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Cat conjunctivitis
Conjunctivitis is the inflammation of the thin pink membrane that lines the inside of the eyelids and the white of the eye. This is the most common reason for eye consultation in cats. It results in a red, watery eye, often held half closed...
What is it?
Conjunctivitis is the inflammation of the thin pink membrane that lines the inside of the eyelids and the white of the eye. This is the most common reason for eye consultation in cats.
It results in a red, watery eye, often held half closed. Only one eye may be affected at first, then the second.
In cats, the cause is very often infectious, unlike dogs where allergies and irritations dominate. This is why feline conjunctivitis always deserves veterinary advice rather than improvised treatment.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Redness of the whites of the eye and the inside of the eyelids.
Clear tearing at first, which may become thick and yellowish.
Swollen eyelids, half-closed or completely closed eye.
Repeated blinking, cat rubbing its eye with its paw or against furniture.
The third eyelid, this whitish veil located at the inner corner of the eye, can rise and hide part of the globe.
Sneezing, runny nose and loss of appetite when conjunctivitis is part of a coryza picture.
Discomfort with light: the cat seeks darkness.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Viral infections come first, in particular feline herpesvirus, responsible for a large part of conjunctivitis in cats and capable of recurring throughout life.
Bacteria such as chlamydia and mycoplasma cause often prolonged conjunctivitis, common in kittens and groups of cats.
A local cause must always be sought: foreign body, misdirected hair or eyelash, dust, irritant product, draft from a car journey.
Trauma, particularly a scratch during a fight, can trigger inflammation and be accompanied by damage to the cornea.
More rarely, conjunctivitis is the visible sign of a general illness or a defect in tear production.
Kittens and young cats, whose immunity is still immature.
Group living: shelters, breeders, colonies, homes with several cats.
Cats not vaccinated or whose boosters are not up to date.
Recent stress: moving, adoption, new arrival at home, hospitalization.
Access to the outside, with fights and dust projections.
Diseases that weaken the defenses, such as FIV and feline leukosis.
Transmission
Infectious forms are transmitted from one cat to another through secretions from the eyes and nose, during direct contact, mutual grooming, sneezing, but also through bowls, beds and hands handling several cats.
A cat carrying the herpesvirus can remain contagious intermittently, often during an episode of stress, even if it appears healthy.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian examines both eyes, inverts the eyelids for a foreign body, and assesses for pain.
A test with fluorescein, an orange dye placed on the eye, is almost always carried out: it reveals a possible corneal wound, which completely changes the course of action to take.
Tear production can be measured with a test strip if dry eye is suspected.
In the event of persistent or recurring conjunctivitis, samples can be used to test for herpesvirus, chlamydia or mycoplasma.
A general examination completes the consultation, the eye may be the visible part of a respiratory or general illness.
Treatment
Treatment depends on the cause: there is no universal eye drop for all red eyes.
Bacterial forms require a local antibiotic prescribed by the veterinarian, sometimes supplemented by general treatment.
Forms linked to herpesvirus may justify an antiviral, locally or orally, and support for eye comfort.
Gentle saline washes help remove secretions before each application, with a different compress for each eye.
Eye drops containing a corticosteroid should never be used without prior examination: applied to an eye with an ulcer, it can aggravate the lesion to the point of perforation.
Never apply eye drops prescribed for another animal, for another condition or during a previous episode to your cat's eye: an opened bottle is also a source of contamination.
A collar is often necessary to prevent the cat from scratching its eye.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Vaccination against the main coryza viruses limits the frequency and severity of episodes.
Isolate a cat that shows ocular or respiratory signs until it has been seen by a veterinarian.
Wash your hands between each cat, clean the bowls and beds, avoid sharing equipment in a community.
Reduce the sources of stress, which encourage the awakening of the herpesvirus: high rest areas, sufficient number of litter boxes, gradual changes.
Avoid cleaning products sprayed near the cat and direct air currents on the head.
Vaccination
The so-called coryza vaccine, administered as a primary vaccination in kittens then maintained by boosters, targets in particular herpesvirus and calicivirus, two major causes of feline conjunctivitis.
It does not make the cat completely immune to infection, but it significantly reduces the episodes and their complications.
The rhythm of the reminders is adapted by the veterinarian to the cat's lifestyle, a cat going out or living in a group being more exposed than a cat alone in an apartment.
Possible complications
Extension of the inflammation to the cornea, with risk of ulcer.
Adhesions between the conjunctiva and the cornea after severe inflammation, especially in kittens.
Evolution towards a chronic form which recurs with each decline in form.
Long-term damage to the tear ducts, with a permanently running eye.
When to see a veterinarian
The eye is red, closed or painful: consult, eye inflammation is not expected.
The cat rubs its eye repeatedly or refuses to let anyone approach its head.
The discharge becomes thick, yellow or greenish.
The surface of the eye appears cloudy, bluish or marked with a hollow.
The cat no longer eats, sneezes and becomes weak.
The signs persist beyond twenty-four to forty-eight hours or worsen despite treatment.
A kitten has a stuck or swollen eye even before the eyelids open: it is an emergency.
Prognosis
The vast majority of conjunctivitis heals well when treated early and with the right product.
Forms linked to herpesvirus can recur throughout the cat's life, without compromising its comfort if the episodes are managed.
The prognosis deteriorates especially when a corneal ulcer has gone unnoticed or a corticosteroid has been wrongly applied.
Frequently asked questions
Can I clean my cat's eye while waiting for the appointment?
Yes, with sterile physiological serum and a clean compress, one compress per eye, from the inner corner outwards. It is a comfort treatment, it does not replace the examination: only the veterinarian can check that the cornea is intact.
I have eye drops left over from a previous conjunctivitis, can I use them?
No. The product may not correspond to the current cause, and if it contains a corticosteroid it may aggravate an ulcer to the point of endangering the eye. An already opened bottle is also contaminated.
Is my other cat at risk of being infected?
Yes, if the cause is infectious. Separate cats, use separate bowls and wash your hands between each animal until diagnosis.
My cat's conjunctivitis returns several times a year, is this normal?
This is very suggestive of an established herpesvirus, which wakes up during periods of stress. The veterinarian can suggest a basic strategy and measures to limit triggers.
References
AAFP — American Association of Feline Practitioners
Content reviewed by the TunisieVet editorial team · Updated 09 August 2026
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