What causes cat third eyelid infections?

Understanding Cat Third Eyelid Infections: Causes and Insights

The third eyelid, or nictitating membrane, is an essential part of your cat's ocular health. This thin, light pink membrane sits at the inner corner of the eye and usually remains hidden unless there's a problem. When you notice your cat's third eyelid protruding or appearing more visible than usual, it's a sign that something is amiss.

What Is the Third Eyelid?

Cats—and many other animals—have a third eyelid that acts as a protective barrier for the eye. Its main jobs are:

• Shielding the eye from injury or foreign objects
• Producing tear film to keep the eye lubricated
• Acting as a barrier against irritants and pathogens

This membrane moves involuntarily, often when your cat is startled, sleepy, recovering from anesthesia, or experiencing discomfort. In healthy cats, you might only catch a glimpse of it when they’re drowsy or just waking up.

Why Does the Third Eyelid Become Visible?

A consistently visible third eyelid can indicate underlying issues. Here are some common reasons:

• Temporary causes: Sleepiness, anesthesia recovery (usually resolves quickly)
• Eye injuries or irritation: Corneal scratches, ulcers, foreign bodies in the eye
• Infections: Viral (like feline herpesvirus), bacterial (such as Chlamydophila felis), fungal agents—these often cause conjunctivitis or upper respiratory infections
• Haws syndrome: Symmetrical elevation of both third eyelids without primary eye disease; often linked to gastrointestinal upset and typically self-resolving
• Nerve damage or neurological conditions: Horner’s syndrome can cause an elevated third eyelid along with other symptoms like pupil constriction and drooping upper eyelids
• Cherry eye (prolapsed gland): Less common in cats but requires surgical attention if it occurs
• Systemic illness: Dehydration, fever, significant weight loss can all trigger third eyelid elevation
• Allergic reactions or chemical irritants
• Tumors or auto-immune conditions (rare)

The Role of Infections in Third Eyelid Problems

The most frequent infectious culprits behind third eyelid protrusion are:

• Viral infections: Feline herpesvirus (feline viral rhinotracheitis) and calicivirus commonly cause conjunctivitis and upper respiratory signs.
• Bacterial infections: Chlamydophila felis and Mycoplasma species can infect the conjunctiva.
• Fungal infections: Less common but possible in some regions.

These agents inflame the conjunctival membranes lining the inside of the eyelids and covering the white of the eye. This inflammation (conjunctivitis) leads to redness, swelling, discharge (which may be clear, yellow, or green), squinting, pawing at the face—and often exposure of the third eyelid.

Other Contributing Factors to Infection and Protrusion

• Irritants: Dust, chemicals, smoke—all can inflame sensitive tissues.
• Physical trauma: Scratches from play or fights with other animals may introduce bacteria directly into ocular tissues.
• Nail injuries: Cats sometimes scratch their own eyes while grooming if nails are too sharp.
• Poor hygiene/environmental factors: Crowded living conditions increase risk for contagious agents.
• Lack of routine veterinary care: Skipping regular checkups allows minor problems to escalate unnoticed.

Differentiating Third Eyelid Infection from Other Causes

A protruding third eyelid isn’t always due to infection. Sometimes gastrointestinal upset (Haws syndrome), neurological issues (like Horner’s syndrome), allergies, systemic illness—or even just sleepiness—can make it more visible. However, when infection is present you’ll usually see additional signs such as persistent discharge, redness around the eye rim, swelling of tissues near the inner corner of the eye, changes in vision or behavior (like rubbing at the face), and sometimes cloudiness over part of the cornea.

The Veterinary Diagnostic Approach

Your veterinarian will perform a thorough examination including:

1. An ophthalmoscopic exam to inspect internal structures of the eye for injury or inflammation.
2. Tear production tests to check for dry eye syndromes.
3. Cytology/culture swabs if infection is suspected—these help identify whether bacteria/viruses/fungi are responsible.
4. If GI disease is suspected: fecal testing for parasites or imaging studies may be recommended.
5. If systemic illness is possible: bloodwork and urinalysis help rule out broader health problems.

Treatment Strategies for Third Eyelid Infections in Cats

Treatment depends on what’s causing your cat’s symptoms:

• If it’s a simple viral/bacterial conjunctivitis: topical antibiotics/antivirals are prescribed; oral medications may be needed if there’s deeper infection.
• If there’s trauma: anti-inflammatory drops plus antibiotics prevent secondary infection while tissues heal.
• If cherry eye develops: surgical repositioning preserves tear function—removal is avoided due to risk of chronic dry eye later on.

Your vet will also advise supportive care such as gently cleaning away discharge with moistened cotton balls—but never use human medications on your cat’s eyes without professional direction!

Caring for Your Cat at Home & Prevention Tips

• Keen observation: Watch for any changes in your cat’s eyes—redness, swelling, discharge—or behavioral cues like pawing at their face.
• Sterile cleaning: Use only clean water/moistened cotton balls to wipe away gunk; avoid harsh chemicals near their face.
• Nail trimming: Keep claws short so accidental scratches don’t become infected wounds around delicate ocular tissue.

You can reduce risk by keeping your cat indoors (limiting exposure to infectious agents/trauma), maintaining a clean environment free from dust/irritants/chemicals, quarantining new pets before introduction to others in your home—and scheduling regular veterinary checkups for early detection of problems. If you spot persistent changes in your cat’s eyes—including ongoing visibility of their third eyelid—it’s time for prompt veterinary evaluation. Quick action helps prevent complications like vision loss down the road!