Cat Eye Infections and Conjunctivitis: Signs, Causes and Care

What causes eye infections in cats

The conjunctiva is the thin membrane that lines the eyelids and covers the white of the eye. When it becomes inflamed, the condition is called conjunctivitis or pink eye. The Merck Veterinary Manual describes feline herpesvirus-1 as a frequent cause and notes it is extremely widespread among cats. VCA Animal Hospitals adds feline calicivirus and bacteria such as Chlamydophila felis and Mycoplasma, and notes that a viral infection often opens the door to a second, bacterial one.

Not every red, weepy eye is an infection. VCA lists trapped debris, irritant chemicals, allergies, inward-rolling eyelids (entropion, common in Persians and Himalayans), dry eye, eyelid or eye tumors, corneal ulcers or injuries, glaucoma and inflammation inside the eye. Some of those are far more serious than a simple infection, which is one reason an eye with discharge should be examined rather than treated with whatever is in the cupboard.

Signs of an eye infection

Typical signs are extra tearing, discharge that may be clear at first and then cloudy, yellow or green, redness and swelling of the tissue around the eye, squinting, and sensitivity to light. VCA notes that the swelling can be severe enough to partly or completely cover the eye. A cat may rub its face on furniture or paw at the eye. One eye may be affected first, and the other often follows.

When the cause is a respiratory virus, eye signs usually come with sneezing, a runny nose, poor appetite or a fever. Merck notes that newborn kittens can develop heavy, thick eye discharge caused by the same bacteria and viruses that infect adults. Any kitten with eye discharge or swollen eyelids needs prompt veterinary attention.

When to call your vet today

VCA advises that any of these eye signs warrant an immediate vet exam, so call for a same-day or next-day appointment if your cat has a red, swollen or weepy eye, colored discharge, or is squinting. Eyes do not have much margin for error, and a problem that looks like simple conjunctivitis can be an ulcer on the surface of the eye or something stuck under the eyelid.

Call the same day for a kitten with eye discharge or swollen eyelids, a cat that has stopped eating, or signs that are not improving within a few days of starting treatment. Tell your vet about any previous eye problems, because herpesvirus can flare up again, especially during stress or illness.

When it's an emergency

Go to your vet or the nearest emergency vet immediately if your cat's eye has been injured, scratched or splashed with a chemical, if the eye looks cloudy or bluish, if you can see blood inside the eye, if the eye bulges or looks a different size from the other, or if your cat is holding the eye tightly shut and seems in pain. These can signal a deep ulcer, glaucoma or a serious injury that needs urgent treatment.

If a chemical has gone into the eye, call your vet or emergency clinic on the way for first-aid advice. Keep your cat from rubbing the eye during the trip, and bring the product packaging if a cleaning product or other chemical was involved.

What you can safely do at home

Do not use human eye drops, leftover pet eye medicine or ointment from a previous episode. VCA warns that a medicine that helped a previous bout of conjunctivitis may not help this time and may even be harmful. Only your vet can tell which one is safe after examining the eye.

What you can do safely is gently clean away discharge with a soft cotton pad or tissue moistened with clean, lukewarm water, using a fresh one for each eye and wiping away from the eye. Keep the cat indoors and away from dust or smoke, give it its own bowls and bedding if you have other cats, and wash your hands after touching its face, since infectious causes spread between cats.

What the vet will likely check

Merck notes that appearance alone is usually not enough for a diagnosis. Your vet will examine the eyes and eyelids, look for anything trapped, and may place a special stain on the eye to show any scratch or ulcer on its surface. Depending on the case, VCA lists tests of tear production and eye pressure, checks of the tear ducts, samples for the laboratory, and blood work for linked illnesses.

Treatment depends on the cause. It may include antibiotic eye drops or ointment, antiviral treatment for some herpesvirus cases, anti-inflammatory medicine for allergic conjunctivitis, and treatment of any underlying eyelid or tear problem. VCA reports most bacterial and viral cases resolve in 5 to 14 days, and the full course should be finished even if the eye looks better sooner.

Prevention

Keeping cats up to date on their core vaccines reduces how severe herpesvirus and calicivirus infections become. Isolate new cats for a week or two before they meet your others, keep sick cats separate, and keep cleaning products, sprays and smoke away from your cat's face. Good nutrition and low stress help cats that carry herpesvirus avoid flare-ups, according to VCA.

Non-infectious conjunctivitis tends to come back unless its cause is found and removed, so if your cat has repeated episodes, ask your vet about allergies, eyelid shape or dry eye. Regular checkups give your vet a chance to look at the eyes before a small problem becomes a big one.

This page is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your pet.