you do happen to identify a pregnant mare with the disease, treating the mare with antibiotics might be successful in preventing abortion and will reduce shedding in sick mares and mares following abortion. It's crucial to isolate any mares which have aborted and thoroughly disinfect their stalls and any equipment that have come in contact with them. Horses have been documented as shedding lepto for 110 days after infection.

There are no commercially available lepto vaccines for horses; those used against leptospirosis in cattle are not approved for use in horses.

About the Author

Kimberly S. Brown

Kimberly S. Brown was the Publisher/Editor of The Horse: Your Guide To Equine Health Care from June 2008 to March 2010, and she served in various positions at Blood-Horse Publications since 1980.

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