Did you know that cats have a third eyelid? Seeing your cat’s third eyelid can come as a surprise, especially if you had no idea that felines have a third one in the first place! It is normal for this eyelid to show occasionally and it is nothing to worry about. However, if you see your cat’s third eyelid showing and they’re lethargic, you have every right to be concerned.
This usually indicates some type of eye condition that might need looking at by a vet. Feline eye conditions are a sensitive topic because not many people are familiar with them or talk about them. But they can be serious and we want our cats’ vision to be at its best!
In this article, I’ll talk about third eyelids, their role, when they appear, the conditions that can cause appearing third eyelids, and the treatment options available. Keep reading to find out all about this membrane and whether or not you need to take your cat to the vet.
What Is A Cat’s Third Eyelid?
All cats and most mammals have third eyelids, but most people don’t even know about this membrane. This is because under normal circumstances it isn’t visible. A third eyelid, also known as palpebra tertia, is a membrane located under the eyelids. It sits around the mucous membrane, cornea, and conjunctiva.
This eyelid acts, referred to as a nictitating membrane, acts as a protective member. It covers the feline’s cornea and goes over it like a windshield wiper to remove dirt, debris, pollen, and other particles that can cause harm. In addition, this membrane moistens the eyes, helping them eliminate potential irritating particles.
Another reason why these lids are essential is that they produce a liquid that has anti-bacterial and anti-microbial properties. In other words, they fight harmful microbes that can cause eye inflammation. Although the membranes are so helpful, they still shouldn’t show in normal conditions.
Unlike felines, humans don’t have third eyelids. So, how are our eyes different and why don’t we need this extra layer of protection? Well, according to the experts, this is because cats walk much closer to the ground than humans. Therefore, their eyes are exposed to more debris, particles, grass, thorns, and dirt. They need the added layer of protection a lot more than we do.
Besides, pet owners know how active their gorgeous furry buddies can be, especially when you let them outside. They move at high speed in the grass, climb trees, and run around without being too careful of their surroundings. As you can imagine, their eyes are constantly at risk, so the third eyelid ensures that their eyes stay unharmed.
When the eyes are open, you can’t see the third eyelids since they are retracted in the corners of the eyes. However, when your cats are very relaxed, taking a comfy nap, or once they start waking up, you might see these lids, but for a very short time. If the cat is awake and alert, the lids are carefully hidden in the inner corners of the eyes.
Why Is My Cat’s Third Eyelid Showing?
As I already mentioned, you can’t usually see a cat’s third eyelid when your furry friend is awake and alert. However, you might notice it when the cat is very relaxed, asleep, and just waking up; it’s normal to get a peek of the membrane. But you can expect it quickly disappear again within moments and, as long as your cat is healthy, it won’t appear while the cat is awake.
Every other situation, especially if other symptoms follow it, is concerning and a reason to call your vet. However, even if your cat’s third eyelid is showing and they have no other symptoms, you should still consult a doctor, and get professional help.
In most cases, a visible third eyelid is a sign of illness or a medical condition that requires treatment. Below you’ll learn more about the common conditions that cause the membrane to be visible and the accompanying symptoms you should know about.
Is your cat not eating or drinking for 3 days? Cat dehydration can happen due to excessive water loss or if your feline hasn’t been drinking water for days. This is when you might see the infamous third eyelid, and it’s not a good sign. Your furry friends need water to function! The lack of water causes their eyes to dry out, so the third eyelid comes out to help lubricate it.
You should suspect dehydration if you ever see your cat suddenly lethargic and weak. Pale gums, panting, third eyelids showing, dry skin, and sweating are other symptoms to watch out for. You have to call the vet right away, and they’ll do all the necessary tests to discover the underlying cause.
Cats might be dehydrated simply because they haven’t drunk enough water and don’t like their water setup. It can also happen because of vomiting, high fever, and high temperatures. Moreover, dehydration can be an accompanying symptom of many underlying diseases such as diabetes and kidney disease.
Your vet will give your cat the fluids required to bring her back to life. Where an underlying condition is responsible, your vet will work towards treating this instead. Or in cases where your cat is finicky with drinking, I recommend investing in a cat water fountain to encourage them to take a sip.
Also known as pink eye, conjunctivitis is caused by inflammations of the conjunctiva. This is another mucous membrane that covers the inner parts of your cat’s eyelids and covers the surface of the eye. Conjunctivitis has many possible causes including allergies, infections, injuries, and more.
Aside from the visible third eyelid, other more prominent symptoms include swelling, eye redness, continuous blinking, and crusty eye discharge. If your cat has watery eyes and sneezes, that’s another sign that your feline might be struggling with a conjunctival inflammation.
Many people wonder if they can treat conjunctivitis at home and ask, “Can you use human eye drops on cats?” However, you shouldn’t use anything on your feline’s eyes that’s not approved by a veterinarian. Anything that a vet does not prescribe can have negative effects, and you can make the situation worse.
Therefore, you should never try treating your cat at home. Instead, schedule a veterinary appointment. Depending on the cause, conjunctivitis is generally treated with eye drops or ointments prescribed by a professional.
3. Foreign Body
Foreign objects in your cat’s eyes can make the palpebra tertia appear, and it will stay there for a while. This can be any kind of object you can think of, including small particles such as dirt, dust, grass, stones, splinters, thorns, and other debris cats get in touch with during everyday life.
Since the third eyelid is a protective membrane, it will cover the eye to water it, try to remove the foreign body, and prevent it from getting into the eyeball. You might also see the actual foreign object inside the eye. Some of the other symptoms you should keep your eyes peeled for include:
- Constant blinking
- Eye redness or bleeding in the eyes
- Ocular discharge
- Pawing at the eyes
- Excessive eye-watering
Foreign bodies are a medical emergency; therefore, you should contact the vet immediately. If it’s a small particle, the cat might remove it with blinking and watering, but you should consult a professional just in case.
4. Ocular Trauma
A trauma to your feline’s eyes will make the nictitating membrane pop and protect the eyes. This is a common symptom due to blows to the head and direct injuries. Unfortunately, there are millions of ways your feline can be subjected to trauma, so creating a safe home and keeping your cats protected is the best prevention.
If there is serious trauma, you’ll notice various symptoms depending on the cause and location. Common pointers include excessive tearing, glassy eyes, bloodshot eyes, corneal ulcers, and scratches on the surface of the eyeball or around the face.
If you suspect that your feline went through any kind of trauma and you see the third lid showing, it’s time to call the vet. There can be many other underlying injuries that you can’t see and even serious injuries to the surrounding tissues. A professional will be able to give you the best next steps.
5. Upper Respiratory Infection
Did you know that cats are unfortunately prone to bacterial and viral infections? And one of the most common sites of infection is the upper respiratory tract. This is comprised of the nose, nasal cavity, throat, mouth, and voice box, thus upper respiratory infections have symptoms comparable to that of a human cold.
Therefore, if you spot your cat’s third eye showing and sneezing, one of the first causes I have in mind is an upper respiratory infection. Some of the other symptoms you can expect to see:
- Your cat coughing with tongue out
- Watery eyes and a runny nose
- Loss of appetite
- Frequent sneezing
- Pawing at the eyes
- Lethargy and general weakness
The most common forms of URI include the feline herpesvirus, Bordetella, feline calicivirus, and feline chlamydia. The course of treatment depends on the cause. Once you visit the vet’s office, they will determine whether it’s a virus or a bacteria and prescribe the proper medication. Bacterial infections are usually treated with antibiotics, whereas viral infections are usually fought off by themselves.
6. Parasitic Infections
Parasitic infections are also common in cats. Fleas and ticks live in your cat’s fur and are the most frequent parasitic infection you’ll come across. On the other hand, most worms reside inside the body. Some worms live inside the intestine and cause sickness and diarrhea, whereas heartworms live inside your cat’s heart.
Most people assume these pesky parasites only cause issues in the area they live, but they can have widespread effects throughout the body. For example, if you see your cat coughing but no hairball appears, you should suspect a heartworm infection. Likewise, infections caused by parasites can also attack the eyes and are more severe than you think.
If a parasite makes its way into the eye, it can cause permanent blindness, which is something you want to avoid at all costs. Eyeworms are particularly problematic. So, how will you recognize an eye parasitic infection?
Eyeworms cause all of the following symptoms:
- Frequent tearing
- The appearance of the third eyelid
- Itchiness and pawing at the eyes
- Inflammation and redness
- Secondary bacterial infections
The scariest thing is that you can actually see the worms moving around the eyes, so you’ll likely recognize this condition! If you don’t notice these signs right away, the eyeworms will continue to grow and deposit larvae in the eye. As such, you need to get your cat to the vet. The vet will remove the parasites with a tool.
7. Ocular Cancer & Tumors
Ocular cancer is rare in cats. However, if your cat’s third eyelid is showing and they’re lethargic, it is a possibility and so is worth mentioning. Ocular cancer can also mean your cat’s eyes are always dilated. Other signs of this serious medical condition include inflammation, eye discharge, improper iris shape, eye discoloration, and cloudy eyes.
Even though it’s not a common disease, ocular cancer spread quite quickly. Therefore, the sooner you have a diagnosis, the faster you can act. Contact your vet if you notice any of the above signs in combination – they might not have the condition but it is always best to be safe!
On the other hand, growths and cysts are formations that appear more frequently and can push the third eyelid. This causes it to appear even when the eyes are open. Tumors and formations require professional help and an urgent visit to the vet clinic.
8. Haw’s Syndrome
When the third eyelid protrusion or prolapse is also accompanied by intestinal issues such as diarrhea, vomiting, and intestinal parasites, this is a condition is called Haw’s Syndrome. Unfortunately, this is a common feline syndrome, and as a cat parent, you should know how to recognize it and deal with it.
In most cases, the syndrome lasts between four and six weeks and disappears after that. However, the causes of Haw’s syndrome are unknown. Although there are many guesses, no one knows for sure why this condition appears!
Therefore, it’s challenging to start a treatment. Vets will ensure that your cat gets the suitable therapy for accompanying symptoms such as intestinal parasites and diarrhea but will wait for at least two months to see if the eyelids will disappear. If not, make sure you head straight back to the vet.
9. Genetic Predisposition
Unfortunately, certain breeds are genetically predisposed to have issues with their third eyelids. For example, the third eyelids of beautiful Burmese cats often protrude more frequently and are visible when they’re not supposed to be.
Thankfully, these issues cause notable discomfort for the cats. However, cats with this genetic predisposition often have other eye issues to be aware of. For example, Burmese cats are prone to ruptures of the nictitating membranes. In addition, the third eyelid gland often becomes inflamed in Burmese cats, a condition better known as a cherry eye.
The only way you can treat a cherry eye or genetically-caused membrane issue is with surgery. Unfortunately, there are no treatment options to try at home, instead, you should immediately consult a professional.
10. Horner’s Syndrome
Horner’s syndrome is a condition that affects the nerves on the cat’s face that are responsible for the eyes and muscles. Once this neurological disorder appears, it is easily recognizable due to abnormal eye changes. For example, you will often see the third eyelid on only one eye, which leads to an asymmetric facial appearance.
The causes of this condition are still not completely familiar and, in most cases, the syndrome will disappear after some time. However, if you ever notice these symptoms, you should schedule a vet visit. Horner’s syndrome is often caused by another underlying illness or tumor that needs treatment.
One of the few times you shouldn’t be concerned about seeing the third eyelid is after sedation or anesthesia. Since your feline is deeply relaxed for a medical procedure, it will take some time to wake up and get back to normal. After the procedure, you might see the third eyelid, but it will slowly retract as the anesthesia wears off.
If the eyelids are still there the next day, you should contact the veterinarian. Moreover, if the cat keeps sneezing but seems fine, you should let the vet know. Although sneezing can occur a few days after your cat is sedated due to a surgical procedure, it can be a concerning sign. Sneezing can point to bacterial or viral infections that need treatment.
12. Dermoid Cyst
A dermoid cyst is something that a cat is born with. As the feline grows, so does the cyst, and it can be located in any area of its eyes. Since the cyst is not supposed to be there, it can very easily cause pressure on the surrounding tissues, including the third eyelids. If this happens, the nictitating membrane will appear.
In addition, there might be other symptoms such as eye discharge, frequent tearing, and pain, depending on the tissues that the cyst will affect. Thankfully, this cyst is quite rare among cats and appears early in the cat’s life. In some cases, the dermoid cyst can be treated with eye drops, but more severe cases will require surgery.
MY FINAL THOUGHTS
Have you noticed your cat’s third eyelid showing and lethargic behavior? Are you scared and worried because you have no idea why it happened and what you should do? There’s no need to panic since there’s not much you can do at home!
If you see a protruding membrane on your feline’s eye, the only thing to do is take your cat to the vet. Once the vet knows the reason, they’ll know how to treat the issue and help your furry friend feel better again. Most of the time, there is an eye condition that needs treatment. However, if your cat has just been sedated or is half asleep, give her a chance to wake up!