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Third Eyelid Showing in Cats - Causes and Treatment

By Josie F. Turner, Journalist specialized in Animal Welfare. Updated: October 16, 2018
Third Eyelid Showing in Cats - Causes and Treatment

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Cats' eyes can be truly fascinating for those who take their time to look into them. Not only due to the fabulous combinations of colors, but also due to the unusual behavior of their pupils, which change in size depending on the amount of light in the environment. Their eyes are so well known for their distinctive appearance, reflection spots on roads are known as cat's eyes.

A cat's eye contains an inner membrane known as the third eyelid. This is to differentiate it from the outer eyelids. You may have never seen it, as doing so is a sign of a health problem. As such, if you've recently noticed it, you will need to read up on the causes and treatment for a third eyelid showing in cats. Fortunately, AnimalWised provides the information to do so. It is a symptom of a heath problem in your cat and should not be ignored under any circumstances.

You may also be interested in: How To Clean Dog’s Eyes

What is the third eyelid?

The scientific name of this membrane located in the eyes of most mammals, including cats, is Tertia palpebra. More commonly it is known as the third eyelid or nictitating membrane. It is a tissue located around the cornea, conjunctiva and mucous membrane. Although it isn't commonly spotted, you might notice some secretions between the eye and the outer eyelids when your cat is half asleep. As they wake up, a cat's third eyelid showing as they begin to open their eyes is normal. However, it should not be visible once open, awake and alert.

The role of the third eyelid is to protect the eyeballs from any foreign object and from traumas as a result of a hit or knock. It is also responsible for releasing a liquid, whose antiseptic properties are capable of fighting against the presence of bacteria and microorganisms that could cause disease. However, these protective uses of the third eyelid should not lead to the feline nictitating membrane to show all the time.

Nictitating membranes are also sometimes known as a 'haw'. In other animals, including many birds, it can be used to moisten the eyeball while open. As it is transparent or translucent, it means the animal can still see. Some mammals have a full third eyelid which can do this, but the cat does not. It is believed that some species have evolved away from using this membrane. Even humans have a vestigial part of their conjunctiva known as the plica semilunaris which is thought to have once been a third eyelid.

If you see that your cat's third eyelid is visible, either in one eyeball or in both, this means that they are in pain or suffering from a condition or disease[1]. Some research suggests that the appearance of this membrane is related to intestinal parasites and digestive problems, whereas others state that if this membrane is visible then the problem is related to the eye itself. In these latter cases, the problem with the cat's inner eyelid could be due to a prolapse[2]. In order for you to have all the information, we will show you the causes that can cause this tissue to appear in your cat's eye.

Third Eyelid Showing in Cats - Causes and Treatment - What is the third eyelid?

Causes of third eyelid showing in cats

If you see that your cat's nictitating membrane is visible in one or both eyes, it is usually a symptom of a secondary problem. These are some of the root causes of third eyelid showing in cats:

  • Conjunctivitis: this ocular infection doesn't only cause the appearance of the third eyelid, but is also causes swelling, tearing and lacrimation.
  • Dehydration: when the cat is suffering from a severe lack of water, the appearance of this ocular tissue is a sign and symptom of a serious health condition. It will need to be treated by a specialist.
  • Wounds: if your cat has suffered a blow or trauma to the face, both of its eyes may have become affected. Take them to the vet straight away.
  • Foreign body: anything that gets into the cat's eyes, whether rubbish, dust or something else will cause this membrane to appear, as it is a mechanism to prevent it from further imbedding into the eyeball.
  • Cancer: it's possible for this small organ to be affected by the formation of cancer cells. Fortunately, the disease is relatively rare in this part of the eye. Unfortunately, if it does occur, then it can progress quickly and become fatal[3].
  • Haw's syndrome: this name is given to the appearance of the third eyelid when related to an intestinal problem that the cat is suffering from, or has suffered from recently, whether intense diarrhea or the presence of parasites. With Haw's syndrome in cats, the third eyelid turns into a protrusion thanks to prolapse. it most commonly occurs in cats less than 2 years of age. Prolapse of the nictitating membrane is one of the most common issues with third eyelids in dogs[4].
  • Genetics: some cat breeds, such as the Burmese, might be prone to suffering a rupture or protrusion of this membrane inside the eye, which is very uncomfortable for them.
  • Dermoid cyst: a dermoid cyst is one which is present at birth and can grow slowly as they age. It is usually not observed until secondary symptoms occur. One case study on a kitten with third eye showing from 2016 shows that it can be present on any part of the eye. The result is still protrusion of the nictitating membrane[5]. However, the same study notes that any ocular dermoid occurs infrequently and can respond well to treatment.

Furthermore, if you see the third eyelid in your cat it is also highly likely that its eyes will start to lacrimate. They will probably try to touch them with their paws owing to the discomfort caused when this membrane is out of place.

Third eyelid showing in one eye

As a note, if a cat's inner eyelid is showing in one eye and not the other, it is still a cause for concern. It may imply a problem on one side of the body, but it still means there is an issue which needs resolving. It might be that you see a cat's third eyelid showing in one eye which progresses to both. This implies the progression of one of the causes listed above.

If a cat third eyelid showing in one eye is observed, it could be some direct damage to this membrane. This would explain why it is visible in one eye and not the other. It could be a piece of dust which has lodged within or even something hitting it. As we have stated above, cancer is a possible cause of protrusion in the third eyelid, but this is relatively rare. Regardless if a cat's nictitating membrane is observed in one eye or two, you should take them to the vet for evaluation.

Third Eyelid Showing in Cats - Causes and Treatment - Third eyelid showing in one eye

Treatment for a third eyelid showing in cats

Owing to the various reasons that can cause the cat's nictitating membrane to occupy more space in the eye than it should, there are several types of treatment. This treatment depends on the source of the problem.

In the case of dehydration causing your cat's third eyelid showing, you should give the cat plenty of wet food and water in order to halt the process. It is also recommended to take the cat to the vet, as the animal has been lacking water for too long to be treated at home. Many treatments for a third eye protrusion

In the case of conjunctivitis, wounds, foreign bodies in the eye and cancer, only the vet's diagnosis will be able to determine the next step to follow. They might be prescribed eye drops and other medications in the first 3 problems, depending on the severity. If they have cancer they may be recommended surgery and/or radiotherapy. Surgical removal may occur if there is a benign tumor on the cat's inner eyelid. Only the specialist can decide on the best option to conserve the cat's health and quality of life. As the cat recovers, their inner eyelid should start to retract.

Haws syndrome should disappear by itself, once the intestinal and digestive problems that caused the appearance of the membrane go away. This, in turn, will lead to the nictitating membrane gradually disappearing as the cat returns to health.

When a genetic reason is behind it, the vet will use medical studies to determine whether the cat's inner eyelid membrane is affecting the cat's vision and causing discomfort. If this is the case the vet may also resort to surgery. This process will not to extract their third eyelid, but will put the feline nictitating membrane back into its correct position. If there are any other infections or conditions causing a cat's third eyelid to show, they will be treated accordingly.

If you want to read similar articles to Third Eyelid Showing in Cats - Causes and Treatment, we recommend you visit our Eye care category.

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Alex
Hi! After a brief nap today with the kitties I suddenly noticed Zelda's left inner eyelid wasn't fully retracting. She was fine all day up until now. At first I just assumed she hadn't fully woken up yet, as I know that's normal to see the eyelid when they first wake up, but then she started rubbing her eye and I knew something was up.

She and her brother are very well hydrated. They drink their water and I feed them wet food twice a day, so I don't think hydration is the issue. If I had to guess, something must have gotten into her eye.

Do I need to take her to the vet or does this sort of situation resolve itself with time (like within 24 hours)? Thank you!
Administrador AnimalWised
Hi Alex,

It is possible there is something in her eye which has agitated the third eyelid. However, it is also possibly the beginning of an infection or some other issue. Unfortunately, we could not possibly diagnose this problem ourselves, nor can you. Only a qualified vet can do this. If it has not cleared up on its own and you see other symptoms appear, it is very important you take them to get checked. Good luck, we wish Zelda all the best!
romina
I was laying next to my cat and she was sleeping then the third eyelid started showing but as soon as she woke up it was gone is this bad? or does it just happen when your cat is sleeping?
Administrador AnimalWised
Hi Romina,

This is a good question. When a cat is closing its eyes to sleep, you can often see the third eyelid, it is just a natural action. If it is not displayed when the cat is asleep, they should be fine. However, if you are in any doubt or they are showing other symptoms, you should take them to the vet. Hope this helps!
Michael marocco
My cat has the third eyelid showing my cat is vomiting, refusing to drink, not moving much we do not know what to do or what he has
Administrador AnimalWised
Hi Michael,

Neither do we as it could be a wide range of possible issues. What we do know is that your cat is showing signs of potentially serious illness. You need to take them to the vet immediately if this is the case.
Sherry
This is my adorable, handsome lil man. I love this baby to the moon and back. He is my heart and my world. The world revolves around him in my eyes. He is very loveable and playful, eats like a pig and sleeps on my chest every night. Well, not long ago he developed some sort of eye infection in one eye and soon spread to the other eye. There was like a yellowish looking mucus coming from his eyes and his 3rd eyelid now covers like half his eye. They were also swollen bad and red. A friend recommended terramycin so that's what I purchased. I put it in his eyes 2-4 daily and now they are no longer swollen or red nor is there any mucus coming from his eyes but the 3rd eyelid is still covering half his eyes. Any suggestions on what to do next? Thanks in advance.
Administrador AnimalWised
Hi Sherry,

You should not treat eye infections like this on your own. It requires the diagnosis of a professional. If you are fortunate and the terramycin has worked, it is possible the infection is on its way out. However, the cat may need different types of antibiotics or the red eye is the symptom of a different disease. We cannot diagnose it here, so we recommend taking them to the vet to be sure.
Jb
My cat had a complete tooth extraction 2 months ago . She has been doing just fine until this last week. One side of her face has began to swell and her 3rd eye is showing. She still has a appetite but many times when she eats the food falls out of her mouth. Is there anything I can do to help her? What may be causing this?
Administrador AnimalWised
Hi JB,

You should take them to the vet. Inflammation implies infection, so they will likely need antibiotics. Whatever is the issue, they will need a vet to confirm the diagnosis.
Luke Goulden
Can anyone recommend a brand of drops that will help with this? We have 3 cats all of which have never had such symptoms but all are showing it all of a sudden. Thanks Luke
Melanie Newington
My cat had an eye infection and the 3rd eyelid was showing. I felt extremely concerned. After 2 courses of eye drops, improvement was still very slow. It has taken over 6 weeks to get back to normal, what a relief! Sometimes nature has to run its course.
Administrador AnimalWised
Hi Melanie,

We have many comments from people who have experienced the same situation. Unfortunately, convalescence isn't an instantaneous process, sometimes these things take time. As hard as it can be to have patience, it is a necessity sometimes.
Jason O
My cat ever since I got him as a kitten about (6 months old) from a local petsmart has always had this problem in one eye and has never shown any signs of discomfort, pain, or anything like that. Quite the Opposite actually he’s a playful happy healthy sweetheart but I’ve always wondered why his eyes like this. It really doesn’t seem like it could be anything on the above article because he has no symptoms of being sick or uncomfortable. The only reasonable explanation above is he had some sort of trauma before he was adopted by me. So I guess what I’m wondering is if that’s even the cause what kind of treatment can he get or what can I do for him?
Administrador AnimalWised
Hi Jason,

It is indeed possible that your cat has had some sort of trauma, but it is impossible for us to tell though these comments. It is also possible that the cat has a disease which is otherwise asymptomatic. This means there could be a problem, but you won't know it until the disease has progressed far enough. One such disease is chronic kidney failure. You should be taking your cat to the vet for regular checkups (once or twice a year). If they are due, you should take them along and find out just to be sure. They may need to run blood tests or other diagnostic tools.
Shannon J Rothberg
We have a few cats who have all developed some issue with their 3rd eyelid showing (where it had not been in the past). Our vet was no help. The cats (3 cats) otherwise seem fine. No parasites in the litter box. All indoor cats. One cat has loose stools (all her life - she is 2yrs old) Obviously the issue is due to something contagious. Any ideas? Thank you!
Administrador AnimalWised
Hi Shannon,

We cannot diagnose anything in these comments. We can maybe suggest something, but if your cat is unwell, you will need to see a vet. Particularly with a third eyelid showing, the causes are various and many conditions share symptoms. If you are unhappy with your vet's advice, you should get a second opinion and explain your situation. We're sorry if this isn't the answer you are looking for, but it would be irresponsible of us to provide another one.
Gen
Please help. My cat has had third eyelid showing for 5 days. Taken to vets and initially was due to bad allergies (which are cleared now) but the eyelids are still showing and seem to be getting worse. They are almost covering entire eye. We are giving him eyedrops (vet subscribed) but no impact. We have also been back to the vet twice (different vet 3rd time) and they have given him the all clear for other health conditions that could be causing it. Am I being impatient? Should the eyelids be back to normal by now?
Administrador AnimalWised
Hi Gen,

If your cat's third eyelid is showing, they will need a physical examination by a veterinary medical health professional. Since you have been to the vet 3 times and have had a second opinion, then this will imply you will need to wait for the symptoms to go down. However, this is only a suggestion, it is possible these vets have missed something, but we would think it unlikely. Keep an eye on related symptoms and if they seem to be getting worse in general then the only thing you can do is take them to the vet.
Melanie
My cat had an eye infection and the 3rd eyelid was showing. After visiting 2 different vets and 2 lots of eye drops, improvement was really slow. I have been very concerned. After 6 weeks things are looking normal again. I think sometimes nature has to run its course and heal naturally.

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