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  • Molly Weinfurter

Dog Third Eyelid: Why Do Dogs Have a Third Eyelid?

Updated: May 27

You may have heard mention of a dog having a third eyelid, but is it true? And what does it mean? There are lots of dog facts that are still unknown to the average person, even to proud dog parents. So, there’s always more to learn about our canine companions, such as their unusual eyelid setup.


Do Dogs Have a Third Eyelid?

Yes, dogs have a third eyelid. They have a top and bottom eyelid just like humans do, but then, they have an extra eyelid that's thin and swipes sideways across your dog’s eye. The third eyelid is called the “nictitating membrane” or the “nictitans.”


The third eyelid on your dog is rarely visible. Sometimes, you may be able to see part of it in the corner of your dog’s eye near their snout, but it should never be obvious. It normally only closes when your dog is napping and their other eyelids are already closed, which is why humans rarely see it.


If you've never heard of a third eyelid on a dog, that's okay. Even though I spend lots of time volunteering with dogs, I didn't know about their extra eyelids until a few months ago. Looking closely at my dog, I can see her third eyelids sometimes, but it's not something the average person would easily spot.


dog third eyelids visible

Why Do Dogs Have a Third Eyelid?

A dog’s third eyelid helps protect their eye and keep it moist. When the third eyelid slides across the dog’s eye, it spreads tear film and pushes debris out of the way. 


All dogs have them, and many other animals have them too. Third eyelids are normally on dogs unless the eyelid is constantly showing, then a health concern could be to blame.


Why is my Dog’s Third Eyelid Showing?

If your dog isn’t feeling well, their third eyelid may become elevated so it’s visible. An exposed third eyelid may indicate that your dog is dehydrated or ill. It could also be elevated because your dog is experiencing pain in their eyes. If you notice your dog’s third eyelid showing, it’s best to take them to the vet just to be safe.


A dog’s third eyelid is thin and semi-transparent, so it may be difficult to notice. Yet, if it’s elevated, you will see it bunched up in the corner of your dog’s eye. An exposed third eyelid could impact your dog’s vision. If the third eyelid appears red or pink, then that’s a more serious concern known as cherry eye.


Cherry Eye in Dogs

There’s a gland at the end of your dog’s third eyelid that helps produce tear film. If that gland pops out, you will see a squishy pink or red spot in the corner of your dog’s eye known as “cherry eye.” Even though cherry eyes are unsightly, they’re not painful for dogs unless left untreated. However, they can be uncomfortable and impact their sight.


If your dog has cherry eye, you should visit your vet immediately to determine the best treatment route. Vets used to remove the gland completely because it’s not the only body part responsible for tear production, but it’s one of the most important. So, removing it could cause dry eyes. The current recommended procedure is to replace the gland to keep your dog’s eye moist.


However, the exact treatment for cherry eye may vary from dog to dog. Your vet’s advice may differ depending on your dog’s medical history.


Other Eyelid Health Concerns

Another issue your dog may face with their third eyelid is known as scrolled cartilage or cartilage eversion. It occurs when the cartilage in the third eyelid grows too fast, causing the cartilage to be bent. Like with cherry eye, the corner of your dog’s eye will appear red and swollen. 


The cartilage is usually removed in this situation, but it’s best to ask your vet about the ideal approach. Once it’s treated, it’s unlikely to happen again in the same eye. This concern is most common in young giant breed dogs.


dog third eyelid showing

Other Animals with Third Eyelids

Humans are actually the odd ones out when it comes to eyelids. Most mammals have some type of third eyelid, also known as a “haw.” Cats, polar bears, seals, and aardvarks are just a few examples of other mammals with them. Many birds, lizards, snakes, frogs, and sharks have them too. Like dogs, these animals have third eyelids that are rarely visible, which is why people don’t know about them.


Frequently Asked Questions


Will My Dog’s Third Eyelid Go Away?

If your dog’s third eyelid is visible, it may go away on its own. Yet, if it’s stuck out for several days, you should visit your veterinarian. While it may not bother your dog at first, it could eventually irritate their eyes and affect their vision.


How Much is Dog Eyelid Surgery?

Vets typically charge between $500 and $1,500 for surgery related to your dog’s eyelid. However, the price can vary based on the situation and the vet. Talk to your vet to determine the best treatment option for your dog.


Can a Dog Get an Infected Eyelid?

Dogs can get eye infections or infections around their eyelids and tear glands. If it happens, your dog’s eyelid will likely appear red and swollen, causing them to blink or produce tears more frequently. Eyelid infections can be painful and uncomfortable, so seek veterinary care right away.


Which Dog Breeds Are Prone to Eyelid Problems?

Brachycephalic dogs, such as English Bulldogs and Shih Tzus, are more likely to have eye problems than the average dog. Some large breeds, such as Akitas, Labrador Retrievers, and Huskies, are also prone to eyelid issues.


How Can I Keep My Dog’s Eyelids Healthy?

Regularly inspect your dog’s eyes for anything unusual, such as scratches, puffiness, or excessive tear production. Clean around your dog’s eyes with damp cotton balls to prevent eye gunk from building up. If you ever have any concerns about your dog’s eye health, talk to your vet.


dog eyes close up

Dogs Have Three Eyelids

Now that you know dogs have three eyelids, you can keep up with your dog’s health better. If you ever notice their extra eyelid sticking out, it’s best to visit the vet just to be safe. Third eyelids are normal in dogs, but if they’re visible or irritated, it can be uncomfortable for your furry friend, especially if not treated.

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