We often assume our dogs are furry humans, and so they should have two normal eyelids. How many eyelids do dogs have, and what should we know about them?
You may never have considered how many eyelids your dog has until you’re faced with a cherry eye or a prolapsed third eyelid. That’s right. Third eyelid. But does that mean they have a fourth or fifth? How many eyelids do dogs have, and what’s the purpose?
Let’s take a closer look at what these eyelids do and what kind of health problems can arise because of canine eyelid issues.
How Many Eyelids Do Dogs Have?
Dogs have three eyelids in total. Like humans, each eye has a visible upper and lower eyelid with eyelashes. But they also have a third eyelid called the nictitans, or nictitating membrane tucked away in the inner corner of a dog’s eye. It is triangular, made from conjunctival tissue, and attached to a tear gland. Typically, it will sweep across the eye when the other two eyelids are closed to do its job.
You will rarely, if ever, see the third eyelid unless you gently lift one of your dog’s other two eyelids while they are sleeping. You may also catch a glimpse of it if they wake up suddenly.
This brings us to the next critical point.
Why Do Dogs Have A Third Eyelid?
The nictitating or third eyelid is critical for a healthy eye. It functions to:
- Produce a third of a dog’s tears. The membrane has a tear-producing gland that is necessary to keep the exposed eyeball lubricated. They also provide essential oxygen and nutrients to the eye’s surface. Some dogs, particularly toy breeds such as the Maltese and Yorkshire, have a problem with tears leaking down their face instead of draining away in tear ducts. This causes unsightly tear stains, most noticeable on light-colored fur. Dog eye wipes with tear stain remover are necessary to dry the area around the eyes and prevent red tear stains.
- By sliding across the eye, the third eyelid acts like a windscreen wiper, wiping away dust, pollen, or any other substance that can irritate the eyes. It also has a slimy underside that moisturizes the eyeball and spreads the tears evenly across the surface to prevent dry eye.
- The third eyelid also protects the cornea, so it is vital to prevent painful corneal ulcers.
So the third eyelid is a vital part of a dog’s anatomy. But what kind of problems may arise with it?
4 Reasons Your Dog’s Third Eyelid May Be Showing
Under normal circumstances, you should never see more than a tiny bit of the third eyelid. Unfortunately, sometimes the eyelid appears as a swollen, pink mass that spreads across the inside corner of a dog’s eye. This is most common in dogs under 18 months and certain breeds with genetic defects. Let’s look at some reasons why.
Cherry eye or a prolapsed nictitating eyelid
The most common reason you will see a dog’s third eyelid is a condition called cherry eye. This is, unfortunately, a significant issue with English and French Bulldogs. But also affects hounds and mastiffs with droopy eyes or other brachycephalic breeds or short-nosed breeds such as the Cavalier King Charles Spaniel or Pug.
When the membrane shifts from its normal position and protrudes over the eye, it can be uncomfortable for the dog. It also leads to other issues such as conjunctivitis and plenty of eye boogers you need to clean.
The tear gland may also become inflamed, red, and swollen. It is a congenital issue, so it usually happens in both eyes. Below we will briefly discuss treatment options for this problem.
Young dogs from giant breeds often develop problems related to their rapid growth. One problem that may occur is cartilage eversion or scrolled eversion. The nictitating eyelid has a tiny piece of cartilage in the shape of a “T.” This helps keep it in place. If it grows too fast, this cartilage bends or “scrolls.”
This folds the third eyelid over to become a visible mass in the eye’s corner. It is not as common as cherry eye, but it looks similar. Like cherry eye, it is a genetic problem and will probably occur in the other eye if it occurs in one.
Horner’s Syndrome & neurological problems
Occasionally neurological nerve problems can cause a dog’s facial and eye muscles disorder. Suppose you can see the prolapsed third eyelid of a Golden Retriever or Collie. In that case, it is more likely to be Horner’s Syndrome than cherry eye or scrolled cartilage.
With Horner’s Syndrome, usually, only one eye may sink in the socket. The upper eyelid may droop, and the third eyelid usually protrudes. This could be caused by nerve damage from an injury or even by a common ear infection. So keep this in mind when keeping your dog’s ears clean.
Dehydration can also be behind Horner’s Syndrome, so keeping your dog cool on a hot day and always providing fresh water is essential.
Third eyelid protrusion as a result of other disorders
Sometimes third eyelids protrude because of other issues. An injury could damage the tendon that is holding the eyelid in place. An allergy could also cause it to swell and become visible.
Unhealthy or sick dogs also may develop a prolapsed third eyelid. Skinny, malnourished, or dehydrated dogs can often have a visible third eyelid as a part of their overall bad health. Any condition that affects the muscles of a dog’s face can also cause the problem.
So how do we treat third eyelid problems?
What Do I Do If My Dog’s Third Eyelid is Showing?
If your Bulldog or similar breed is showing signs of cherry eye, you must act as quickly as possible. If you catch it early, you can massage it back in place. The video below demonstrates how to do this. However, always consult your veterinarian first because in severe cases, they will need to perform surgery. They will either replace the gland or suture the eyelid back in place.
In the past, it was common practice to remove the eyelid altogether. However, since the third eyelid is vital for your dog’s healthy eye function, this is an extremely cruel practice. If your veterinarian or anybody else suggests this procedure, immediately seek another opinion.
If your giant breed puppy develops scrolled cartilage, they will also need an operation. In this case, the vet will simply remove the abnormal cartilage.
In the case of third eyelids visible in less typical breeds, such as Golden Retrievers, the vet needs to conduct full tests to look for underlying causes, particularly neurological disorders such as Horner’s Syndrome. If there is no major pathological issue, they may prescribe some eye drops, and the condition should resolve within 4 months.
Now that you know more about a dog’s eyelids, have you ever considered their eyebrows? See this article on whether dogs do, in fact, have eyebrows.
Third eyelids are a part of a dog’s anatomy we rarely consider. After all, we often think of our dogs as furry humans and assume they just have two eyelids as we do. But the third eyelid is crucial to a dog’s health. We must be aware of what it might mean if they are visible and protruding and what we should do about it.
Tamsin De La HarpeAuthor
Tamsin de la Harpe has nearly two decades of experience with dogs in rescue, training, and behavior modification with fearful and aggressive dogs. She has worked closely with veterinarians and various kennels, building up extensive medical knowledge and an understanding of canine health and physiology. She also spent two years in the animal sciences as a canine nutrition researcher, focusing on longevity and holistic healthcare for our four-legged companions.
Tamsin currently keeps a busy homestead with an assortment of rescue dogs and three Bullmastiffs.
Got Questions? Video A Vet 24/7, Any Time, Anywhere 🌎
Vetster connects pet owners to thousands of licensed veterinarians ready to provide the best online vet services through video chatBook an online vet now