Problems affecting the eyelids may be congenital (present at birth) or may occur as a result of injury, infection, or exposure to various types of irritants.
Entropion is the turning in of the edges of the eyelid so that the eyelashes rub against the eye surface. It occurs in foals as a congenital defect. It may also be acquired in older horses as a result of chronic eye irritation or spasms. The turning in of eyelashes or facial hairs causes discomfort and irritation of the conjunctiva and cornea. Extremely long lashes can cause scarring, abnormal coloring, and possibly the formation of slow-healing sores or ulcers on the cornea.
Early spasms of entropion may be reversed if the cause is removed or if pain is lessened. Turning the lid hairs back away from the eye with stitches in the lid, injections of medication into the lid close to the area where the lid is turning in, or using anesthetics to block the nerves in the eyelids are some of the methods that have been used to lessen the pain. Established entropion may require surgery to correct the defect.
Lacerations of the Eyelid
Eyelid lacerations (rips or tears in the eyelid) are common in horses. They must be repaired quickly to avoid infection, reduce swelling, and prevent further damage to the eye. In many cases, your veterinarian will clean the wound and use stitches to repair it so that minimal scarring occurs.
Inflammation of the Eyelids (Blepharitis)
Inflammation of the eyelids can result from the spreading of a generalized inflammation of the skin (dermatitis), conjunctivitis (inflammation of the conjunctiva), local glandular infections, or irritants such as plant oils or sunlight. Infection with certain fungi or bacteria can also lead to inflammation of the eyelids; however, this is uncommon in horses.
Parasites, such as eyeworms (see Eye Disorders of Horses: Eyeworm Disease (Thelaziasis) in Horses) and the larvae of stomach worms (Habronema species), are a common cause of blepharitis in horses, particularly during warm-weather months. Treatment is targeted toward removing the parasites by the use of appropriate antiparasitic drugs, although eyeworms can sometimes be removed directly from the surface of the conjunctiva using forceps. If needed, topical ointments to reduce swelling may be prescribed.
Last full review/revision July 2011 by Kirk N. Gelatt, VMD, DACVO; Steven R. Hollingsworth, DVM, DACVO; David G. Baker, DVM, MS, PhD, DACLAM