What causes eye discharge and squinting in cats?
The vast majority of eye discharge and squinting in cats is caused by feline herpesvirus, chlamydia-driven conjunctivitis, or a corneal scratch - especially in kittens and multi-cat households. A cat that is holding an eye shut, has a visibly cloudy cornea, or has a swollen third eyelid needs a vet within 24 hours because feline corneal ulcers deteriorate fast.
This page is general pet health information, not a diagnosis or treatment plan for your pet. Always confirm anything urgent with a licensed veterinarian.
When to see a vet today
See a vet today if you notice Eye held shut or a visibly bulging third eyelid, Cloudy, dull, or blue-tinged cornea, and Thick yellow-green discharge in both eyes plus sneezing and lethargy. These are the signs that should not wait for home care or a watch-and-see approach. If any of them appear, skip the rest of this guide and call your vet or an emergency clinic now - waiting is the risky option.
- ●Eye held shut or a visibly bulging third eyelid
- ●Cloudy, dull, or blue-tinged cornea
- ●Thick yellow-green discharge in both eyes plus sneezing and lethargy
- ●Any eye trauma from a cat fight or a scratch
Safe to monitor at home
Milder signs are usually safe to watch for a day or two: Small brown tear stains in the corner of one eye, Occasional clear watery tearing after grooming, and Mild squint that resolves within a few hours. Keep notes and photos so you can spot a trend. Anything that worsens, spreads, or comes with appetite, energy or behavior changes moves out of this category and into a vet visit.
- ●Small brown tear stains in the corner of one eye
- ●Occasional clear watery tearing after grooming
- ●Mild squint that resolves within a few hours
What to photograph or record
Photograph or record Straight-on photo of both eyes with natural light, Close-up of the affected eye - get the third eyelid in frame, and Photo of any nasal discharge if present in good, even light. Clear, well-framed evidence is what lets a vet - or a PetSenseAI scan - judge the change instead of guessing from a description. The checklist below is the exact shot list.
- Straight-on photo of both eyes with natural light
- Close-up of the affected eye - get the third eyelid in frame
- Photo of any nasal discharge if present
- 5-second video showing blinking rate
Likely causes
The causes vets consider first for this presentation are feline herpesvirus (fhv-1), chlamydia felis conjunctivitis, corneal ulcer, and blocked tear duct. Most are manageable once identified, but they look similar from the outside, which is why a photo-based triage and, when needed, an exam matter more than guesswork.
Feline herpesvirus (FHV-1)
The number-one cause of feline eye disease. Recurs during stress. Often paired with sneezing.
Chlamydia felis conjunctivitis
Bacterial cause common in kittens and shelters. Very red pink tissue, sticky discharge, one eye first.
Corneal ulcer
Cat fight scratches or self-trauma from face-rubbing. Painful - cats squint hard and hide.
Blocked tear duct
Common in Persians and flat-faced breeds. Chronic clear tearing and rust-colored stains, no pain.
Safe home care
For mild cases, safe home care is wipe discharge with a warm damp cotton pad, one pad per eye to avoid cross-contamination, reduce stress - feeding schedule, quiet room, feliway diffuser - because herpesvirus flares with stress, and isolate from other cats until diagnosed if multiple cats are affected. These steps comfort and monitor; they do not treat the underlying cause. Stop home care and call a vet if anything in the urgent list above appears or the trend moves the wrong way.
- -Wipe discharge with a warm damp cotton pad, one pad per eye to avoid cross-contamination
- -Reduce stress - feeding schedule, quiet room, Feliway diffuser - because herpesvirus flares with stress
- -Isolate from other cats until diagnosed if multiple cats are affected
- -Never use dog eye drops or human antibiotic drops without a vet's direction
PetSenseAI is a triage and monitoring tool, not a substitute for veterinary care. Always confirm treatment plans with a licensed veterinarian.
Frequently asked
Why does my cat have a brown crust in the corner of its eye?
Normal cat tears oxidise into a rusty-brown crust and are usually harmless - especially in flat-faced breeds like Persians. It only needs a vet if the crust is thick yellow-green, if the eye is squinty, or if it appears suddenly in a previously clear eye.
Can I use human saline to clean my cat's eye?
Yes - preservative-free 0.9% sterile saline (the contact-lens rinse type) is safe to flush debris. Warm it slightly in your hand first. Avoid contact-lens cleaning solutions, tap water, and any medicated drops.
Is feline herpesvirus contagious to my other cats or to me?
FHV-1 spreads between cats through sneezing, shared bowls, and grooming, and most cats carry it for life once infected. It does not infect humans or dogs - it is species-specific.
When is squinting an emergency in a cat?
Treat it as urgent if the eye is fully shut for more than a few hours, the cornea looks cloudy, the pupil is a different size to the other, or the eye follows a bite wound. Feline ulcers can perforate within 48 hours.
Related symptom guides
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Start a scanPetSenseAI is an AI-assisted triage and monitoring tool. It does not diagnose, treat, cure, or prevent any condition. Always consult a licensed veterinarian for any medical concern about your pet.
If your pet is in distress - collapse, laboured breathing, seizures, uncontrolled bleeding, suspected poisoning, bloat, or trauma - stop and contact an emergency veterinarian or a poison control line immediately. Do not wait for a scan result.