Moderate severity

Haws Syndrome (Third Eyelid Protrusion)

A condition in which both third eyelids — the extra membranes at the inner corner of each eye — become visible and slide partly across the eyes, classically alongside a bout of diarrhoea.

⚠️ Common symptoms

The pale third eyelids visible across the inner corner of both eyesA sleepy or 'half-covered' look to the eyes, though vision is usually normalOften accompanied by diarrhoea or a recent tummy upsetOtherwise bright, alert and eating in many casesBoth eyes affected together rather than just one

Haws syndrome is one of those conditions that looks alarming but is usually far less serious than it first appears. The 'haws' are the third eyelids — protective membranes tucked into the inner corner of each eye that normally sweep across only briefly. In Haws syndrome they sit partly drawn across both eyes at rest, giving a cat a distinctive drowsy, half-masked expression even though it can see perfectly well.

The characteristic clue is the company it keeps: Haws syndrome very often turns up alongside a bout of diarrhoea or another digestive upset. The connection is thought to run through the nervous system, with a temporary disturbance to the nerves that keep the third eyelids retracted. This is why the condition affects both eyes together — a helpful feature that distinguishes it from problems affecting a single eye.

The reassuring part is that Haws syndrome typically fades by itself once any underlying tummy trouble settles, often over a couple of weeks, and needs no direct treatment of the eyes. The important caveat is that a visible third eyelid can also signal pain, injury or more serious nerve conditions, so it is always worth a vet confirming that simple Haws syndrome is really what is going on rather than assuming it.

🔍 Causes

The exact mechanism is not fully understood, but Haws syndrome is linked to disturbances of the nervous supply to the third eyelid, frequently in association with gastrointestinal upset such as diarrhoea or a viral or parasitic gut infection. It is thought to involve the sympathetic nerves that normally hold the third eyelid retracted, which is why both eyes are affected at once.

🛡 Prevention

There is no specific way to prevent Haws syndrome, but supporting good gut health helps — routine parasite control, a stable diet, and prompt attention to diarrhoea. Keeping vaccinations up to date and reducing exposure to gut infections lowers the chance of the digestive upsets it is associated with.

💊 Treatment

Haws syndrome itself usually needs no direct treatment and resolves on its own over days to a few weeks. Care focuses on any underlying gut upset — keeping the cat hydrated, feeding a bland easily digested diet if advised, and treating intestinal parasites or infection where your vet finds them. Because a protruding third eyelid can have other, more serious causes, a vet should confirm the diagnosis before it is put down to simple Haws syndrome.

When to see a vet: See your vet if your cat's third eyelids become visible, both to confirm the cause and to address any accompanying diarrhoea. Seek prompt attention if only one eye is affected, if the eye is painful, red, or the vision seems impaired, or if there are other neurological signs such as a drooping eyelid or sunken eye, as these point away from simple Haws syndrome toward conditions needing specific treatment.

⚕️ Medical disclaimer

  • This information is educational only and is not a substitute for veterinary advice.
  • Symptoms overlap between conditions — only a vet can diagnose accurately.
  • Never withhold treatment or self-medicate based on information found online.
  • When in doubt, call your vet. Early intervention almost always leads to better outcomes.

← Back to Health & Ailments