chloelogoa

Eversion or Inversion of the Nictating Membrane

third eyelid protrusion syndrome, cherry eye, follicular ophthalmitis, proplapse of the nictating membrane,
 talalogoa

While not the most visually appealing condition (for the owners or the afflicted dog), cherry eye is actually a fairly common and benign occurrence in many breeds of dogs.  Though it may appear somewhat like a tumour or even an awfully big bug bite, the ‘cherry’ on your dog’s eye is usually the third eyelid and an associated prolapsed (or popped out) lymph node. Normally they are hidden neatly in the corner of the eye, but as a result of poor conformation, inflamation or trauma, the third eyelid may flip out of place.  Sometimes the resulting "cherry" can be gently pushed back intop place, but surgery may be needed if the eye becomes painful.

The third eyelid or nictating membrane (also called membrana nictitans or haw) is a protective triangular shaped structure at the inner corner of each eye, next to the nose that sometimes covers part of the eye. It consists of a t-shaped cartilage and a tear gland.  When needed the third eyelid can sweep across the eyeball, like a windshield wiper, to help remove debris, add extra protection and moisture.

It is unclear what causes cherry eye, but research shows that it may be related to the connective tissue that regularly holds the gland in place and connects it to surrounding structures. When this tissue is particularly weak, prolapse is more likely.  A proplapse of the gland occurs when the base of the gland flips up and is seen above and beyond the border of the third eyelid. This means that the third eyelid is rolled outwards because of a curvature of the cartilage. The proplapsed glands becomes swollen and inflamed.  The disease is seen in both eyes and is common in large breed dogs.
It is important to correct cherry eye in dogs, as the exposed gland is at a high risk of injury and infection. Also, the mucous discharge that sometimes accompanies the swollen gland can be very irritating; if the dog decides to rub or scratch at it, the entire eye is at risk of injury.

Treatment for cherry eye does require surgery, however, the procedure is relatively straightforward and routine. Under general anaesthetic, the nictitans gland is replaced to its normal position and re-attached to the deeper structures of the eye.

Previously, it was routine to simply remove the gland, but this method has been shown to cause many problems for the dog later in life. Without the tear-producing function of this gland, dogs are prone to developing a disease called keratoconjunctivitis sicca (or more simply put, dry eye). This dryness can still to occur in those dogs who have their gland surgically repositioned, however, the incidence is much lower (it occurs in approximately 20% of cases).

With today’s veterinary expertise, there are few complications related to replacing the gland. Dogs should be able to go home on the same or next day, often on a course of antibiotics to prevent infection. In some cases, however, the results of this surgery are not as permanent as owners would like. Dogs with cherry eye can develop the problem again, and may require the repositioning surgery two or three times in their lives. Success rates are greatest, and recurrence is the least likely when the surgery is performed shortly after the prolapse.

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ciddlogoa

Eversion or Inversion of Third Eyelid Cartilage


http://www.upei.ca/cidd

related terms: cherry eye, eversion or inversion of third eyelid cartilage, prolapse of nictitating membrane

What is the third eyelid?

The third eyelid is a triangular shaped structure in the inner corners of your dog's eyes that you may notice sometimes partly covers the eye. Itnictit1 consists of a t-shaped cartilage to provide support, and a tear gland. The third eyelid is important in protection of the surface of the eye, and in tear production. It is also called the nictitating membrane (or membrana nictitans) and haw.

Abnormalities:
A prolapse of the gland or "cherry eye" occurs when the base of the gland (embedded in the cartilage) flips up and is seen above and behind the border of the third eyelid. The prolapsed gland becomes swollen and inflamed. The condition frequently occurs in both eyes and is most common in young dogs of the breeds listed below.

Eversion of the cartilage appears as a scroll-like curling of the cartilage, usually in an outward direction, although inward curling also occurs (inversion of the cartilage). It is most common in young large breed dogs.

Another condition of the third eyelid is atypical pannus. This occurs in German shepherds.

How are abnormalities of the third eyelid inherited?
It has not been proven that this condition is inherited, but dogs of the breeds listed below are predisposed.

What breeds are affected by abnormalities of the third eyelid?

prolapsed gland of the third eyelid: Basset hound, beagle, bloodhound, Boston terrier, boxer, English bulldog, Shar pei, cocker spaniel, Lhasa apso, Newfoundland, Shih tzu, Saint Bernard

eversion of the cartilage of the third eyelid:  German short-haired pointer, Irish setter, Newfoundland, Saint  Bernard, and Weimaraner

For many breeds and many disorders, the studies to determine the mode of inheritance or the frequency in the breed have not been carried out, or are inconclusive. We have listed breeds for which there is a consensus among those investigating in this field and among veterinary practitioners, that the condition is significant in this breed.

What do abnormalities of the third eyelid mean to your dog & you?

Both conditions cause chronic irritation of the conjunctiva and cornea, and if untreated, can lead to keratoconjunctivitis sicca.

How are these conditions diagnosed?
Both conditions generally occur in younger dogs and are readily diagnosed from the appearance of the eye. In  cherry eye, the glandular tissue protruding behind the third eyelid may be markedly swollen and inflamed.  It must be distinguished from a tumour of the third eyelid, which is rare.

How are these conditions treated?
prolapsed gland: The gland and cartilage are anchored surgically in the proper position. Sometimes the prolapse recurs. The gland itself must not be removed, as inadequate tear production will result causing keratoconjunctivitis sicca.

eversion of cartilage: The abnormal folded cartilage is removed surgically.

Breeding advice
It is preferable not to breed dogs that have developed these conditions.

FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.

Where to find more information?
Gelatt, K.N. 1991. Veterinary Ophthalmology. Lea and Febiger.

Copyright © 1998 Canine Inherited Disorders Database. All rights reserved.

Permission to reprint is granted  by
Alice Crook, DVM Coordinator, Sir James Dunn Animal Welfare Centre
Atlantic Veterinary College University of Prince Edward Island

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Cherry Eye
Cherry Eye in Dogs
 Cherry Eye in Dogs


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