Entropion is a condition in which the eyelids roll inwards allowing the surrounding hair to contact the surface of the eye and irritate the cornea. It can affect upper and/or lower eyelids and can be one or both eyes. Entropion can result in corneal ulceration if not treated. It can be genetic or secondary to another issue.
Breed specific issues are the most common form of entropion. Short nose (brachycephalic) breeds such as Pugs or Boxers are predisposed due to the shape of their heads leading to excessive tension on the ligaments around the inner eye. This tension causes upper and lower eyelids to roll inwards. This is exacerbated by excess skin folds and prominent eyes.
Giant breeds such as Great Danes and St. Bernards often suffer from entropion at the outer corners of the eyes due to slack ligaments in this area. A similar defect can be seen in some of the sporting breeds such as Labradors and Irish Setters. Entropion is most commonly seen in Shar Pei due to the excessive skin folds that the breed has been selectively bred for. Most of these cases of genetic entropion will be present from a young age.
Secondary causes include eyelid trauma, nerve damage, weight loss and aging. If a dog loses weight, it also loses the fat pad behind the eye; this causes the eyeball to sink backwards resulting in a tendency for the eyelids to roll inwards. Aging leads to a loss of collagen so the skin becomes slacker, in dogs with skin folds around the eyes this can lead to entropion.
Symptoms of entropion include increased ocular discharge, constant irritation, blood shot eyes, blinking and squinting. If entropion is severe or chronic then the constant contact of hair on the cornea can lead to pigmentation or ulceration so the eye appears dark or cloudy.
Diagnosis of entropion is made by the vet on close examination. They will check for corneal ulceration by staining the eye with fluorescein, this sticks to any damaged parts of the cornea. If an ulcer is present, then this will require aggressive treatment to prevent severe or permanent damage to the eye.
In most cases of primary entropion surgical correction is required. In young dogs, surgery should be delayed until the skull has matured from around 6 months old. In severe cases in puppies their eyelids can be temporarily tacked from 2 weeks old. This procedure is very common in Shar Pei puppies. Older dogs undergo an operation called blepharoplasty where excess skin is taken from affected eyelids so tightening them. Both eyes can be operated on at the same time and both upper and lower eyelids if required. Prognosis following surgery is excellent although recurrent surgeries maybe required.
In secondary cases just correcting the primary problem may resolve the entropion.