Entropion

an inward rotation of the eyelid margin such that the haired skin contacts the conjunctival and corneal surfaces of the eye

What is it?
Entropion is usually an inherited condition where the eyelids are misshapen and turn inward to rub on the cornea.   The degree of irritation or pain caused to the animal depends on the patient, type of entropion, severity, and duration of the disease.

What causes it?
Entropion may be primarily due to a developmental defect, or secondarily from another ocular or systemic disease.  A combination of primary and secondary entropion is not unusual.

What breeds are susceptible to it?
Primary entropion is often breed associated, commonly seen in the Chow Chow, Shar-Pei, Rottweiler, Labrador Retriever, Cocker Spaniel, Bloodhound and many others.  Primary entropion is generally considered inherited as a simple dominant trait in some breeds but in others the mode of inheritance is undetermined.  Primary entropion may be simple or complicated depending on the predisposing anatomy and how severely affected the patient.  Secondary entropion may be associated with pain due to intraocular disease, skin disease, trauma, and many other conditions that affect the animal’s general health.  All entropion should be considered significant.

Frequent Breed Dispositions:

-  Gun Dog Breeds  lateral aspect of lower eyelid is most commonly involved

-  Large or Giant Breeds lateral canthus is usually involved

-  Shar Peis can have a 360º entropion which can present as early as 15 days of age

-  Toy and miniature Poodles most commonly have a medial lower eyelid entropion

-  Chow Chow, Bull Terrier, Rough and Smooth Collies and Shetland Sheepdogs have an entropion associated with micropalpebral fissure

-  In breeds like St. Bernard, Bloodhound, Newfoundland, Clumber Spaniel and Neopolitan Mastiff, Euryblepharon, excess horizontal eyelid length, allows both entropion and concurent ectropion to occur

How is it diagnosed?
The first consideration is the overall health of the animal.  Primary entropion is generally seen in young animals so systemic abnormalities other than skin disease are generally not a consideration.  A careful evaluation of the patient must be performed when secondary entropion is diagnosed.  A diagnostic evaluation of a patient affected with secondary entropion may include testing for Cushing’s disease, hypothyroidism, Demodectic mange, inhalant and food allergies, intraocular disease, and immune-mediated disease.  If the cause of secondary entropion is corrected early in the course of the disease, surgery may be avoided.

How is it treated?
Entropion often requires surgical correction.  The surgical procedure chosen depends on the patient’s age, breed, and severity of disease.  In young animals a simple tack suture can be used to roll the eyelid margin away from the eye.  If the eye irritation can be relieved as the animal ages the head may enlarge to correct the disease.  Older patients require more extensive surgical intervention requiring removal of some eyelid tissue.  The earlier the condition is addressed the less extensive surgery is needed.  Correcting entropion is really more of an art than a science.  There is no way to exactly measure how much tissue should be removed. Hence, it is better to under-correct than to take too much tissue.  It is much easier to return to surgery and remove a little more tissue than it is to put tissue back after it has been removed.

What is the prognosis?
Unfortunately entropions can recur, especially in secondary cases where it is difficult to correct the initiating problem.  Males may need to be neutered to prevent the effects of testosterone on the eyelid muscles. (Testosterone is the hormone that enables males to develop strong muscles.  If muscles are too strong they collapse the eyelid inward, recreating the entropion).  If under correction is initially performed a second and rarely a third surgery may be needed to perfect the eyelid margin but additional surgeries are not as extensive or expensive as the initial surgery.