A corneal ulcer is a painful erosion of the dog's eye surface that can progress to perforation within days without treatment. Brachycephalic breeds — Bulldogs, Pugs, Boxers, Shih Tzus — are especially prone due to their prominent eyes and reduced blink reflex.
Last reviewed: June 2026
What Is a Corneal Ulcer in Dogs?
The cornea is the transparent outer surface of the eye. A corneal ulcer (also called a corneal erosion or ulcerative keratitis) occurs when the epithelial layer — and sometimes deeper stromal tissue — is damaged or lost. Causes include: trauma (a scratch from a cat, twig, or rough play), entropion (eyelid rolling inward), foreign bodies under the eyelid, dry eye (keratoconjunctivitis sicca / KCS), chemical irritants, and certain bacterial or viral infections.
Corneal ulcers are graded by depth:
- Superficial — epithelial only; heals within 3–5 days with appropriate treatment
- Stromal — partial-thickness; requires medical management and close monitoring
- Descemetocoele — only Descemet's membrane remains; extremely fragile, perforation imminent
- Perforated — full-thickness breach; ocular emergency requiring immediate surgery
As described in Côté's Clinical Veterinary Advisor, any corneal ulcer that does not respond as expected within 5–7 days of initial therapy should be re-evaluated — "indolent" or spontaneous chronic corneal epithelial defects (SCCEDs) in middle-aged dogs require surgical intervention (diamond burr debridement or grid keratotomy) rather than just drops.
Signs of a Corneal Ulcer in Dogs
- Squinting or keeping one eye partially closed (blepharospasm) — the most consistent sign
- Pawing at the affected eye or rubbing the face on furniture
- Excessive tearing or watery discharge
- Redness of the sclera (white of the eye) or conjunctiva
- Cloudiness or haze on the surface of the eye — even a subtle gray/blue tint warrants same-day evaluation
- Visible defect on the corneal surface — though superficial ulcers are often invisible to the naked eye without fluorescein stain
- Sensitivity to light — the dog turns away from bright light
Brachycephalic breeds may show milder blepharospasm despite severe ulcers due to reduced corneal sensation. Any eye abnormality in a Bulldog, Pug, Boxer, Shih Tzu, or Pekingese should be evaluated the same day — these breeds are prone to perforation.
Diagnosis and Treatment
Diagnosis requires a fluorescein stain — a yellow-green dye applied to the eye surface that adheres to areas where epithelium is missing, glowing green under cobalt blue light. Ulcers that stain positively are confirmed on the spot. Additional tests include Schirmer tear test (for KCS/dry eye) and intraocular pressure measurement (to rule out glaucoma, which can look similar).
Treatment depends on depth:
-
Superficial ulcers: broad-spectrum antibiotic eye drops (e.g., triple antibiotic, tobramycin) 3–4 times daily; atropine drops if the dog is in significant pain (reduces ciliary spasm); e-collar to prevent self-trauma. Re-check in 5–7 days. Cost: exam + stain + drops typically $100–300.
-
Stromal ulcers: intensive antibiotic drops; possible serum eye drops to prevent collagenolysis (corneal melting); may add antifungal if fungal origin suspected; more frequent rechecks every 3–5 days. Cost: $300–800 including follow-up visits.
-
Descemetocoele or perforation: Emergency referral to a veterinary ophthalmologist for conjunctival flap or corneal graft surgery. Surgical costs typically $1,500–4,000.
-
SCCEDs (indolent ulcers): Require diamond burr debridement or grid keratotomy under topical anesthesia plus a bandage contact lens. Cost: $300–600 for the procedure.
Systemic pain relief (oral NSAIDs or gabapentin) is often warranted, as corneal ulcers are quite painful.
When to See a Vet
Call your vet today if:
- Your dog is squinting one eye or holding it partially closed
- You see redness, cloudiness, or discharge from one eye
- Your dog is pawing at its face or rubbing its eye on carpet
- Any eye abnormality in a flat-faced (brachycephalic) breed
Go to the ER immediately if:
- The eye suddenly appears very cloudy or milky white throughout
- You can see a visible hole or collapse of the eye surface
- The eye is protruding or bulging abnormally
- Your dog appears to be in severe pain and won't open the eye at all
What's going on with your pet?
Describe symptoms or snap a photo. Voyage tells you urgency, home care, and whether you need a vet.
First, tell us about your pet
Breed and age make a real difference in how Voyage interprets symptoms.
Describe the symptoms
Love it? See everything Voyage can do
Frequently Asked Questions
Can a corneal ulcer heal on its own without treatment? Very superficial ulcers in healthy dogs sometimes heal within 3–5 days, but this should not be assumed without veterinary confirmation via fluorescein stain. Deeper ulcers do not heal on their own and will worsen, potentially perforating within days. Without an e-collar, self-trauma from pawing significantly worsens any corneal ulcer.
How much does treating a corneal ulcer cost? A straightforward superficial ulcer — exam, fluorescein stain, antibiotic drops, and one recheck — typically costs $100–300. Stromal ulcers requiring intensive drops and multiple rechecks run $300–800. Surgical intervention for descemetocoele or perforation at an ophthalmologist costs $1,500–4,000.
What breeds are most at risk for corneal ulcers? Brachycephalic breeds with prominent eyes — Bulldogs, Pugs, Boxers, Boston Terriers, Shih Tzus, Pekingese, and French Bulldogs — are at highest risk. Their shallow eye sockets, reduced ability to close the eyelids completely, and decreased corneal sensation all predispose them to corneal exposure and trauma. Middle-aged Boxers and Labrador Retrievers are predisposed to SCCEDs (spontaneous indolent ulcers).
Can a corneal ulcer cause blindness? Yes, if untreated. Deep stromal ulcers can perforate, causing collapse of the eye and permanent vision loss. Even healed ulcers can leave corneal scarring (leukoma) that reduces vision. Prompt treatment and follow-up are essential to preserve sight.
Why does my dog need an e-collar for an eye ulcer? Dogs instinctively paw at painful eyes. A single pawing episode can convert a superficial ulcer into a deep stromal ulcer or even perforate a descemetocoele. An e-collar (cone) is non-negotiable for the healing period — usually 7–14 days for most ulcers.
Still Not Sure if Your Dog 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 your dog's eye (front-lit, close-up, showing the affected area), 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.