Haws syndrome in cats is a non-painful eye condition in which the third eyelid (the haw, nictitating membrane) becomes more visible across both eyes. Affected cats usually show no additional signs of eye disease. While cats of any age or breed can develop Haws syndrome, it’s most common in young adult cats under 2 years old and often accompanies gastrointestinal signs, such as diarrhoea.

Haws syndrome, also known as ‘bilateral prolapse of the third eyelid’, does not affect a cat’s vision, but the position of the third eyelid across the eye will partially obstruct their field of view. There’s no specific treatment for Haws syndrome itself, but the outlook is good as it generally resolves by itself once any underlying gastrointestinal issues are successfully treated. However, if your cat's eyes appear different or you have any concerns, it's always best to consult with a vet to rule out other problems.

What is Haws syndrome in cats?

Haws syndrome is a protrusion of the third eyelid. This is the transparent eyelid that sweeps across the eye when your cat blinks to moisten the eye and cover it for protection.

• This condition is not associated with eye diseases.

• The exact cause of Haws syndrome is unknown, also called ‘idiopathic’, but it may be caused by a temporary change in the nerve function of the third eyelid.

• Haws syndrome is most commonly seen following an episode of diarrhoea or gastrointestinal disease (such as having worms). However, the reason this happens is not fully understood.

Symptoms of Haws syndrome in cats

You may notice some or all of the following in your cat:

• Protrusion or increased visibility of the third eyelid in both eyes

• Diarrhoea a few days prior to the onset of eye signs

Are some cats more at risk of having Haws syndrome than others?

Although cats of any breed or age can develop Haws syndrome, it’s most common in younger adult cats with gastrointestinal illness.

Diagnosis of Haws syndrome in cats

If your cat has symptoms of Haw’s syndrome, your vet may recommend a few tests to help confirm the diagnosis and check for any underlying issues.

History & physical exam:

• The vet will check your cat’s overall condition, especially the eyes.

• Eye examination: A close-up eye check using a tool called an ophthalmoscope

• Extra tests to check for eye pressure, ulcers, or problems with tear production and nerves

• Phenylephrine drop test: Special eye drops may be used. If the third eyelids return to normal within 20 minutes, it supports the diagnosis of Haws. This effect is only temporary.

Looking for underlying causes:

• Faecal (stool) tests: To check for parasites or infections affecting your cat’s digestion.

• Blood tests: To rule out other illnesses, inflammation, or dehydration.

Haws syndrome usually improves on its own. Your vet may suggest simply monitoring your cat while treating any possible underlying causes.

Vet treatment of Haws syndrome in cats

No treatment is required for Haws syndrome itself, as signs will resolve on their own, usually within a few weeks. Your cat may need treatment for gastrointestinal disease if your vet suspects that this is the cause of their symptoms.

How to help your cat with Haws syndrome at home

• Monitor your cat: Look out for any new symptoms and reach out to a vet if your cat's diarrhoea does not resolve in 2 days.

• Maintain good home hygiene to reduce risk of transmission and reinfection if your cat has worms or diarrhoea.

• Clean litter trays regularly and dispose of faeces (poo).

• Wash all washable bedding and soft furnishings that your cat has been lying on.

Prevention of Haws syndrome in cats

Most cases of Haws syndrome have no known cause and cannot be prevented. Fortunately, the condition is not serious and often resolves on its own.

You can also minimise the risk by managing potential triggers and maintaining your cat's overall health. This includes addressing gastrointestinal issues, ensuring proper nutrition, and staying up-to-date on vaccinations and deworming.

• Worm adult cats at least 4 times per year. The choice of wormer depends on your cat’s age, lifestyle and other health concerns

• Feed your cat a balanced, high-quality diet and make any changes in diet very gradually.

• Schedule regular vet checks and keep up-to-date with vaccinations.

• Minimise stress factors and provide your cat with a stimulating and secure environment to reduce stress-related gastrointestinal upsets.

When to worry about your cat with Haws syndrome

Take your cat to the nearest vet practice if you notice the following symptoms:

• Squinting or rubbing of the eye

• Red eye

• Cloudiness of the eye

• Eye discharge

• Severe diarrhoea or diarrhoea that fails to resolve after 2 to 3 days

• Poor appetite or lethargy

Joii can help with:

• Recognising the symptoms of Haws

• Advising on treatment for diarrhoea

• Discussing worm treatment

• Monitoring recovery