Equine recurrent uveitis: A clinical manifestation of leptospirosis

Summary Leptospirosis is a zoonosis of worldwide distribution affecting domestic animals, wildlife and man. The bacterial disease is caused by pathogenic Leptospira spp., which are transmitted from reservoir hosts to accidental hosts. Horses are accidental hosts and can become susceptible to leptospiral infections. Widespread exposure to leptospires exists and is significantly more common than clinical disease. Leptospirosis can have different clinical manifestations including abortion, still birth, systemic disease with hepatic or renal dysfunction, and equine recurrent uveitis (ERU). ERU is the most frequently encountered clinical manifestation and this article will focus on the review of leptospira‐associated ERU. Equine recurrent uveitis is the most common cause of vision impairment and blindness in horses. The pathogenesis of leptospira‐associated ERU involves direct bacterial effects and immune‐mediated responses. Clinical signs vary between the acute and chronic phases of the disease and progress over time. The diagnosis of leptospira‐associated ERU can be difficult and usually requires a combination of diagnostic tests. Medical and surgical treatments have been described with varying outcomes. The prognosis for sight is usually poor, although core vitrectomy may improve the outcome. Avoidance of leptospiral exposure of horses is the only reliable prevention of leptospira‐associated disease.