Most pet parents probably don’t know that their pet has THREE eyelids on each eye: 2 you can see easily, and 1 that sits in the inner corner of the eye. This third eyelid is usually tucked away, so when cat parents notice it sticking out, they may wonder why. If you notice this, you should give your veterinarian a call, but if they diagnose Haws syndrome in cats, you shouldn’t be too worried.

What Is Haws Syndrome?

Haws syndrome is specific to cats – dogs do not get this. It is a rare condition that tends to affect cats less than 2 years old. It is when the third eyelids stick up over part of a cat’s eyes. 

This condition is not painful and does not affect the eye, although your cat’s vision will be slightly decreased because the eyelid physically covers part of the eye.

A lack of response in sympathetic nerves – the nervous system responsible for the “fight or flight” response – allows the eyelids to stay up when they should go down. It is unknown why this occurs.

What Causes Haws Syndrome in Cats?

Haws syndrome has no known cause. The syndrome itself is not contagious. No breed appears to be more heavily affected over others.

However, many cases are associated with a recent bout of diarrhea, most of which resolve in a matter of a few days. One study found a specific gastrointestinal (i.e. stomach and/or intestines) virus called torovirus in many cats with Haws syndrome, but other studies have not had this same result. A case was reported of a cat with Giardia infection and Haws syndrome. Still, many other cats have not had diarrhea.

Haws Syndrome Cat Symptoms

Haws syndrome has only one symptom – the third eyelids are constantly raised in both eyes. 

Haws syndrome does not cause death. The eyes themselves are otherwise normal – normal vision, no inflammation or infection, and no swelling around the eyes that could cause the third eyelids to raise. 

While diarrhea is sometimes noted around the time that Haws syndrome occurs, diarrhea is not a symptom of Haws syndrome.

Diagnosing Cats with Haws Syndrome

Diagnosis is based on a physical examination by a veterinarian. Your veterinarian will need to perform a thorough ophthalmic (eye) examination to look for a potential cause of the raised eyelids. Additionally, your veterinarian may focus on the nervous system. 

Fecal testing may be performed to look for a cause of any diarrhea that may have occurred around the time of diagnosis.

An eye drop that stimulates the sympathetic nerves such as phenylephrine can be applied to the eyes once to confirm diagnosis. Within 20 minutes of applying this medication, the third eyelids will return to normal position. If this medication is not used, Haws syndrome would be diagnosed based on a physical examination, ruling out any other diseases that could have caused the raised third eyelids.

How to Treat Haws Syndrome in Cats

There is no treatment for Haws syndrome, but it often goes away on its own. Studies about Haws syndrome in cats are few and far between. In one study, 62 percent of cats’ raised eyelids resolved within 4 weeks. In another study, the average time till the syndrome resolved was 47 days.

Eye medication such as phenylephrine can be used to replace the eyelids in their original positions, but because cats do not have any discomfort or significant decrease of vision with this condition, this kind of medication would often be unnecessary.

How to Prevent Haws Syndrome in Cats

There is no way to prevent Haws syndrome. Until the syndrome is better understood, it is unlikely prevention will be possible. 

Although diarrhea is not necessarily a cause of Haws syndrome, preventing diarrhea may decrease the chance of Haws in the future. One way to do this is  to prevent your kitty from getting into the trash or eating food items other than cat food. For cats younger than 2 years old, providing your cat with regular deworming will help decrease parasites and thus lower the chances of diarrhea.