A cat with a corneal ulcer squints, tears constantly, paws at the face, and may have a visible cloudy spot on the eye. Ulcers can deepen and rupture within days, so any cat with these signs needs vet evaluation the same day.
Last reviewed: May 2026
What a Corneal Ulcer Looks Like in a Cat
A corneal ulcer is an erosion or hole in the surface of the eye. Cats with ulcers squint hard or hold the eye fully closed, produce watery or mucousy tearing, and paw at the face. A visible cloudy, white, or gray spot may be seen on the eye surface. The third eyelid often comes up to protect the eye. Roughly 25 to 30 percent of feline corneal ulcers in shelter and outdoor cats are linked to feline herpesvirus reactivation (Helps et al., 2005, JFMS). As described in Ettinger's Textbook of Veterinary Internal Medicine, ulcers can progress from superficial scratches to deep stromal defects within 24 to 72 hours.
Common Causes
The most common cause in healthy adult cats is trauma — a scratch from another cat during a fight, a stray branch on a porch, or rough play. In kittens and immunocompromised cats, feline herpesvirus is a leading cause. Brachycephalic cats (Persians, Himalayans, Exotic Shorthairs) develop ulcers from exposure because their eyes do not fully close, and from eyelid abnormalities. Dry-eye syndrome, foreign bodies under the third eyelid, and chemical irritants round out the list.
How Vets Diagnose and Stage an Ulcer
Vets stain the eye with fluorescein dye, which sticks to any defect in the corneal surface and glows green under blue light. The depth and size of the ulcer determine treatment urgency. Superficial ulcers usually heal in 5 to 7 days. Stromal ulcers (involving deeper layers) and descemetoceles (down to the deepest layer before perforation) are sight-threatening and may need surgical referral. Routine wellness exams help catch chronic eye changes (AAFP-AAHA Feline Life Stage Guidelines, 2021).
Treatment and Home Care
Treatment includes topical antibiotic drops (oxytetracycline or tobramycin) every 4 to 6 hours, oral pain medication (buprenorphine or gabapentin), and an Elizabethan collar to prevent further rubbing. Topical antiviral drops (cidofovir, idoxuridine) are added if herpesvirus is suspected. Atropine drops may be used to dilate the pupil and relieve pain. Steroids are absolutely contraindicated — they melt corneas with ulcers. Deep ulcers may need surgical procedures like a conjunctival graft.
When to See a Vet
Not every symptom is a midnight emergency, but some warrant same-day attention and a few are true ERs. Use the lists below to sort which bucket you're in.
Call your vet today if:
- Cat squinting or holding one eye closed
- Watery or pus-like discharge from one eye
- Pawing at the face or rubbing eye on furniture
- Visible cloudy, gray, or white spot on the cornea
- Third eyelid coming across the eye
Go to the ER immediately if:
- Visible blood inside the eye or eye contents protruding
- Sudden eye swelling, severe redness, or eyeball appears larger
- Eye injury from a known trauma (cat fight, stick, chemical splash)
- Cat is in obvious severe pain — vocalizing, hiding, won't eat
- Brown or black tissue visible on the cornea (suggests deep ulcer or sequestrum)
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Frequently Asked Questions
Can a cat corneal ulcer heal without treatment?
Very superficial scratches sometimes do heal on their own in healthy cats, but the risk of bacterial infection and progression to a deep ulcer is high. Without antibiotic drops, a small ulcer can become a sight-threatening problem within 48 hours. Always have an eye that has been visibly painful for more than a few hours evaluated.
How much does cat corneal ulcer treatment cost?
Initial vet exam with fluorescein staining runs $80–200. Topical antibiotic drops are $20–60 per bottle and antiviral drops (cidofovir) add $80–150. Oral pain medication adds $30–80. An Elizabethan collar is $15–30. For superficial ulcers, total cost is typically $150–400. Deep ulcers requiring surgery (conjunctival graft) run $1,500–3,500 with a veterinary ophthalmologist.
How long does a corneal ulcer take to heal?
A superficial ulcer typically heals in 5 to 7 days with consistent drop application. Stromal (deeper) ulcers take 2 to 4 weeks and may need multiple recheck visits with repeat staining. Indolent ulcers — common in middle-aged cats — can take 4 to 8 weeks and often need debridement. The eye should be rechecked 5 to 7 days after starting treatment.
Can I use human eye drops on my cat?
No. Many human over-the-counter eye drops contain steroids, vasoconstrictors, or preservatives that can worsen a corneal ulcer or cause it to perforate. Use only drops prescribed for your cat after a vet has confirmed the diagnosis with fluorescein staining.
Still Not Sure if Your Cat Needs a Vet?
When you're not sure if this is wait-and-see or call-tonight, Voyage AI Vet triages in under 2 minutes. Describe what you're seeing in chat, share photos of the affected eye in good light, both eyes side by side for comparison, or any discharge, or hop on a live video call if you want a second pair of eyes. Every answer comes with citations to the actual veterinary literature it's pulling from — so you see exactly where the guidance comes from, not just a chatbot's word.