Last updated: March 26, 2026

Conjunctivitis in Cats: Pink Eye Causes & Treatment

Conjunctivitis in cats is the single most common eye condition veterinarians diagnose in feline patients. If you have noticed your cat squinting, pawing at their face, or developing a discharge that crusts around the eye, there is a good chance conjunctivitis is involved. While the condition ranges from mild irritation to a sign of something more serious, understanding what you are looking at and when to seek veterinary help makes all the difference in your cat’s comfort and long-term eye health.

The conjunctiva is a thin, transparent mucous membrane that lines the inner surfaces of the eyelids and covers the white part of the eye. When this membrane becomes inflamed, the result is conjunctivitis — commonly called pink eye. In cats, this inflammation is rarely an isolated problem. It almost always points to an underlying cause that needs to be identified and addressed for treatment to be effective.

What Is Conjunctivitis in Cats?

Conjunctivitis refers specifically to inflammation of the conjunctival membrane. In healthy cats, this membrane is pale pink and barely noticeable. When inflamed, it becomes red, swollen, and often produces abnormal discharge. The condition can affect one eye (unilateral) or both eyes (bilateral), and this distinction can help point toward the underlying cause.

Feline conjunctivitis is categorized broadly into infectious and non-infectious forms. Infectious conjunctivitis is by far the more common category in cats and is usually caused by viruses or bacteria. Non-infectious causes include allergies, irritants, foreign bodies, and anatomical abnormalities. Unlike in humans, where viral conjunctivitis is typically self-limiting and mild, feline conjunctivitis often requires veterinary treatment because the underlying causes tend to be more persistent.

The condition can be acute, appearing suddenly and resolving with treatment, or chronic, persisting for weeks or recurring periodically. Chronic or recurrent conjunctivitis is particularly common in cats and is often linked to feline herpesvirus, which establishes lifelong latent infections that can reactivate during periods of stress or immune suppression.

Causes of Conjunctivitis in Cats

Feline Herpesvirus-1 (FHV-1). This is the single most common cause of conjunctivitis in cats worldwide. FHV-1 is an upper respiratory virus that the vast majority of cats are exposed to at some point in their lives, particularly those that have spent time in shelters or multi-cat environments. After initial infection, the virus becomes latent in nerve tissue and can reactivate periodically throughout the cat’s life, causing recurrent episodes of conjunctivitis and upper respiratory symptoms. Stress, illness, surgery, or corticosteroid use can trigger reactivation. FHV-1 conjunctivitis is often accompanied by sneezing, nasal discharge, and fever, especially during the initial infection.

Chlamydophila felis. This obligate intracellular bacterium is the second most common infectious cause of feline conjunctivitis. Chlamydophila typically produces a unilateral conjunctivitis that becomes bilateral within days. The discharge tends to be more purulent (thick and yellowish-green) compared to the watery discharge of early viral conjunctivitis. Kittens and young cats in multi-cat households are most commonly affected. Unlike herpesvirus, Chlamydophila responds well to appropriate antibiotic therapy and does not establish lifelong latent infections.

Mycoplasma species. These bacteria can cause conjunctivitis alone or as co-infections with herpesvirus or Chlamydophila. Mycoplasma conjunctivitis tends to produce a characteristic pseudomembrane — a film of inflammatory debris on the conjunctival surface — that can be seen during examination.

Feline Calicivirus (FCV). While calicivirus primarily causes oral ulcers and upper respiratory symptoms, it can occasionally contribute to conjunctivitis, particularly in kittens experiencing their first infection.

Non-infectious causes. Allergies to environmental triggers like pollen, dust, or household chemicals can cause conjunctivitis, though allergic conjunctivitis is less common in cats than in dogs or humans. Foreign bodies — grass seeds, dust, or litter particles — can irritate the conjunctiva. Entropion, a condition where the eyelid rolls inward so that eyelashes rub against the eye surface, causes mechanical irritation and secondary conjunctivitis. Certain breeds with flat faces and prominent eyes, such as Persians and Himalayans, are anatomically predisposed to chronic eye issues.

Symptoms of Conjunctivitis in Cats

The symptoms of conjunctivitis in cats range from subtle early signs to obvious, uncomfortable inflammation. Being attentive to the early indicators allows you to seek treatment before the condition worsens.

Eye discharge is usually the first thing owners notice. The type of discharge provides clues about the cause. Clear, watery discharge (serous) is typical of viral infections in the early stages or allergic reactions. Thick, yellowish-green discharge (mucopurulent) suggests bacterial involvement, either as a primary cause or secondary infection. Crusty buildup around the eye, particularly after sleep, indicates ongoing discharge production.

Redness and swelling of the conjunctival tissue is the defining sign. The inner eyelids appear redder than normal, and the tissue may be visibly puffy. In severe cases, the conjunctiva can become so swollen (chemosis) that it bulges outward from between the eyelids. The third eyelid — a translucent membrane in the inner corner of the eye — may become elevated and partially cover the eye, which is a reliable sign that the eye is irritated or painful.

Squinting and blinking (blepharospasm) indicate pain or discomfort. A cat with conjunctivitis often holds the affected eye partially closed. Frequent blinking, rubbing at the eye with a paw, or rubbing the face against furniture are all signs of ocular discomfort.

Behavioral changes can include decreased appetite, reduced playfulness, hiding, or increased sleeping. Cats in pain often withdraw rather than showing obvious distress. If your normally social cat becomes reclusive while showing any eye changes, take it seriously.

When conjunctivitis accompanies upper respiratory infection, you may also notice sneezing, nasal discharge, congestion, fever, and lethargy. Kittens are particularly vulnerable to severe upper respiratory infections and can deteriorate quickly, so prompt veterinary attention is important for young cats showing these signs.

Diagnosis of Feline Conjunctivitis

Veterinary diagnosis of conjunctivitis involves a thorough eye examination and, in many cases, specific diagnostic tests to identify the underlying cause.

Ophthalmic examination. The veterinarian will examine the eye using an ophthalmoscope and magnification, assessing the degree of conjunctival inflammation, the type and amount of discharge, the condition of the cornea, and the overall structure of the eye. They will check for foreign bodies, eyelid abnormalities, and signs of deeper eye involvement.

Fluorescein stain test. A drop of fluorescent green dye is applied to the eye surface. If the cornea is damaged (corneal ulcer), the dye adheres to the damaged area and glows green under blue light. Corneal ulcers can develop secondary to conjunctivitis, particularly with herpesvirus infections, and they require additional treatment to prevent serious complications including vision loss.

Schirmer tear test. This measures tear production by placing a small strip of absorbent paper inside the lower eyelid for one minute. Low tear production (keratoconjunctivitis sicca or dry eye) can cause or worsen conjunctivitis.

Conjunctival swabs and PCR testing. For recurrent or severe cases, the veterinarian may collect a swab from the conjunctival surface and submit it for polymerase chain reaction (PCR) testing. PCR can identify specific pathogens including FHV-1, Chlamydophila felis, and Mycoplasma. Knowing the exact pathogen guides treatment decisions and helps predict the likely course of the disease.

Cytology. Examining cells from the conjunctival surface under a microscope can reveal patterns that point toward viral, bacterial, or allergic causes. Eosinophils suggest an allergic component, while inclusion bodies within cells can indicate Chlamydophila infection.

Treatment of Conjunctivitis in Cats

Treatment depends on the underlying cause, but most cats with conjunctivitis require some combination of topical eye medications and supportive care.

Antiviral therapy. For herpesvirus-associated conjunctivitis, antiviral eye drops or ointments are the mainstay of treatment. Famciclovir given orally has become the most commonly prescribed systemic antiviral for feline herpesvirus and is well-tolerated. Topical options include cidofovir eye drops (applied once to twice daily) or idoxuridine ointment. L-lysine supplementation was once widely recommended but recent research has questioned its efficacy, and many veterinary ophthalmologists no longer recommend it.

Antibiotic therapy. For bacterial conjunctivitis caused by Chlamydophila or Mycoplasma, systemic antibiotics are the treatment of choice. Doxycycline given orally for three to four weeks is the standard protocol for Chlamydophila. Topical antibiotic eye drops or ointments, such as erythromycin or chloramphenicol ophthalmic preparations, may be used concurrently. Even when the primary cause is viral, topical antibiotics are often prescribed to prevent or treat secondary bacterial infections of compromised tissue.

Anti-inflammatory therapy. Non-steroidal anti-inflammatory eye drops may be used to reduce conjunctival swelling and discomfort. Corticosteroid eye drops should be used with extreme caution in cats — they can worsen herpesvirus infections and delay healing of corneal ulcers. Your veterinarian will only prescribe steroid-containing eye drops after ruling out these conditions through appropriate testing.

Supportive care at home. Gently cleaning discharge from around the eyes with a warm, damp cloth several times daily keeps the area comfortable and prevents crusting from sealing the eyelids shut. Use a separate cloth for each eye to avoid spreading infection between eyes. Ensure your cat continues eating — warming food slightly can help if nasal congestion has reduced their appetite. A humidifier can ease respiratory congestion in cats with concurrent upper respiratory infection.

Treatment duration varies. Acute bacterial conjunctivitis may resolve within one to two weeks of antibiotic therapy. Herpesvirus-associated conjunctivitis often takes two to three weeks to resolve per episode, and recurrences are common. Chronic cases may require long-term management strategies discussed with your veterinarian.

Prevention of Conjunctivitis in Cats

Complete prevention of feline conjunctivitis is difficult because the primary causative agents — particularly herpesvirus — are ubiquitous in the cat population. However, several strategies can significantly reduce the frequency and severity of episodes.

Vaccination. Core feline vaccines include protection against FHV-1 and feline calicivirus. While vaccination does not prevent infection entirely, it significantly reduces the severity of disease in cats that are exposed. Keeping your cat’s vaccinations current is one of the most impactful preventive measures. A vaccine against Chlamydophila felis is available and may be recommended for cats in high-risk environments such as multi-cat households or breeding facilities.

Stress reduction. Because herpesvirus reactivation is closely linked to stress, minimizing stressors in your cat’s environment helps reduce flare-ups. Provide adequate resources — separate litter boxes, food stations, water bowls, and resting areas — in multi-cat households. Maintain consistent routines. Use pheromone diffusers during periods of anticipated stress such as moves, renovations, or the introduction of new pets.

Hygiene. In multi-cat environments, good hygiene practices reduce transmission of infectious agents. Clean food bowls, water dishes, and litter boxes regularly. Isolate new cats for a quarantine period before introducing them to resident cats. Wash your hands between handling different cats, especially if any are showing signs of illness.

Regular veterinary checkups. Annual or biannual examinations allow your veterinarian to detect early signs of eye problems before they become clinically significant. If your cat has a history of recurrent conjunctivitis, discuss a long-term management plan that may include antiviral prophylaxis during high-stress periods.

Prognosis for Cats with Conjunctivitis

The prognosis for feline conjunctivitis depends heavily on the underlying cause. Bacterial conjunctivitis caused by Chlamydophila or Mycoplasma generally carries an excellent prognosis with appropriate antibiotic therapy. Most cats recover fully within two to four weeks.

Herpesvirus-associated conjunctivitis has a good short-term prognosis — most episodes resolve with treatment — but the long-term outlook includes the reality of potential recurrences. Some cats experience infrequent, mild flare-ups that are easily managed. Others develop chronic, recurrent episodes that require ongoing management. In rare cases, herpesvirus can cause severe corneal disease, including deep ulceration or corneal sequestration (a dark, dead area on the cornea), which may require surgical intervention.

Conjunctivitis caused by allergies or irritants carries a good prognosis if the trigger can be identified and eliminated or managed. Anatomical causes like entropion may require surgical correction for permanent resolution.

The most important factor in prognosis is timely treatment. Untreated conjunctivitis can progress to involve the cornea, potentially leading to ulceration, scarring, and permanent vision impairment. If your cat shows signs of eye discomfort or abnormal discharge, schedule a veterinary appointment rather than waiting to see if it clears on its own. Early intervention leads to better outcomes and less discomfort for your cat.

Frequently Asked Questions

Can cat conjunctivitis spread to humans?

The viruses that most commonly cause conjunctivitis in cats — feline herpesvirus and feline calicivirus — are species-specific and do not infect humans. However, Chlamydophila felis can rarely cause mild conjunctivitis in immunocompromised humans. As a practical precaution, wash your hands after handling a cat with conjunctivitis and avoid touching your face. The risk to healthy humans is extremely low.

Can I use human eye drops on my cat?

No. Human eye drops often contain medications, preservatives, or concentrations that are not safe for cats. Some human eye drops contain ingredients that are outright toxic to cats. Never apply any medication to your cat’s eyes without veterinary guidance. If you cannot get to a veterinarian immediately, gently cleaning the eye area with a warm, damp cloth is the safest thing you can do at home.

Why does my cat keep getting conjunctivitis?

Recurrent conjunctivitis in cats is most commonly caused by feline herpesvirus (FHV-1). After initial infection, the virus remains dormant in nerve tissue and can reactivate during periods of stress, illness, or immune suppression. If your cat experiences frequent episodes, discuss long-term management strategies with your veterinarian, including stress reduction, environmental enrichment, and potentially antiviral prophylaxis during high-risk periods.

Is conjunctivitis in cats an emergency?

Simple conjunctivitis is not typically an emergency, but it does warrant prompt veterinary attention — ideally within a day or two of noticing symptoms. However, certain signs indicate a more urgent situation: a completely closed or swollen-shut eye, a visible white or cloudy spot on the eye surface, sudden vision changes, or an eye that appears to bulge forward. If you see any of these signs, seek veterinary care the same day.

Can indoor cats get conjunctivitis?

Yes. Most cats are exposed to feline herpesvirus as kittens, often before they come into your home, and the virus can reactivate at any time regardless of lifestyle. Indoor cats can also develop conjunctivitis from allergies, irritants like dust or cleaning products, or less commonly from bacterial infections introduced by a new cat in the household. Being an indoor cat reduces exposure to some infectious agents but does not eliminate the risk entirely.

How do I apply eye drops to my cat?

Applying eye drops to a cat requires gentle restraint and a calm approach. Wrap your cat in a towel to limit movement, hold their head steady with one hand, and use the other hand to hold the dropper above the eye. Gently pull down the lower eyelid to create a small pocket and place the drop into that pocket. Avoid touching the dropper tip to the eye. Release your cat and reward them with a treat. If your cat is extremely resistant, ask your veterinarian to demonstrate the technique or discuss alternative medication forms.