Leptospirosis – The Disease in Horses

You vaccinate your dog every year for this deadly disease. Did you know that horses can get "Lepto" too?


Leptospirosis is a bacterial disease found in many animals. It is zoonotic, which means it can also be spread to humans. Horses become infected when mucus membranes (in their eyes, mouth, and nose) or cuts and scratches on the legs contact infected urine or blood. Horses can also become infected by ingesting hay or grain and water that has been contaminated by infected urine.


Clinical signs include depression, fever, loss of appetite, and signs of uveitis -- also called moon blindness -- where inflammation within the eye causes tearing, swelling, discharge, and cloudiness. Chronic uveitis can lead to blindness. Pregnant mares can also abort. Kidney and liver failure can occur with severe infections, leading to death.

It is unclear how many horses are affected by this disease, some estimates suggest 45% of horses have been or will be exposed.


How can you prevent this disease? Good farm management is important. Keep feed sources protected from wildlife (such as mice, rats, possums, raccoons, deer, etc.). Refresh standing water in troughs.


Vaccination is a new option. In 2015, Zoetis released an equine Leptospirosis vaccine. This vaccine is considered safe in horses 6 months and older, and is safe and recommended for mares during pregnancy to prevent leptospirosis-induced abortion. Studies suggest it is effective in preventing the infection, but because it is a new vaccine, the data is limited to date.