The uvea is the area of the ocular globe that encompasses the iris, the ciliary body and the choroid. When it is inflamed it is called uveitis, this condition is relatively common in the horse. The clinical signs of a uveitis crisis are those of ocular pain (blepharospasm, photophobia, conjunctivitis, ocular discharge and myosis). Some infectious diseases like Lyme disease or leptospirosis can be the origin of uveitis in horses.
Subsequent complications can be severe as they are the main cause of acquired loss of vision in the horse. Recurrent isolated uveitis is a vice, it is therefore checked for during a pre-purchase examination.