Leptospirosis is a zoonotic disease that affects a wide range of domestic and wild animals worldwide. The disease is caused by infection with the pathogenic bacterium, Leptospira
spp., primarily L. interrogans
in horses. Leptospiral infection is common in horses, however most are subclinical, resulting in little to no clinical signs.
Leptospirosis has been linked to equine recurrent uveitis
in the Southern United States. Investigations in the U.S. implicated leptospirosis in 3% of abortions in mares. Sporadic cases of leptospirosis have occurred in horses in Australia. The disease is not nationally notifiable.
spp. are thought to be spread to horses through wild animals (such as a raccoons, skunks, opossums, deer), and other livestock (cattle, swine). When animals are infected, they shed Leptospira
spp. organisms in their urine, contaminating the environment of where horses are kept. Higher incidences of leptospirosis have been documented to occur in animals kept with access to stagnant water such as ponds and/or low-lying swampy areas.
The incubation period is 2–20 days. Abortion or stillbirth usually occurs in pregnant mares from 6 months of gestation to term.