Entropion is inversion or ‘rolling in’ of the eyelids, leading to contact between eyelid hairs and the cornea. This contact is irritating and uncomfortable, and causes corneal ulceration, scarring, and pain.
The cause of entropion may be either primary or secondary. Primary causes are inherited and include excessive eyelid length, skull conformation, anatomy of the orbit, weak eyelid cartilage, or extensive facial folds. Primary entropion is common in certain dog breeds including the Chow Chow, Shar Pei, Bouvier des Flandres, Rottweiler, Labrador, Golden Retriever, Great Dane, St. Bernard, Leonberger, Bloodhound, English Cocker Spaniel, Basset Hound, Pekingese, Shih Tzu, Pug, Toy and Miniature Poodle, Cavalier King Charles Spaniel, and English Bulldog; and in Persian and Maine Coone cats.
Secondary entropion may be caused by corneal ulcers or other source of severe pain, or loss of eyelid support (e.g. sunken eye, muscle atrophy, etc) and can occur in any breed. Signs of entropion include squinting, tearing, ocular discharge, swelling, and redness. Corneal changes may be present as well, such as ulceration, cloudiness, or pigmentation. Severe cases can affect vision as well. Contact between eyelid hairs and the cornea is painful and leads to more squinting and globe retraction, which makes the entropion worse. This vicious circle often requires surgery before resolution is possible.
Treatment of entropion depends on the cause and the age of the animal. In mild cases without active corneal disease, a lubricating ointment can help protect the cornea. In young animals, tacking sutures or staples are placed to temporarily hold the eyelid everted while the animal grows, usually remaining in place for up to 4-6 weeks. This type of entropion will not often need additional treatment. Temporary tacking is also useful to ease the pain associated with spastic (secondary) entropion in adult dogs. Severe or recurrent entropion should be treated surgically. Surgery involves permanently rolling out the eyelid and/or shortening the eyelid length. Complications following surgery can include recurrence of entropion, corneal ulceration, suture dehiscence, or infection.