At a panel discussion held Oct. 8 in Lexington, Kentucky, Zoetis introduced its new Lepto EQ Innovator vaccine against equine leptospirosis, which can cause abortion in pregnant mares, kidney and liver failure, and equine recurrent uveitis (ERU, the most common cause of blindness in horses). This is the first USDA-approved, equine-specific vaccine labeled to help prevent leptospirosis caused by Leptospira pomona.

Horses become infected with Leptospira bacteria when it enters the body via mucous membranes or wounds. Carrier hosts, such as rodents, wildlife, and domestic animals, spread the bacteria in their urine, which horses can come in contact with when it contaminates water or soil. Infected horses also shed the bacteria in their urine, which can lead to leptospirosis outbreaks on farms. The disease is zoonotic, meaning it’s transmissible to humans.

The development of a vaccine against the serovar Leptospira pomona (which is the serovar most frequently associated with clinical disease in horses in North America) is significant because leptospirosis causes serious and costly health problems in horses. Economic losses from horses with leptospirosis-associated ERU or abortion amount to hundreds of millions of dollars, according to the University of Kentucky Veterinary Diagnostic Laboratory and Poulsen Nautrup et al.

In Zoetis’ efficacy studies, leptospires were detected in 0% of vaccinated horses after being challenged with L. pomona. The company’s safety studies showed the Lepto EQ Innovator vaccine to be 99.8% reaction-free among vaccinated horses