What Is Haw’s Syndrome in Cats?

Haw’s syndrome refers to the noticeable protrusion of a cat’s third eyelids across both eyes, with no underlying eye abnormalities. The third eyelid, also known as the nictitating membrane, typically remains tucked away in the corners of the eyes. However, when protruding, it indicates the presence of this rare condition. Haw’s syndrome primarily affects young adult cats, particularly those under two years of age, and is often associated with a recent episode of diarrhea. It is a self-limiting condition, which typically resolves on its own within a few weeks without requiring specific treatment.

Causes of Haw’s Syndrome

The exact cause of Haw’s syndrome remains uncertain. It is believed to involve a change in the nerves responsible for the third eyelid's movement, but the underlying factors are not fully understood. Haw’s syndrome is most commonly observed in cats that have experienced diarrhea, often caused by gastrointestinal conditions like parasites, viral infections, or dietary intolerances. While not all cases involve diarrhea, there appears to be a connection between gastrointestinal issues and the onset of the syndrome.

Signs and Symptoms of Haw’s Syndrome

The defining symptom of Haw’s syndrome is the visible protrusion of the third eyelid in both eyes, with no other eye abnormalities. This condition should not be confused with other causes of third eyelid visibility, such as tumors or Horner’s syndrome. Unlike Horner’s syndrome, which also causes a drooping eyelid and constricted pupil, Haw’s syndrome does not impact the cat's vision or cause pain. In some cases, cats may show additional signs of illness, such as lethargy or poor appetite, often linked to the underlying cause of diarrhea.

How Is Haw’s Syndrome Diagnosed?

Veterinarians typically diagnose Haw’s syndrome through a physical examination, where the characteristic protrusion of the third eyelids is evident. A thorough eye exam is conducted to rule out other causes of third eyelid protrusion, such as eye tumors or trauma. In rare instances, a phenylephrine test may be performed, where eye drops are applied to determine if the third eyelids return to their normal position within twenty minutes. If the cat is suffering from diarrhea, additional tests such as blood work and fecal analysis may be conducted to identify the underlying cause.

Treatment Options for Haw’s Syndrome

Most cases of Haw’s syndrome resolve without treatment, as it is a self-limiting condition. If the third eyelids obstruct the cat’s vision significantly, phenylephrine drops may be used temporarily to reposition the eyelids. However, this does not speed up recovery. Treatment is generally only necessary for underlying conditions, such as diarrhea. Cats with gastrointestinal issues may benefit from probiotics, a gastrointestinal support diet, or deworming if parasites are present. Recovery typically occurs within 6-8 weeks, with no further intervention required unless the condition persists.

Caring for a Cat with Haw’s Syndrome

While Haw’s syndrome is usually mild, it’s important to provide supportive care, especially if the cat is also dealing with diarrhea. Ensuring the cat stays hydrated and offering a gastrointestinal-specific diet will help manage symptoms and promote recovery. A bland, home-cooked diet such as chicken and rice can also be an option, but it lacks the essential nutrients found in specialized food. Additionally, a worming treatment may be advisable if intestinal parasites are suspected. Cats should be kept in a safe environment where they can rest and recover, especially if their vision is affected.

Preventing Haw’s Syndrome in Cats

Though the precise cause of Haw’s syndrome remains unclear, the condition is often linked to gastrointestinal disturbances. To prevent it, ensuring a balanced, consistent diet and avoiding abrupt dietary changes can help maintain gastrointestinal health. Regular deworming and staying current on vaccinations can also protect against infections that may trigger the condition. Since Haw’s syndrome is most commonly associated with gastrointestinal issues, maintaining overall gut health is crucial.