Many of us at one time or another have seen a dog with a red, swollen bulge in the corner of his eye and thought “ouch!” This rather unsightly, painful-looking condition is called prolapsed nictitating membrane, also referred to as “Cherry Eye”.
Most animals, including dogs and cats, have a third eyelid (called the nictitating membrane) to help protect their eyes. This translucent membrane is usually not visible when an animal is awake and alert, but may be seen coming up from the inner corner of the eye when the animal is sleepy, sick, waking up from anesthesia, or has an eye injury.
The nictitating membrane also contains a tear gland to help lubricate the eyes. Occasionally, this tear gland will flip upward and outward (prolapse), and you’ll see a bright red, irritated-looking bulge in the corner of the eye – classic cherry eye.
Although cherry eye can occur in cats, it’s rare, and occurs much more frequently in dogs. It can affect one or both eyes. Although cherry eye looks horribly painful, it actually doesn’t seem to cause much immediate pain. However, if left untreated, the condition can create several problems – the most serious of which is decreased tear production.
The tear duct in the third eyelid is responsible for anywhere from 30-50% of total tear production in the eye, and if something interferes with its ability to lubricate the eye, the cornea (the transparent front part of the eye that covers the iris and the pupil) can become irritated. This can lead to corneal ulcers, which are not only extremely painful, but also may result in blindness. The prolapsed tear gland itself can also become inflamed and prone to infection.
What Causes Cherry Eye?
The cause of cherry eye is not fully known, but it’s thought to be a congenital (present at birth) weakness of the connective tissue and ligaments that hold the tear gland in place. Dogs usually have their first episode of cherry eye as puppies, usually before the age of 2 years.
Genetics are also thought to play a role. Although it’s not known for sure if the condition is inherited, several breeds are predisposed to developing cherry eye. Breeds most commonly affected include:
- Cocker Spaniel
- Shar Pei
- Boston Terrier
- Lhasa Apso
- Shih Tzu
- Bull Terrier
- Saint Bernard
- Basset Hound
However, any dog, of any age or breed, can develop cherry eye. Currently, there is no known way to prevent it, other than not using dogs for breeding who have experienced an episode of cherry eye in the past.
Treatment Options for Cherry Eye
Treatment for cherry eye almost always involves corrective surgery. This is because the weakness in the connective tissue around the tear gland that allowed the prolapse to happen in the first place is still present, so even if the gland is able to be temporarily pushed back into place, chances are very high that it will prolapse again.
Currently, there are 3 types of surgical methods used to treat cherry eye:
Removal of the Prolapsed Gland
This used to be the most common surgical treatment for cherry eye, but there are several problems with this technique. First, if you remove a tear gland, you are basically removing a portion of the eye’s lubrication process. This can lead to a condition called “keratoconjunctivitis sicca” (KCS), or “Dry eye.”
Dry eye is a permanent condition in which the cornea dries out. Dogs with Dry eye must depend on their guardians to manually lubricate their eyes with artificial tears daily for the rest of their lives in order to prevent permanent damage and total loss of the eye.
Obviously, preservation of the tear gland is very important! Anchoring, the second technique (which is now the most common), involves surgically placing the gland back in its normal position and suturing it back into place. However, this method is not always successful, and some dogs will have a recurrence of the prolapse even after surgery. Additionally, the suture material used to hold the gland in place may irritate the eye and cause problems.
The Modified Morgan Pocket Technique
This relatively recent technique involves the creation of a new “pocket” of tissue to hold the gland in place. Not only does it have a higher success rate than simply suturing the gland back into place (a less than 10% chance of the prolapse recurring, compared to around a 20% chance of recurrence with the anchoring method), it is a relatively quick and simple procedure, resulting in less time under anesthesia and less risk for the patient.
General veterinary practitioners, veterinary surgeons, and veterinary ophthalmologists are all able to perform surgery to correct cherry eye. However, keep in mind that veterinary ophthalmologists have advanced training and certification, and because of their greater experience in surgically treating cherry eye, their patients tend to experience a lower risk of the prolapse returning after surgery.
To learn more about veterinary ophthalmologists, you can visit the American College of Veterinary Ophthalmologists website.
A Quick Word About Home Treatment
If you search online, you will find no shortage of home remedies for cherry eye. These include natural cures such as herbal eye drops, along with massage techniques, recommendations for how to manually push the prolapsed tear gland back into place, and the application of ice packs to the eye to reduce swelling.
There are several risks involved with attempting to treat cherry eye yourself. First, when you attempt to manually reinsert your dog’s prolapsed tear gland, you run the risk of damaging not just the gland, but injuring the eye itself. Trying to do anything around such a delicate area while a dog is squirming in your arms is a recipe for disaster.
There’s a reason the tear gland prolapsed, and it’s because of an underlying weakness in the connective tissue around the gland. Even if you are successful in manually manipulating the prolapsed gland back into place, the risk of the gland popping back out is extremely high. In a recent study, only 20% of dogs with cherry eye were able to have the gland manually reinserted by veterinarians, and of that 20%, 80% of them eventually needed surgery.
So if your dog or cat experiences cherry eye, your best bet is to have them seen by a veterinarian to assess their condition. In this case, the old tried-and-true adage applies: please don’t try this at home!
Cherry eye is a condition that needs to be addressed as quickly as possible. The longer the tear gland is prolapsed, the greater the risk of associated problems, including restricted blood flow to the gland, decreased tear production, swelling, and inflammation. This inflammation can cause the pet to paw, scratch, or rub the eye, leading to the risk of infection.
A pet who has had cherry eye in one eye is at high risk for developing it in the other eye as well. Even though cherry eye may recur after surgery, the risk is small with the proper surgical technique. If your dog or cat develops cherry eye, it’s important to see your vet as soon as possible to begin the necessary treatment to restore your pet’s eye health.
Have you ever treated a dog or cat for cherry eye? Please tell us about it in the comments below!