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. It 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.


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?

I t 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.


Where to find more information?

Gelatt, K.N. 1991. Veterinary Ophthalmology. Lea and Febiger.

Copyright © 1998 Canine Inherited Disorders Database. All rights reserved.
Revised: August 18, 2003.