Lepto 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 the past two years there were less than 10 each year. Through Jan. 29 of this year, there have been 33 cases, according to Neil Williams, DVM, PhD, of the University of Kentucky's Livestock Disease Diagnostic Center. This includes cases from fall and winter 2003 that would have been included in this foaling season (these will be counted as 2004 foaling season losses).

Signs of leptospirosis include mild depression, loss of appetite, and a fever of 103-105ºF 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.

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 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.

It's crucial to isolate any mares which have aborted and thoroughly disinfect their stalls and any equipment that has come in contact with them. Horses have been documented to shed lepto for 110 days after infection.

There are no commercially available lepto vaccines for horses; those used against lepto 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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