‘Cherry eye’ is a descriptive term which was first used because it appeared as though affected dogs had a bright red, shiny cherry at the corner of their eye. While (unsurprisingly!) these dogs do not have small pieces of fruit on their face, they do have a disorder of their third eyelid, or nictitating membrane, whereby it protrudes and does not go back in. The swelling is seen at the medial potion of the eye – that portion which is closest to the nose.
Younger dogs tend to present with this condition and certain breeds are over-represented. It would be unusual for an animal over the age of two to get a cherry eye for the first time. Though it can potentially occur on one side only, many dogs will eventually develop cherry eye in both of their eyes. While rare, it is even possible for cats to develop this condition; though it is seen much more commonly in our canine companions.
What Is Cherry Eye
Closeup of cherry eye
When the third eyelid is not anchored in as it should be, it prolapses and becomes visible to the outside world. Visible as a fleshy mass of tissue, many mistake cherry eye for an inflammatory process, infection or even a tumour.
The third eyelid is a normal part of the canine anatomy that acts as a sort of ‘windshield wiper’ that can clear away dust and other small particles from the surface of the eye. As well as this, it contains a gland which produces a constant flow of tears to maintain normal eye lubrication.
What Are the Causes?
Brachycephalic breeds like the French Bulldog are prone to Cherry Eye
Experts are not yet sure what the driving factors are exactly but, for some reason, the connective tissue holding the third eyelid in place becomes weakened and lax and allows it to move from where it should be. As is the case with many conditions where we are unsure of the cause, quite a number of theories have been proposed, including reactions to parasites, infections and even allergies and auto-immune disorders. For some, it can be secondary to trauma.
Though we may not yet be able to pinpoint the exact mechanism behind a cherry eye occurring, we do now that the defect appears to be inherited and there is a known genetic component. Similarly, we also know that it is a congenital issue; meaning pups are born with the tendency to develop the cherry eye, rather than developing it later in life.
Which Breeds Are Likely to Have Cherry Eye?
The classic breeds associated with cherry eye are those brachycephalics, such as the French Bulldog, Shih Tzu and Pug. It is also seen in breeds such as the Bloodhound and Basset Hound, who are known for having ‘droopy’ eyelids. It should be mentioned, however, that absolutely any breed, or mixed breed for that matter, can develop a cherry eye.
What Are the Signs & Symptoms?
Unlike many other medical conditions, cherry eye is immediately obvious to anyone who sees the dog. The bulbous, red mass coming out of the eye is impossible to ignore! As well as the appearance of tissue that was not there before, dogs may have watery and irritated eyes.
It is not uncommon for a secondary infection to also be present, so some will have thick, green discharge and blood-shot eyes that they squint closed. A number of dogs may even paw at their eye or rub their face on the ground because they are so uncomfortable.
Does Cherry Eye Cause Pain?
While cherry eye itself is not a painful condition at all, many dogs that present to the vet clinic will have some degree of ocular discomfort or pain secondary to other issues associated with the protruded gland. This may be due to an associated infection or the occurrence of a ‘dry eye’.
Eyes can dry out because they are no longer receiving the same amount of tear film and lubrication that they would have when the nictitating membrane was functional. A dry eye, as one can imagine, feels scratchy and uncomfortable. If the cherry eye is left untreated for too long, the third eyelid itself becomes irritated, dry and swollen.
How to Treat Cherry Eye
There can be a temptation to leave a cherry eye untreated, as initially the dog does not seem too affected by what is happening and will go about its daily life as if nothing is different. Many mistake it for a cosmetic problem. However, over time, we know that these dogs go on to develop complications.
Due to this, it is always advised for a cherry eye to be treated rather than ignored. The sooner we start treatment, the better the prognosis as delaying therapy can complicate matters.
Visiting Your Veterinarian
At the first sign of anything ‘not right’ with the eye, it is essential to bring a dog to the vet. Our pets only have two eyes and it is never wise to risk their vision! As there are other things that can mimic cherry eyes (including growths, foreign bodies and inflammatory conditions) it should never be assumed that a dog has cherry eye and a professional opinion must always be sought.
Vets will examine the eye closely to ensure that the tentative diagnosis of cherry eye is correct. They may perform a stain known as a ‘Fluorescein Dye Test’ to rule out any corneal ulcers. They will likely also check the tear production with a ‘Schirmer Tear Test’. On top of this, the eye will be flushed thoroughly with saline to check for any foreign bodies, such as grass awns or seeds. All of these tests can be done quickly and easily during a routine consultation.
Non-Surgical
In very young dogs who may not yet be good anaesthetic candidates, or in those with minor protrusions of the eyelid, medical management may be attempted first. This consists of eye drops which usually contain antibiotics and anti-inflammatories.
Some vets will advocate a type of gentle ‘massage’ that can be carried out routinely by the owner at home, in an attempt to replace the eyelid back into its normal position. In some instances, very small prolapses may correct themselves with time, although this is not often the case.
Surgical
For many, surgical therapy is the gold standard and this is particularly true for patients with large cherry eyes. Over the years, there have been several surgical procedures that have been used with varying degrees of success. The option of cutting out the prolapsed portion of the third eyelid used to be seen as a good solution, but we now know that this reduces tear production significantly (by around 30%) and can result in a dog developing ‘dry eye’ when older.
Though this surgery did provide a good ‘aesthetic’ resolution, it is no longer advised by most. Nowadays, vets will tend to either ‘anchor’ the gland back in place or to create a little pocket, to enclose it back inside. Both of these more modern methods ensure that normal tear production prevails and the cherry eye is dealt with.
Is It Likely to Reoccur Once Treated?
Unfortunately, cherry eye is not the simplest of defects to correct and it is not unheard of for both medical and surgical treatment methods to fail. This is especially true if the cherry eye has been present for a long time, if there are any co-morbidities present or if the gland itself is very large. Where medical management fails, surgical intervention is typically advised.
If a surgery is not successful, a repeat surgery will usually resolve the issue. To reduce the incidence of post-surgical complications and recurrence of the cherry eye, owners should always follow the post-operative instructions closely. Typical post-op discharge instructions usually suggest that the dog is strictly rested, wears an Elizabethan collar at all times and is provided with medicated eye drops for a week or two.
Can You Prevent Cherry Eye?
As we are not too sure what causes cherry eye, there is no way of preventing a pup from going on to develop it. However, because we do know that it is a genetic disease, controlled breeding programmes can significantly reduce the incidence of this disease within the population. By neutering all affected animals and not breeding from them, we can dramatically control the number of cases occurring within a short period of time.