Cherry eye is a condition that sounds like what it is: a cherry-red swelling that appears to sit on the eye.
This condition looks dramatic and yet it doesn’t bother the pet so much as the pet parent. But what exactly is this startling condition, and what does it mean for your dog? That’s what we’ll explore in this vet-written article.
Below are 8 big things you should know about cherry eye in dogs.
1. The “Cherry” in Cherry Eye = Prolapsed Tear Gland
So, what exactly is cherry eye?
The red swelling is a gland that isn’t normally seen because it sits snuggled up on the underside of the third eyelid. This gland’s job is to produce tear fluid to keep the eye moist and help flush away dust.
In some dogs, this gland pops out (or prolapses) from beneath the third eyelid, which is when we see it as a red swelling. For those who want to get technical, the gland’s name is the nictitans gland and the technically correct term for cherry eye is prolapse of the nictitans gland (PNG).
And for those wondering what a third eyelid is, this is an extra eyelid that cats and dogs have. It sits on the inside corner of the eye and sweeps across the eye’s surface like a gentle broom to clear away dust and debris, and serves as a protective shield. Clever stuff.
2. Cherry Eye Is Not a Cancer or Growth
As alarming as cherry eye looks, it’s reassuring to know this isn’t a tumor or cancerous growth.
It’s merely a normal tear gland sitting in the wrong place, which is then exposed to the air and becomes angry-looking as a result. In its new position the gland still valiantly works away at its job of producing 70% of the watery part of the eyes’ moisturizing tear fluid.
Cherry eye is not usually painful for the dog, even though it looks unsightly. Neither is it dangerous to the dog’s health, although complications such as a runny eye, corneal ulcers, or eye infections may develop over time.
3. Young Dogs Are Most Commonly Affected
Cherry eye is a condition that mainly affects young dogs, under 2 years of age.
You could almost say if a dog has had 2 birthdays and never had cherry eye, then your pet pal is unlikely to develop this condition. This is because some of the factors that predispose them to cherry eye are inherited and make the condition likely to show up early in life.
In fact, 83% of canine patients who present with cherry eye are less than 1 year old.
4. Breed and Face Shape Are Risk Factors
Some dog breeds carry a higher risk of developing cherry eye than others. These include:
- American Cocker Spaniel
- English Bulldog
- Great Dane
- Lhasa Apso
- Shih Tzu
- Basset Hound
- And last, but not least … Burmese cats!
Another risk factor is face shape and how snuggly the eyelids fit around the eye.
If a dog has droopy eyelids (ectropion), then by its very nature this means the eyelids, including the third eyelid, are a poor fit. When the third eyelid in particular is a bit baggy, this makes it easier for weight of the nictitans gland to push the eyelid even farther forward and then pop out of place.
5. Surgical Removal Is Actually a Bad Idea
We tend to remove lumps on dogs. Go back a couple of decades, and removal was the treatment of choice for cherry eye. It seemed obvious back then that removing the unsightly swelling would sort out the problem.
However, with the benefit of hindsight, veterinarians now know that the only benefit was cosmetic (getting rid of the red swelling) and in the long term can cause complications.
Surgically removing the prolapsed nictitans gland is a bit like turning off the water supply as a permanent fix for a leaking sink: It fixes the short-term issue but with long-term disadvantages. So, yes, the leaking sink isn’t a problem, but neither is there running water to wash the dishes. Thus, removing the gland gets rid of the ugly lump, but sadly the eye no longer produces as much tear fluid, which can lead to a dry eye.
A lack of tear fluid can tip some dogs over into a condition known as dry eye. As the name suggests, here the eye doesn’t have enough natural lubrication, which makes it hot and itchy. As well as being very uncomfortable, in an attempt to protect the eye, this leads to scar tissue and pigment forming on the clear cornea, which the impairs vision (like wearing a pair of dirty eyeglasses).
6. What Happens If Cherry Eye Is Not Treated?
If surgical removal of the cherry eye is a bad idea, then what happens if a pet parent decides to take no action at all?
In the short term, cherry eye is largely a cosmetic problem. However, with the nictitans gland exposed to the air, it dries out (in the same way your mouth dries out when you sleep with it open), which causes irritation, inflammation and discomfort. This may cause the dog to rub at the face, which then risks damage to the cornea and ulcer formation.
A sore, inflamed eye is also more likely to become infected, leading to a thick green-yellow discharge and more irritation. This leads to a vicious circle of irritation, rubbing and further damage, with the potential for permanent damage or even loss of the eye.
Also, optimal eye health depends on everything being in the right place. When in the correct position, the third eyelid protects a small reservoir of tear fluid called the lacrimal lake, which keeps the cornea moist. With the shape and position of the third eyelid distorted by the prolapsed nictitans gland, this reservoir leaks away.
One symptom of this is the eye appears teary and the dog may have a permanently wet cheek.
7. Surgical Repair of Cherry Eye
Rather than do nothing about cherry eye, corrective surgery is recommended.
But here comes a subtle difference from the past, because the surgery isn’t about removing the gland but repositioning it in the correct place, snuggled up safe behind the third eyelid.
There are a number of techniques that surgeons have developed over the years. These have one thing in common: They are variations on using fine-gauge suture material to anchor the nictitans gland into the correct position.
This is tricky surgery for a number of reasons. The first reason it’s tricky is because it means anchoring the gland to tissue deep down near the skull. Secondly, this is small-scale surgery, so it’s only possible to take small bits of tissue. That means it’s fairly easy for the suture to slip out of position post-surgery and the cherry eye recur.
Most surgeons warn of a high recurrence rate because of these difficulties. It’s not unusual to need to repeat the surgery to get a successful outcome.
8. Complications of Cherry Eye Surgery
The most common complication of cherry eye surgery in dogs is that the gland pops out again.
The failure rates vary depending on the technique but can be as high as 58%. In practical terms, this means a 1-in-2 chance of needing a repeat procedure.
As for the actual surgery, the most common complication is an ulcer forming on the corneal surface. This may happen if one of the tiny surgical knots breaks free and starts to rub on the surface of the eye. When detected early (part of the reason for the post-op checks), these ulcers can be treated.
An important part of reducing the risk of complications is that the patient must wear an Elizabethan cone until the eye has healed. Failure to do so means the dog may rub their face and dislodge the sutures, and then everything goes back to square one.
This video shows a veterinarian pushing the third eyelid back into place in the office, although this solution may only be temporary:
Final Thoughts on Cherry Eye
Let’s recap. What do we now know about cherry eye in dogs?
- The red cherry is a tear gland that has popped out of place.
- Cherry eye is not a cancer or tumor.
- Young dogs from certain breeds are most likely to develop cherry eye.
- Cherry eye looks unsightly but is not dangerous in the short term.
- Over the long term, though, the gland may become swollen and angry-looking.
- Surgical removal of the gland is not advised.
- The treatment of choice is surgical anchoring of the gland into its proper position.
- Surgery does have a high failure rate, so be prepared for repeat surgery.
If you have a dog from an at-risk breed, you should have cherry eye on your radar. And if this condition occurs in your dog, don’t panic. Instead, have a discussion with your vet about what’s best for your pet.
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