Dogs possess a third eyelid, known as the nictitating membrane. This eyelid sits diagonally in the inner corner of the eye. The eye is lubricated by tear film, which consists of water, oil, and mucus. Each eye has two glands, one just above the eye and one located in the third eyelid. The gland in the third eyelid is believed to produce between 30 and 60 percent of the total tear film water; so it is important to maintain this gland's function. This article describes a condition that affects the function of the third eyelid gland, which can ultimately cause a reduction in tear film.
In the normal dog eye, you may occasionally get a glimpse of the third eyelid. It may be visible when your pet sleeps or wakes from a nap. Some owners may notice it after their pet has had surgery and are recovering from the anesthesia. When the third eyelid gland thickens and slips out of its proper place, owners will notice a red swollen mass next to the lower eyelid. This leads to the term "cherry eye."
Cherry eye is seen in young dogs, six months to two years of age. The most common breeds affected are cocker spaniels, bulldogs, beagles, bloodhounds, Lhasa apsos, mastiffs, Shih Tzus, and other brachycephalic breeds. Cats are rarely affected, but it has been reported in Burmese and Persian breeds. Unfortunately, cherry eye is not preventable. Knowing what signs to look for can aid in quick diagnosis and treatment.
- Oval swelling protruding from the edge of the third eyelid
- May occur in one or both eyes
- Epiphora (excessive tear production)
- Inflammed conjunctiva
- Blepharospasm (excessive squinting)
- Dry eye
A red swelling protruding from the edge of the third eyelid is usually the first sign of a cherry eye. This may occur in one or both eyes. Some dogs may not have any other symptoms. Others may have increased tear production, inflamed conjunctiva (a clear mucous membrane that lines the inner surface of the eyelid and the exposed surface of the eyeball), and ocular discharge. If there is a reduction in tear formation, they may experience dry eyes which can cause discomfort.
If you notice your dog pawing at its eyes, or rubbing its face on the floor or carpet, this is a sign there is a problem and you should seek veterinary attention.
It is not fully understood what causes cherry eye. We do know the lacrimal (tear) gland of the third eyelid is held in place by tissue fibers. Some dogs have weaker fibers so the gland protrudes. In smaller breeds, especially Boston terriers, cocker spaniels, bulldogs, and beagles; the gland of the third eyelid is not strongly held in place because of genetic reasons. When the gland prolapses, it does not circulate blood properly. This results in swelling and the gland may not produce tears normally.
When a cherry eye is first diagnosed, your veterinarian may recommend a course of anti-inflammatory eye drops, to help reduce the swelling. Antibiotic eye medication may also be prescribed, if there is an associated discharge. If the cherry eye persists and causes discomfort, surgery will be the next step. The best treatment involves replacing the gland back in its proper location. However, when this is unsuccessful, the gland itself may need to be removed.
The traditional tucking method (also called tacking) is probably most commonly performed. This technique requires permanently placing a single stitch, drawing the gland back where it belongs. Complications are uncommon but can occur.
- The tuck may not be anchored well enough to hold permanently. This is the most common complication. A second or even a third tuck may be needed. If this fails, another procedure may need to be used.
- The surface of the eye can become scratched if the stitch unties, causing pain for your dog. If this happens, the stitch can be removed, but the cherry eye may return.
- Sometimes the cherry eye is accompanied by other eyelid problems that make the repair more difficult, or less likely to succeed. In these cases, a referral to a veterinary ophthalmologist may be necessary.
Imbrication, or pocketing, is a newer technique. A wedge of tissue is removed from directly over the actual gland. This method poses more of a challenge, because it is often difficult to determine how much tissue to remove. Tiny stitches are used to close the gap. Tightening of the incision margins pushes the gland back in place. The stitches eventually dissolve. Complications can occur including:
- Inflammation or swelling as the stitches dissolve.
- Inadequate tightening of the tissue gap may lead to recurrence of the cherry eye.
- Failure of the stitches to hold and associated discomfort. Depending on the type of suture used, loose stitches can injure the eye.
Sometimes, both tucking and imbrication are used to repair the cherry eye. Your veterinarian will determine which method is the best one to use.
Removal of the gland of the third eyelid used to be the most popular remedy for cherry eye. Now that we know the full significance of this gland, to produce tear film, this is not the preferred treatment. If the third eyelid gland is removed, and the upper eyelid gland fails to produce adequate tears, a thick yellow discharge results. If this happens the eye develops a blinding pigment covering for protection. This condition is called keratoconjunctivitis sicca, or simply, dry eye. Dry eye usually requires lifelong medication. If left untreated, blindness can occur.
How to Care for a Blind Dog
Postoperative swelling is very common after cherry eye surgery. This should resolve in about a week. If the eye becomes suddenly painful or unusual in appearance, recheck it as soon as possible. It is not uncommon for the cherry eye to return. To avoid prolonged recovery and complications, make sure you follow all of your veterinarian's post-surgery instructions.
If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.
Unlike humans, dogs actually have three eyelids rather than two – the additional eyelid sitting under the inner corner of the eye. “Cherry eye” is the colloquial term for prolapse of this third eyelid. It can be readily diagnosed upon visual inspection, as a small pink bulge in the inner corner of the dog’s eye. Cherry eye occurs when the tear gland within this (usually hidden) 3rd eyelid, becomes swollen.
Certain breeds of dogs are predisposed to cherry eye and whilst the cause of this condition is not fully understood, there may be a genetic predisposition to its development. Whilst the condition is not likely to be uncomfortable, the tear gland within the third eyelid is crucial to maintenance of eye health. Prompt veterinary advice must be sought with a case of cherry eye, to prevent unnecessary long-term damage.
No prevention is known to exist, however with the appropriate surgery, the condition can usually be successfully treated.
Which dogs can be affected and when?
Symptoms of cherry eye will normally arise in young pets that are less than 2 years of age. As mentioned above, certain breeds are predisposed such as Beagles, Pugs, Boston terriers, English Bulldogs, Cocker Spaniels, Cavalier King Charles Spaniels and West Highland White Terriers. Occasionally the condition may be seen in cats too.
The exact cause of cherry eye remains incompletely understood, however the association with certain breeds of dogs, and other research, suggests in part at least, that a genetic predisposition may exist. Practically speaking in this condition, the third eyelid fails to maintain its usual position within the eye. This may have a possible link and association to defects in connective tissue or associated ligaments. Excitement and shock may also play a predisposing role in some individuals.
Medical treatment: unlikely a solution
Whilst certain medications may be prescribed to help treat cherry eye, ultimately, in nearly all cases, surgery is required. Your vet may temporarily prescribe topical lubricant medication to keep the eye and third eyelid moist and hydrated. Topical antibiotics and anti-inflammatories will treat any associated infection and pain/inflammation respectively. Infection and inflammation should be controlled ahead of surgical correction.
Surgical options
Over the years many different surgical techniques and methods have been employed to treat cherry eye in dogs. What we crucially understand now however, is the essential need to use a surgical technique that accurately replaces and anchors the third eyelid gently back into its usual location, rather than to just excise (chop out!) the eyelid. Surgical replacement offers optimal care to preserve the tear production within the gland. Conversely, if the gland is removed, there is a significant chance of dry eye (keratoconjunctivitis sicca), developing in the eye. This is both a painful and sight threatening condition for the dog and can be an expensive problem to treat.
Surgery should be carried out as soon as possible.
The longer the third eyelid remains prolapsed, the quicker fibrous tissue develops within the gland. Tear production and function will be correspondingly reduced.
Nowadays there are 2 or 3 favoured surgical techniques that can be used to treat cherry eye.
Often, the gland is sewn back into a pocket inside / behind the third eyelid
This method has high success rates. Your vet may be happy performing this themselves in first opinion practice, albeit may also offer referral to a specialist ophthalmologist for the procedure. Any of the techniques utilised, will be performed under general anaesthesia, probably with operating magnifying glasses. It is essential to ensure that the tissues are handled in a delicate, sympathetic and gentle manner.
Whilst success rates are typically good, there is always a small (approximately 10%) risk, of recurrence of the condition. This is not uncommon and will require a second surgery to replace the gland again.
If however, repeated surgical replacements are unsuccessful it may, rarely, become necessary to remove the tear gland entirely.
This should only be offered as a last resort option and if multiples of surgeries have failed to cure the problem. With such “salvage” surgery, the risk for your dog developing dry eye in the long-term, is significant. Your dog will need regular check-ups for this condition, so your Vet can measure the tear production within the eye over a minute, to assess for the adequacy of tear production in the eye.
Follow up post-operative care
Following any kind of ocular surgery, for the first few days, it is vital that a buster collar is worn by the patient. This prevents any unnecessary trauma (and potential wound breakdown) that your dog may inadvertently cause from trying to scratch or rub the wound. The buster collar should stay in place at all times.
Topical post-operative medications are likely to be prescribed (for those reasons stated above) and to minimise any complications associated with the surgery.
Any activities that increase the pressure within your dog’s eyes (such as vigorous playing and energetic exercise), should be avoided. Furthermore, the use of a collar and lead is discouraged, since the force on the dogs’ neck can also act to increase the pressure within the eyes. It is preferable to choose a harness instead.
Possible complications
A small possibility of course, with any surgical procedure, is the risk of complications. Cherry eye surgery is no different. These may include infection, irritation of the eye from the suture material, and as mentioned above, re-prolapse of the gland.
Additionally, if your dog has suffered from cherry eye in one eye, they are at an increased risk of developing this in the other eye.
Dry eyes
With an appropriate surgical technique for cherry eye, subsequent development of dry eye should not be a risk.
It should be noted however, that for many of the breeds described as “at risk” or genetically predisposed to cherry eye, there is also a predisposition to developing (unrelated) dry eye (usually bilaterally in both eyes) as middle-aged or older animals. This again, is thought to be attributable to a genetic predisposition, since we frequently recognise “spontaneous” dry eye in these breeds too.
However, for the vast majority of dogs, surgery remains highly successful and provides a permanent solution for treatment of the condition.
Prevention
Given that a genetic predisposition may exist, it would be a sensible precaution not to breed from any dog affected with cherry eye, for fear of producing further generations of dogs who may be affected with the condition.