MCV FAQ - Why Does My Cat Have Runny Eyes?

It’s quite common for cat owners to notice their pet has watery or runny eyes. Sometimes it’s just a small amount of discharge that clears on its own, but in other cases it can be a sign of something that needs veterinary attention. Understanding why cats develop runny eyes can help you decide when to seek help.

Normal Tear Production

Cats, like people, produce tears to keep the surface of the eye healthy. Tears help wash away dust and protect the eye from infection. If the tear ducts become blocked, tears may overflow and cause constant watery eyes even though the eye itself is normal.

An illustration of the normal tear production and drainage of the eye. Blocked tear ducts are a common cause of watery eyes in cats.

Medical Causes of Runny Eyes

There are many reasons a cat may develop watery eyes. Some of the more common ones include:

• Allergies or irritation of the conjunctiva – things like dust, pollen, cigarette smoke, or household sprays can irritate the eyes.

• Eye infections – viruses such as feline herpesvirus or calicivirus, and bacteria like Chlamydia felis or Mycoplasma can cause conjunctivitis (inflammation of the eye surface). These usually produce watery or mucky discharge, often with redness.

• Eye structure – some breeds, especially Persians and other flat-faced cats, have shallow eye sockets and narrow tear drainage pathways, making them prone to tearing.

• Corneal problems – scratches, ulcers, or foreign bodies in the eye cause pain and watering. Cats with these issues often blink or keep the eye shut.

• Entropion – where the eyelids roll inward, rubbing hairs against the cornea.

• Glaucoma or uveitis – more serious internal eye diseases that can cause discharge along with cloudiness, color change, or pain.

  
  
  
  

There are numerous causes of watery eyes in cats. A veterinary examination can often determine the cause.

When to Make an Appointment

Mild, occasional watery eyes may not be a concern, especially if your cat is otherwise well. But you should have your cat checked promptly if you notice:

• Redness, swelling, or persistent discharge

• Thick yellow or green mucus

• Squinting, pawing at the eye, or keeping the eye closed

• Cloudiness, a change in pupil size, or loss of vision

• Discharge affecting only one eye (this can signal injury or a localised problem)

  
  

Most cats are OK with undergoing a close up eye exam in the clinic.

Treatment depends on the cause. For example, blocked tear ducts might be flushed, infections may need eye drops or tablets, and eyelid problems sometimes require surgery. Viral infections can flare up again and may need long-term management.

Runny eyes in cats can be as simple as a blocked tear duct or as serious as an eye ulcer or glaucoma. Because it’s not always easy to tell at home, and because untreated eye problems can lead to pain or vision loss, it’s best to seek veterinary advice if your cat has persistent, painful, or worsening eye discharge.