Entropion in dogs: an inward-turning eyelid

Overview

The abnormal position most commonly affects the lower eyelid. The upper eyelid, corner of the eye or just part of the eyelid margin can also turn inwards. Both eyes are often affected. Mild entropion may cause no outward symptoms.

The cornea is the clear surface layer at the front of the eye. A corneal ulcer is a break in the cell layer covering this surface. The significance of entropion depends on how much it irritates and damages this surface.

In UK veterinary patients in 2019, the recorded annual prevalence of entropion was 0.33%. An estimate based on patient records may miss some mild cases.

Causes

Conformational entropion is usually related to the shape of the head and eyelids. The length of the eyelid opening and the structure of the eye socket affect eyelid position. Uneven tension in the muscles that open and close the eyelids can contribute to inward rolling. Abnormal attachment or laxity of the supporting structures at the corner of the eye may also affect position.

Heavy facial skin folds can push an eyelid inwards. An excessively long, drooping eyelid can turn in, particularly at the outer corner. Entropion and an outward-turning eyelid, called ectropion, can occur in the same eye. The eyelid opening may then resemble a diamond.

In a short-muzzled dog, the tear duct opening in the lower eyelid can turn inwards with the lid. Tear drainage is disrupted and the eye waters more.

Spastic entropion develops when eye pain causes eyelid spasm. A corneal ulcer, for example, can trigger this spasm. Scarring after injury or inflammation can also pull the eyelid margin inwards. These acquired forms do not require an inherited eyelid defect.

Risk factors

Conformational entropion is often noticed in a young, rapidly growing dog. Diagnosis is usually made before one year of age. However, entropion caused by pain or scarring can develop at any age.

In UK patient records for 2019, annual prevalence was 15.41% in Shar Peis. The corresponding proportion in Chow Chows was 9.28%. In Neapolitan Mastiffs, it was 6.88%. These figures describe UK clinical records.

A short muzzle and heavy skin folds increase the risk of conformational eyelid problems. A long, narrow muzzle and deep eye sockets can also predispose to damage of the eye's surface. Inheritance is thought to involve several genes.

The type of hair touching the eye affects the severity of symptoms. Thick, stiff, short hairs damage the surface more than fine, thin hairs.

Typical symptoms

Signs of eye irritation you may notice at home include:

• Excessive tearing and constantly wet skin around the eye.

• Squinting and keeping the eye closed even when relaxed.

• Redness, particularly when entropion has damaged the cornea.

• Thick, mucoid discharge collecting at the edge of the eye.

• Brown pigment or blood vessels growing over the eye's surface with prolonged irritation.

A severely affected dog may seem subdued and clearly painful. Inward rolling at the inner corner, especially in a short-muzzled dog, may cause no visible signs of pain. Both keeping the eyelid closed and corneal cloudiness can interfere with vision.

Brown pigment may be concentrated towards the inner corner of the cornea.

Complications and consequences

Constant rubbing by hairs can inflame the conjunctiva and cornea. Prolonged irritation can cause corneal scarring. Scarring may leave some permanent visual impairment even after eyelid position is corrected.

Bacteria can multiply in a damaged cornea and worsen an ulcer. A deep ulcer can progress to perforation of the eye. Untreated severe damage can lead to loss of sight and eventually the eye itself.

The outlook for eyelid surgery is usually good. However, a good result may require more than one correction.

Diagnosis at the vet

Eyelid position and the eye's surface are assessed separately

Entropion is diagnosed during a clinical eye examination. The vet assesses inward rolling of the eyelid margin and hairs touching the eye's surface. Facial folds and any excessively large eyelid opening are checked at the same time.

Fluorescein staining helps detect breaks in the corneal surface. A Schirmer tear test measures tear production. Magnification and a slit lamp help assess ulcer depth. When examining a severe ulcer, cell or culture samples may be taken to select a suitable antimicrobial medicine.

A thorough eye examination may also include measuring pressure inside the eye. Temporary inward rolling caused by inflammation and pain is distinguished from a permanent conformational defect. Any underlying corneal or other eye disease is therefore investigated.

Hairs touching the eye without true inward rolling of the eyelid is called trichiasis. It is often found alongside entropion. Extra eyelashes growing from eyelid gland openings can also irritate the eye. Not every finding in a symptomatic eye therefore has the same eyelid abnormality as its cause.

Fine extra eyelashes can be difficult to detect without magnification and careful examination.

Treatment

Temporary protection for puppies and permanent correction

The vet assesses treatment needs according to the severity of inward rolling and damage to the eye's surface. Severe conformational entropion that damages the surface needs surgery. A young puppy's eyelid may initially be turned outwards with temporary tacking sutures. These usually stay in place for two to three weeks.

Tacking sutures may need to be replaced in a growing puppy. Head growth can change eyelid position. The timing of permanent correction is matched to head growth, which is sufficiently advanced in many dogs at around five to six months old.

In many dogs, definitive surgery is delayed until they approach adult size, at around six to 12 months. Some puppies can undergo permanent correction at four to five months. While waiting, temporary sutures can prevent hairs touching the eye's surface.

Tacking sutures can also be used in adult dogs with pain-induced spastic entropion. Once the original corneal inflammation has been treated, permanent eyelid surgery may not be needed.

Surgery is tailored to the eyelid problem

A common correction removes a crescent-shaped strip of skin beside the rolled-in eyelid. Closing the wound pulls the eyelid margin back towards its normal position. Excessively long eyelids may also need shortening and support at the outer corner. Heavy forehead folds may additionally require repositioning of facial skin.

Correction may be divided into a larger initial procedure and a smaller later one. This aims to reduce the risk of overcorrection and an outward-turning eyelid. Alongside eyelid correction, a corneal ulcer is treated according to its depth and any infection.

Veterinary-prescribed lubricants can protect the eye's surface. Any antimicrobial treatment addresses a secondary infection risk or confirmed infection. An ulcer that has lost at least 50% of the corneal stroma needs surgical assessment by a vet with ophthalmic expertise. Tissue from the conjunctiva, for example, can be grafted to support a severe ulcer.

Healing and the outcome of correction

Normal mild eyelid swelling after surgery usually subsides within 48 hours. Skin sutures are usually removed around ten days after eyelid surgery. A protective collar forms part of aftercare.

In complex outer-corner correction, 77 eyelid openings were operated on in 39 dogs. Four of the 77 eyes needed further surgery. Correction was considered successful in 94.8% of eyes. However, median follow-up was only 33 days, ranging from five to 1,077 days.

Success meant satisfactory eyelid position without a need for further surgery. Short and variable follow-up does not establish every dog's long-term outcome.

Of these operated eyelid openings, 57, or 74%, healed without recorded complications. Minor complications occurred in 11, or 14%. Major complications occurred in nine, or 12%. These results concerned complex diamond-eye correction, rather than the prognosis for all entropion surgery.

Minor complications included wound infections and delayed healing. Major problems included failure of the fixation and wound breakdown. One dog was euthanased because of severe self-injury and difficulties providing care at home.

Prevention

Preventing conformational defects involves avoiding extreme head and eyelid shapes that interfere with eye function. Breeding choices aim to reduce eye diseases that cause pain, impaired vision and a need for surgery. Some official eye screening schemes record eyelid defects even when a dog has no symptoms.

Some breeding guidance recommends choosing a mate as free as possible from this condition for a mildly affected breeding dog. Under this guidance, severely affected dogs needing surgery or with impaired vision should not be bred. Breed-specific screening programmes may set additional eye examination requirements.

Some official eye screening schemes have no general minimum age for examination. However, certain breed programmes require the dog to be at least 12 months old.

Important for dog owners

Eyelid position is monitored in a growing puppy during temporary treatment. Tacking sutures do not always remove the need for later permanent correction. After successful correction, most dogs can live without ongoing eye pain.

A protective collar prevents scratching and rubbing of the operated area. After the complex eyelid-corner surgery, collars were used for at least 14 days. Vigorous scratching can open the wound or damage the surgical fixation.

Contact the treating practice if pain increases, the eye becomes cloudy or the wound opens. Follow your dog's collar and follow-up instructions. Record previous eye symptoms, injuries and procedures so they are known at later visits and when breeding health is assessed.

A wound infection may cause redness and pus. Follow-up visits check that the cornea is healing appropriately. Under some official eye screening schemes, a review panel does not overturn a diagnosis simply because treatment has removed the symptoms.

Frequently asked questions

Can a puppy grow out of entropion?

In some puppies, eyelid position improves as the head grows. Temporary tacking sutures can keep hairs away from the eye's surface during growth. They may need replacing before permanent correction. A severe abnormal position damaging the cornea needs surgical treatment.

Does every case of entropion need surgery?

Mild, symptom-free inward rolling does not always need a procedure. Persistent or recurrent conformational entropion may require corrective surgery. Pain-induced spastic entropion may improve when the original eye disease is treated. Damage to the eye's surface affects treatment urgency.

Is entropion the same as extra eyelashes?

In entropion, the eyelid margin turns inwards. In distichiasis, extra eyelashes grow from eyelid gland openings. Both can irritate the eye's surface and damage the cornea. Treatment depends on the hair or eyelid problem identified. Entropion can also occur alongside ordinary skin hairs touching the eye, called trichiasis.

Will vision return after eyelid surgery?

Correcting eyelid position can reduce ongoing irritation of the eye's surface. However, corneal scarring from prolonged rubbing can leave permanent visual impairment. Both eyelid position and corneal condition are therefore assessed before deciding on treatment.

Can a dog be bred after surgery?

Some breeding guidance advises against breeding dogs needing surgery for severe entropion. Surgery does not remove the concern about an inherited basis for the disease. Breed-specific eye screening requirements should also be checked separately. Some official eye screening schemes record eyelid defects even without visible symptoms.