Introduction
Entropion is the inversion, inward rotation (toward the eye), of all or part of the margin of an upper or lower eyelid, or both. It causes the hair-bearing part of the eyelid to rub against the conjunctival and corneal surfaces, leading to irritation and spasms of the muscles around the eye. Entropian can be congenital or acquired. The clinical signs in dogs vary depending upon the cause of the condition but generally range from redness and ocular discharge to severe corneal damage.
Symptoms of Entropion in Dogs
Entropion can be congenital or acquired. It is common in dogs and usually is apparent before one year of age - especially if it is congenital/developmental. There is no gender predisposition to this disorder. However, there is a definite genetic predisposition in certain breeds, although the mode of inheritance is not completely understood. Affected breeds include Chow Chows, Shar-peis, Norwegian Elkhounds, Boxers, Rottweilers, Cavalier King Charles Spaniels, Maltese, Sporting dog breeds (pointers, retrievers, spaniels), brachycephalic breeds (English bulldogs, Pugs, Pekingese), toy dog breeds (miniature and toy poodles, Yorkshire terriers) and certain large dog breeds (Mastiffs, St. Bernards, Newfoundlands).
While most cases of entropion are developmental due to a genetic predisposition tied to facial conformation and muscular and ligamentous eyelid support, entropion can also be acquired by dogs of any breed. Acquired entropion can be caused by eyelid trauma, chronic infection, obesity, marked weight loss or loss of facial muscle tone around the eyes due to old age and the accompanying increased laxity (looseness) of the skin. Acquired entropion can be seen at any age but tends to be more common in older dogs.
Clinical signs of entropion range from mild to severe. In mild cases, owners may only notice tearing and redness. They may see twitching of the eyelids and muscles around the eye (called blepharospasm). In more pronounced cases, owners will see the visible inrolling of the upper and/or lower eyelids. The skin around the eyes may appear thick and heavy. The eyes may seem swollen, and the ocular discharge can become thick and “gummy,” containing pus or even blood. The dog may have difficulty opening its eyes (especially in sunlight) and may appear depressed or even aggressive due to the pain this condition can cause.
In severe cases of entropian, the dog will be in constant pain. The cornea can ulcerate and potentially rupture. Self-trauma in an effort to relieve the pain can contribute to deterioration of the dog’s condition.
Signs of entropion usually – but not always - occur in both eyes. If the cause is genetic, clinical signs will be apparent early in life and can be seen even in puppies that are only a few weeks old. In fact, novice breeders of affected breeds (especially Chows and Shar-peis) may think that their puppies’ eyes have not opened by 4 or even 5 weeks of age, when in reality the puppies have severe congenital entropion.
Entropion is extremely painful. Severe developmental entropion will not improve without treatment, and the symptoms will worsen with time. If left untreated, entropion can lead to corneal scarring, ulceration, rupture and eventually blindness.