Noticing your cat’s third eyelid showing can be startling—especially if it’s never happened before. This inner eyelid, also called the nictitating membrane, usually stays hidden. When it’s visible, it could mean your cat is tired, ill, or something more serious is going on.
In this in-depth guide, we’ll explore what the third eyelid is, why it might be showing, when it’s normal (and when it’s not), and what you should do about it. If your cat’s condition is also leading to spraying or behavior changes, we’ll introduce a proven method to restore peace at home.
What Is the Cat’s Third Eyelid?
The third eyelid is a protective membrane located at the inner corner of your cat’s eye. It acts like a built-in shield to protect the eye from dust, debris, and injury. In healthy cats, it stays tucked away and is rarely seen.
You might catch a glimpse when your cat is drowsy or just waking up—but if it stays visible for more than a few minutes or becomes more prominent over time, it’s likely a sign of a problem.
Why Is My Cat’s Third Eyelid Showing?
A visible third eyelid often signals illness, discomfort, or stress in cats. It can appear in one eye or both, and the visibility may vary depending on your cat’s position or activity. Below are the most common causes:
1. Illness or Infection
The most frequent reason for a cat’s third eyelid to show is general illness. Viral or bacterial infections—especially upper respiratory infections—can lead to lethargy, fever, or eye irritation, triggering the membrane to appear.
2. Dehydration or Fatigue
When cats are dehydrated, weak, or extremely tired, their third eyelid may become more visible. You’ll often see this after anesthesia, illness, or severe diarrhea and vomiting.
3. Eye Injury or Irritation
If your cat has scratched their eye, developed conjunctivitis (pink eye), or suffered trauma, the third eyelid may extend as a protective response.
4. Pain or Nausea
Cats in pain—especially with digestive discomfort—often show their third eyelid. You might also notice decreased appetite, hiding, or restlessness. This is common with gastrointestinal issues, parasites, or poisoning.
5. Haws Syndrome
This condition causes both third eyelids to protrude symmetrically, usually in young cats. It’s believed to be linked to gastrointestinal infections, such as worms or viral illness. Haws Syndrome typically resolves within a few weeks with treatment of the underlying cause.
6. Cherry Eye (Rare in Cats)
Unlike dogs, cherry eye is rare in cats. However, in some cases, the gland in the third eyelid can prolapse, causing a red, swollen bulge. This requires surgical correction.
7. Neurological Issues
Injury to the head, spine, or certain nerves can cause abnormal eyelid movement. In these cases, your cat may show additional signs like wobbling, head tilting, or abnormal pupil dilation.
If your cat’s visible third eyelid is accompanied by changes in behavior—like spraying, hiding, or excessive meowing—stress may be playing a role.
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Is It Ever Normal to See the Third Eyelid?
Sometimes, yes—but only briefly. A quick appearance of the third eyelid during sleep, anesthesia recovery, or extreme relaxation can be normal. It usually slides back when your cat becomes fully alert again.
If the membrane remains visible for hours—or worsens over days—it’s no longer normal and should be investigated.
How to Tell If It’s Serious
Watch for these warning signs that your cat’s third eyelid issue is connected to a deeper health problem:
- Third eyelid is visible for more than 24 hours
- Both third eyelids are up, especially with diarrhea (possible Haws Syndrome)
- Eye discharge (yellow, green, or thick)
- Squinting, pawing at eyes, or blinking excessively
- Lethargy, hiding, vomiting, or loss of appetite
- Behavior changes—spraying, meowing, aggression, or withdrawal
Any of the above signs mean it’s time to call your vet.
What Your Vet May Do
Your vet will perform a full exam and likely focus on the eyes, gut, and neurological function. Common diagnostics include:
- Fluorescein staining (checks for corneal damage)
- Eye pressure testing (rules out glaucoma)
- Blood work to check for infection or organ dysfunction
- Stool tests for parasites (especially in Haws Syndrome)
Treatment depends on the cause and may include:
- Eye drops or ointments (antibiotic or anti-inflammatory)
- Hydration and anti-nausea medication
- Deworming treatments
- Supportive care for illness or pain management
Can You Treat a Visible Third Eyelid at Home?
No, not directly. The third eyelid is a symptom—not the problem itself. While you can offer supportive care, only a vet can determine the cause and guide treatment.
That said, here are a few safe, supportive steps you can take:
- Keep your cat indoors and resting
- Provide clean water and tempting, easy-to-digest food
- Monitor for worsening symptoms or new behaviors
- Minimize stress with soft bedding and quiet space
Many cats become anxious or territorial when sick—leading to spraying or unusual behavior. Don’t ignore the emotional side of healing.
Try Cat Spray No More to address stress-based spraying and restore harmony—especially during recovery periods.
Behavior Changes Linked to Illness
When a cat doesn’t feel well—especially if they’re in pain or discomfort—they often act out in ways that are hard to interpret:
- Marking territory or spraying indoors
- Hiding, avoiding affection, or seeming depressed
- Over-grooming or neglecting grooming entirely
- Vocalizing more than usual or acting restless
These behavioral symptoms are just as important to monitor as physical ones. Your cat may not be trying to misbehave—they may simply be stressed, scared, or confused by what their body is going through.
When to Call the Vet Immediately
Do not wait to get help if you notice any of the following:
- Persistent third eyelid visibility in one or both eyes
- Eye swelling, bleeding, or trauma
- Seizures, stumbling, or other neurological signs
- Complete loss of appetite for 24+ hours
- Spraying, aggression, or sudden fear responses
Prompt care not only protects your cat’s vision but could also catch serious conditions like dehydration, parasites, or internal illness before they worsen.
How to Prevent Third Eyelid Issues
While you can’t prevent every illness, you can take steps to reduce the likelihood of eye-related and systemic health problems:
- Keep vaccines up to date—especially for respiratory viruses
- Use monthly parasite prevention (especially deworming)
- Avoid exposure to aggressive cats or wildlife
- Monitor behavior and appearance daily
- Maintain a low-stress, enriched environment
Final Thoughts
Your cat’s third eyelid showing is never something to ignore. While it might be as simple as sleepiness or dehydration, it can also be a red flag for illness, injury, or stress. The sooner you take action, the better the outcome—especially when paired with other symptoms or behavior changes.
And remember—healing goes beyond the physical. If your cat is also spraying, acting out, or struggling with territory insecurity during illness, their emotional needs are just as important as medical ones.
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