What Causes Recurrent Uveitis in Horses?
Any injury to a horse’s eye may result in the development of uveitis and subsequent ERU. The two most common causes of ocular injury are trauma and infectious diseases. Trauma to the eye may result from a blunt blow or by penetration of the globe (eyeball) by a sharp object. Other common causes include: • Bacterial organisms (Leptospira, Brucella, Streptococcus) • Viral agents (equine influenza, equine viral arteritis, parainfluenza type 3) • Parasites (Onchocerca, Strongylus, Toxoplasma) • Miscellaneous (endotoxemia, tooth root abscesses, neoplasia) Regardless of the inciting cause, it is believed that the ERU is immune-mediated. This means that once the primary infection resolves, subsequent episodes of eye inflammation are the result of overaction of the horse’s own immune system in response to active immune cells such as T-lymphocytes.
