Entropion has been documented in most dog breeds, although there are some breeds (particularly purebreds) that are more commonly affected than others. These include the Akita, Pug, Chow Chow, Shar Pei, St. Bernard, Cocker Spaniel, Boxer, Springer Spaniel, Labrador Retriever, Cavalier King Charles Spaniel, Neapolitan Mastiff, Bull Mastiff, Great Dane, Irish Setter, Rottweiler, Poodle and particularly Bloodhound. The condition is usually present by six months of age. Entropion can also occur secondary to pain in the eye, scarring of the eyelid, or nerve damage. The upper or lower eyelid can be involved, and one or both eyes may be affected. When entropion occurs in both eyes, this is known as "bilateral entropion."
Upper lid entropion involves the eyelashes rubbing on the eye, but the lower lid usually has no eyelashes, so hair rubs on the eye. Surgical correction is used in more severe cases. A strip of skin and orbicularis oculi muscle are removed parallel to the affected portion of the lid and then the skin is sutured. Shar Peis, who often are affected as young as two or three weeks old, respond well to temporary eyelid tacking. The entropion is often corrected after three to four weeks, and the sutures are removed.