Why Does My Cat’s Third Eyelid Show? Causes of a Visible Third Eyelid
Felines have fabulous anatomical features that make them wonderfully mysterious—their whiskers, flexible spines, independently swiveling ears, and that curious little membrane that can suddenly appear across the eye.
If you’ve ever noticed a third eyelid, you’re not imagining it. Cats have a third eyelid, also called the nictitating membrane, located in the inner corner of each eye. Normally, it’s out of sight. When it becomes visible, however, it can be a sign that something deserves a closer look.
At Sunrise Boulevard Animal Hospital, we can help determine why your cat’s third eyelid is showing and whether treatment is needed.
What Is a Cat’s Third Eyelid?
Unlike the upper and lower eyelids, the third eyelid moves horizontally across the surface of the eye. It helps protect the eye and spread the tear film across its surface.
You may occasionally catch a glimpse of it when your cat is sleepy or just waking up.
But a visible third eyelid that remains noticeable while your cat is awake and alert can indicate an underlying problem.
In other words, seeing the third eyelid briefly during a particularly enthusiastic cat nap isn’t necessarily cause for alarm. Seeing it persistently is another story.
Causes of a Cat Visible Third Eyelid
There are several possible explanations for a cat third eyelid protruding, including:
- Eye irritation or inflammation
- Conjunctivitis
- Corneal injury or ulceration
- Foreign material in or around the eye
- Pain affecting the eye
- Dehydration or illness
- Gastrointestinal illness or other systemic disease
Look for Other Cat Eye Problems
A visible third eyelid on a cat is particularly worth investigating when it appears alongside other changes.
Watch for:
- Squinting or keeping an eye closed
- Excessive tearing
- Eye discharge
- Redness or swelling
- Cloudiness
- Pawing or rubbing at the eye
- Changes in appetite or energy
When to Call the Veterinarian
A cat with a persistently visible third eyelid should be evaluated, especially if the change appears suddenly or affects only one eye.
Cat eye problems can worsen quickly, and conditions such as corneal ulcers can be painful and require prompt treatment. If your cat is squinting, appears to be in pain, has swelling or discharge, or has suffered an eye injury, contact your veterinarian promptly.
Don’t try to force the eyelid open or put human eye drops into your cat’s eyes unless your veterinarian specifically recommends them.
Understanding Your Cat’s Mysterious Third Eyelid
The third eyelid is a perfectly normal part of feline anatomy. The mystery begins when it suddenly becomes much more visible than usual.
A persistent visible third eyelid is a clue that your feline friend needs some attention. Whether cat eye problems, discomfort, dehydration, or another illness is to blame, our team can examine your cat’s eyes and overall health to determine what’s behind the change and recommend appropriate care. Please contact us today at (916) 726-2334.