What are the common causes of conjunctivitis in cats?

Conjunctivitis is commonly caused by infection (viral or bacterial), allergies, foreign bodies, or eye irritation. The exact cause must be confirmed by your vet through examination and testing before appropriate treatment can be decided.

Can conjunctivitis spread to other cats in the household?

Some forms of infectious conjunctivitis are contagious. If you have other cats at home, it is advisable to separate them and seek a vet evaluation promptly to reduce the risk of spread.

How long does it usually take for conjunctivitis to resolve?

Recovery time depends on the cause. Mild infectious or irritant conjunctivitis typically improves within 1–2 weeks; cases involving corneal involvement or systemic infection may take longer and require close follow-up as directed by your vet.

What records or preparations can I make before the appointment?

Take photos and videos of the eye, note when you first noticed the problem and how the discharge has changed, and bring your observations to the vet. Avoid administering any medications on your own.

How much do the tests and treatment usually cost?

Costs vary by clinic and region — ask your vet for an estimate before proceeding.

Disease Guide

Cat Conjunctivitis: Symptoms, Eye Discharge & Treatment Guide [2025]

Cat conjunctivitis is commonly caused by herpesvirus or Chlamydia, leading to red, swollen eyes and discharge — topical eye treatment is usually effective.

Take 1 minute to check the symptoms first

Last updated: 2026/01/05

Pethealthmap Editorial Team

Sources: ISFM, AAHA, National Taiwan University Veterinary Hospital

When to See a Vet

Seek emergency care immediately

•Eyeball rupture or significant bleeding around the eye
•Eye completely closed with no response at all
•Severe and persistent pain — constant crying or refusal to eat

Schedule a clinic visit soon (within 24–72 hours)

•Heavy thick or purulent (pus-like) eye discharge
•Frequent pawing at the eye or obvious scratching behavior
•Persistent eye redness and swelling with prolonged inability to open the eye

01What symptoms indicate something is wrong?

Conjunctivitis typically presents with eye discharge and discomfort, accompanied by redness and squinting.

Increased thick or purulent eye discharge, with crusting often visible in the morning
Noticeable redness or swelling of the conjunctiva, with visible blood vessels in the whites of the eyes
Frequent squinting, reluctance to open the eye, or sensitivity to light
Repeatedly pawing or rubbing the eye with a front paw
Apparent vision impairment — bumping into furniture or missing objects when reaching
If symptoms persist or worsen, schedule a vet appointment promptly

Seek emergency care immediately if you notice the following symptoms:

⚠️ Ruptured eyeball or heavy bleeding around the eye
⚠️ Eye completely shut with no response to stimulation
⚠️ Severe, ongoing pain — continuous vocalisation or refusal to eat

02What to Watch For at Home: Observation Tips and When to Seek Emergency Care

Recording daily behaviour and eye changes before the vet visit helps the vet assess the condition quickly.

Note any changes in alertness or interaction with people (lethargy or withdrawal)
Track appetite and water intake daily, noting any refusal to eat
Monitor litter box habits and check for any other systemic symptoms
Watch for reduced activity or reluctance to jump or move around
Weigh your cat daily and record the numbers to share with your vet
Take close-up photos and short videos of the eye with your phone to document how symptoms progress, and bring them to the appointment

03How Will the Vet Diagnose the Condition? Common Tests and Procedures

The vet will begin with an eye examination and general physical check, with further sampling or imaging ordered if needed.

Ophthalmic physical examination

assessment of the eyelids, conjunctiva, cornea, and tear production

Corneal staining and conjunctival cytology to check for surface damage or signs of infection

Viral or bacterial PCR and culture testing to identify infectious causes

Ocular ultrasound or CT scan of the head and neck to evaluate deeper or structural lesions

Blood tests and general physical examination to assess for any underlying systemic disease

04Treatment and Care After Diagnosis: Medications, Diet Adjustments, and Home Care

Treatment varies by cause — it is important to administer medications as directed and attend follow-up appointments regularly.

Treatment is tailored to test results; medications such as corticosteroids must only be used as prescribed by your vet
Topical medications or eye drops must be applied on schedule as instructed and the full course must be completed
Severe cases or those with systemic signs may require hospitalisation for monitoring and nursing care
Attend scheduled follow-up visits to monitor corneal healing and vision recovery, preventing delays or recurrence
If symptoms do not improve, your vet may refer you to a veterinary ophthalmologist for specialist assessment

05What to Prepare Before the Vet Visit: Key Information to Help Your Vet Quickly Identify the Cause

Take clear photos and several short videos of the eye with your phone (close-up and side views)

Note the date you first noticed the problem and track how symptoms have changed over time

Describe the discharge — its colour, amount, and consistency (thick, watery, or purulent)

Note any obvious changes in vision or behaviour

Record pain responses when the eye is touched and how often they occur (e.g. pulling away or raising a paw)

Bring any previous ophthalmic examination reports or records of medications used, if available

This content is for reference only and cannot replace a professional veterinary diagnosis. If your pet shows signs of illness, please seek veterinary care promptly.

Related Symptoms (You May Also Be Looking For)

Blepharospasm

Eyelid spasm

Conjunctivitis

Eye inflammation

Ocular Discharge

Eye discharge