About Leptospirosis in horses

Article- October 2016 RBE Newsletter Leptospirosis: What is it and will the new vaccine protect my horse? Jennifer Allen, DVM As we rapidly approach autumn and say goodbye to summer, it's a good time to prepare our four legged friends for routine fall vaccines and wellness exams. There is a new (2015) vaccine on the market that you may have heard of called Lepto EQ Innovator, produced by Zoetis. The vaccine was developed to aid in the prevention of Leptospirosis in the horse. So what exactly is leptospirosis? Leptospirosis is a zoonotic (can be transferred between animals and humans) spirochete bacterium that is distributed across the world, but is concentrated in areas with higher rainfall. In the horse it is mainly known for causing recurrent uveitis (moon blindness), abortion, renal failure, and occasionally systemic disease. The bacterium is transmitted to the horse from standing water, soil, bedding, feed or drinking water that is contaminated with urine shed from an animal that is a carrier or host for the leptospira organism. Leptospira live in various host mammals including skunks, raccoons, white tailed dear, and opossums, all of which can shed the bacteria via urine. All of these mammals live in the PNW and are often in shared environments with our horses. The horse contracts the bacterium through mucous membranes or pre-existing wounds. The bacterium then congregates and persists in the eyes, kidneys, and in the female reproductive tract, supporting the pathological presentations of uveitis, nephritis and abortion in the horse. If you have foaling mares it's a good idea to discuss the inclusion of this vaccine in their wellness protocol with your veterinarian. EQUINE RECURRENT UVEITIS (ERU) has been a persistent issue in horses and we have seen multiple cases of it lately. It is the most common cause of impaired vision and blindness in horses and leptospirosis is one of the initiating factors for ERU. If left untreated or caught too late ERU, can lead to catastrophic eye pathologies including glaucoma. We submit a blood sample from horses with ERU to be tested for leptospirosis because it will influence our treatment plans and because roughly 70% of all ERU cases are associated with leptospirosis. The Lepto EQ Innovator vaccine has been shown to be safe and effective. Zoetis states that the vaccine prevents colonization of the bacteria in the kidneys, leading to a decrease in urinary shedding of bacteria by the horse, which can decrease horse to horse transmission of the disease. The vaccine has also been shown to provide a safe immune response and in a study where vaccinated horses were challenged with L. pomona, they showed 0% bacterial shedding in the urine. Pharmaceutical companies have already created leptospirosis vaccines for dogs, cats, and livestock that have been on the market for a number of years. The vaccines have proven to be very beneficial for keeping our pets healthy and happy. They have also helped keep production sound and economical in the livestock industry. Although the Zoetis equine vaccine has only been on the market for a year, it has been shown to be effective in protecting our horses and is well worth considering in the vaccination protocol for your horse. We are now stocking Lepto EQ Innovator and we are happy to discuss its use for your particular horse and management conditions. Whenever you see Dr. Bo, Dr. Crystal, or myself at your barn please feel free to ask us about it and we would be happy to answer any questions! Until then, happy trails and continue to enjoy the beautiful weather while it lasts!