Haws Syndrome in Cats 👁️🐱

By Dr Duncan Houston, BVSc

Noticed your cat’s third eyelid suddenly visible in both eyes? This unusual but benign condition is called Haws Syndrome. Though alarming in appearance, it’s typically painless and temporary. In this expert 2025 guide, Dr Duncan Houston breaks down the symptoms, causes, diagnosis, and care for Haws Syndrome in cats. 🩺

🔍 What Is Haws Syndrome?

Haws Syndrome refers to the bilateral elevation of the third eyelid (nictitating membrane) in cats. This translucent membrane normally remains hidden unless it’s actively protecting or lubricating the eye. In Haws, both third eyelids are prolapsed or elevated even though there is no eye pain, trauma, or infection. 👁️

📖 Also known as:

• 👀 Bilateral third eyelid protrusion
• 👁️ Bilateral prolapse of the nictitating membrane

🧠 What Causes Haws Syndrome?

The exact cause is unknown, but Haws is frequently linked to gastrointestinal (GI) inflammation or infections. Diarrhea often precedes the eye changes. One theory is that nerves controlling the third eyelid are affected by systemic inflammation, especially from the gut. 🔬

Though reported mainly in cats, this syndrome has not been documented in dogs.

📋 Signs to Watch For

• 👁️ Visible third eyelids in both eyes—often whitish or opaque
• 😼 No eye pain or squinting
• 💩 Diarrhea or recent digestive upset
• 👓 Possible visual obstruction if third eyelids are covering part of the eye

Note: Vision remains normal, but may be functionally impaired if the third eyelid blocks the visual field. 🧠

🩺 Diagnosis

Your veterinarian will perform a thorough physical and ophthalmic exam to rule out other causes of third eyelid elevation, such as:

• 🔍 Trauma
• 🔬 Ocular infections
• 🧠 Horner’s syndrome
• 💧 Dehydration

Phenylephrine Challenge Test

A special eye drop test may be used to confirm Haws Syndrome:

• 💧 Phenylephrine drops are applied to the eye
• ⏱️ If the third eyelid retracts within 20 minutes → Haws is likely

💊 Treatment & Recovery

No specific treatment is usually required for the eye symptoms—Haws Syndrome is typically self-limiting. However, treating any associated GI symptoms (like diarrhea) is important for resolution. 🩹

Recovery Timeline

• ⏳ Average recovery: 2 to 6 weeks
• 🧾 Some cats may take longer—up to 47 days or more
• 📈 If the third eyelids remain elevated beyond 4 weeks, re-evaluation is advised

🔬 Prognosis

The long-term outlook is excellent. Most cats recover without complications. Recurrence is rare, especially if GI issues are promptly addressed. 🐾

🧼 Preventive Care

• 🥘 Ensure high-quality, digestible nutrition
• 🚰 Monitor for dehydration or loose stools
• 🧽 Keep eyes clean with saline if discharge occurs
• 🏥 Promptly treat any digestive issues or parasitic infections

📱 Ask A Vet App Support

Concerned your cat’s third eyelid looks abnormal? The Ask A Vet app provides peace of mind:

• 📷 Upload eye photos for review
• 💬 Real-time chats with licensed vets
• 🧾 Get treatment suggestions for accompanying GI symptoms
• 📈 Monitor recovery progress and get reminders

🏁 Final Takeaway

Haws Syndrome may look strange, but it’s usually nothing to fear. With gentle support and monitoring, most cats recover fully—especially when any underlying GI issues are addressed. Partner with your veterinarian and use tools like the Ask A Vet app to track your cat’s progress and get expert guidance every step of the way. 👁️🐱🩺