Cat Eye Discharge: URI, Corneal Ulcer, or Herpesvirus?
Eye discharge in a cat is almost never just "a bit goopy." It's almost always one of three clinical conditions — each with different urgency, treatment, and long-term implications. Getting the right one matters because the wrong treatment can make feline eye disease much worse.
The three common culprits
1. Feline upper respiratory infection (URI)
Presentation: watery then mucopurulent (yellow/green) discharge from one or both eyes, with nasal discharge, sneezing, reduced appetite, possibly fever. Cats often squint.
Cause: most commonly feline herpesvirus (FHV-1) or calicivirus, sometimes bacterial (Chlamydophila, Mycoplasma, Bordetella).
Urgency: vet visit within 24–48 hours. Supportive care plus antiviral/antibiotic eye drops.
2. Corneal ulcer
Presentation: one eye, squinting shut (sometimes completely), excessive tearing, visible haze on the cornea, pain (cat rubs eye or avoids light). No sneezing.
Cause: trauma (cat scratch, plant matter, self-rubbing), FHV-1 reactivation, dry eye, or secondary bacterial infection.
Urgency: same-day vet visit. Corneal ulcers can deepen rapidly and lead to perforation.
3. Feline herpesvirus flare (FHV-1)
Presentation: typically one eye, chronic or recurrent, mild-to-moderate discharge, squinting, often recurs under stress. Most cats are exposed in kittenhood and carry the virus for life.
Urgency: vet visit within a few days. Chronic cases benefit from lysine supplementation and stress reduction.
Key detail: FHV-1 can cause dendritic corneal ulcers with a characteristic branching shape — visible only with fluorescein stain at the vet.
Quick differentiation guide
| Sign | URI | Corneal ulcer | FHV-1 flare |
|---|---|---|---|
| One or both eyes | Often both | One | One |
| Sneezing | Yes | No | Sometimes |
| Squinting | Mild/moderate | Severe | Moderate |
| Discharge | Yellow/green mucopurulent | Often watery | Watery to yellow |
| Pain level | Moderate | High | Moderate |
| Recurrence | Acute | One event | Chronic/recurrent |
Don't-miss causes
- Glaucoma — enlarged eye, severe pain, vision loss. Emergency.
- Uveitis — often secondary to FIP, FeLV, FIV, toxoplasmosis.
- Foreign body — severe squinting, usually one eye. Same-day vet.
- Tear duct blockage — chronic watery discharge. Brachycephalic breeds prone.
- Entropion (inward-rolled eyelid) — chronic irritation.
- Eyelid tumor — older cats, visible lump.
- Eye visibly bulging or enlarged
- Eye looks sunken or smaller than the other
- Significant blood from the eye
- Cat won't open the eye and it's getting worse by the hour
- Visible foreign object on or in the eye
- Pupil fixed (non-responsive to light change)
- Trauma to head or face
- Kitten with both eyes gummed shut and not eating
What you can do at home (while waiting)
- Gently wipe discharge with a warm, damp cotton pad
- Use a separate pad per eye
- Do NOT use human eye drops or saline contact solutions
- Do NOT flush with hydrogen peroxide or alcohol
- Keep other pets separate (herpesvirus and chlamydia are contagious)
- Reduce stress
Triage your cat in under 60 seconds
Not sure if this is an emergency? CatMD runs feline-specific triage on symptoms or photos and returns a 0–99 health score with urgency tier, differentials, and a vet-ready summary.
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