My Horse Has Excessive Tearing. Could It Have Equine Recurrent Uveitis?
What is equine recurrent uveitis? Equine recurrent uveitis (ERU), also known as moon blindness or periodic ophthalmia, is the leading cause of blindness in horses worldwide. Equine recurrent uveitis is inflammation inside the eye that recurs at regular
intervals over the life of a horse. It first affects the uvea, which contains the vascular components of the eye and is essential for proper nutrition and function of the eye. The inflammation can affect other parts of the eye and lead to cataracts, glaucoma, retinal detachment, and other blinding damage. The underlying cause for ERU is controversial and is still debated; however, there is a strong immune mediated (autoimmune) component to the disease, in which the body’s own immune system attacks the tissues of the eye. What are clinical signs of ERU that a horse owner may notice? The more common early signs of ERU noticed by owners include tearing, swelling of the eyelids, squinting,
cloudiness, and/or visual impairment. ERU can affect one or both eyes. Appaloosas, European warm bloods, and draft breeds are over represented, but any horse breed can be affected with ERU. How is ERU diagnosed? ERU can be diagnosed by a complete ophthalmic examination by a veterinary ophthalmologist. In the early stages of ERU, there are only subtle changes that only an experienced eye will find and diagnose. What is the treatment for ERU? Treatment typically includes topical and oral anti-inflammatory medications. Another option offered at The Animal Eye Institute is surgically placed cyclosporine implants. These implants are placed between layers of the eye and slowly release medication, which is an immunomodulatory and anti-inflammatory drug. The goal for the implants is to reduce the amount medication needed and to minimize the number of ERU flare-ups.
What is the prognosis for ERU? The long-term prognosis for ERU is guarded. Some horses respond well to medical management; however, others develop secondary complications that lead to discomfort and permanent blindness. These complications include cataracts, glaucoma, shrinkage of the eye, and retinal damage, all of which lead to blindness and are difficult to treat. Horses diagnosed with ERU require diligent lifelong care by horse owners and their veterinary ophthalmologist.