Understanding Corneal Ulcer in Dogs

A corneal ulcer is an open wound on the surface of your dog’s eye, and it can range from a minor scratch that heals within days to a serious injury that threatens vision. If your dog is squinting, pawing at their eye, or their eye looks red or cloudy, it’s worth getting a vet to take a look quickly. The sooner a corneal ulcer is identified and treated, the better the outcome.

What is a corneal ulcer?

The cornea is the clear outer surface of the eye that lets light in. A corneal ulcer is a wound in that surface, and depending on how deep it goes, it can be a minor issue or a genuine emergency.

The cornea has several layers. Most superficial ulcers affect only the outermost layer, called the epithelium, and heal relatively quickly with the right treatment. Deeper ulcers that reach the stroma (the thick middle layer) take longer to heal and carry a higher risk of complications. The deepest and most serious type, called a descemetocele, occurs when the ulcer erodes all the way down to a very thin membrane just before the eye perforates entirely. This is a surgical emergency.

Left untreated, a severe corneal ulcer can lead to permanent vision damage or loss of the eye.

Symptoms of corneal ulcers in dogs

Here’s what to look for:

• Squinting or keeping one eye partially or fully shut
• Pawing or rubbing at the affected eye
• Excessive tearing or watery discharge
• Colored discharge, yellow or green, coming from the eye
• Redness around the eye
• A cloudy or hazy appearance to the eye
• Reluctance to have the eye touched

Deeper ulcers don’t always look more dramatic on the outside, which is one of the reasons a vet exam matters even if symptoms seem mild. If the eye looks significantly worse suddenly, treat it as an emergency.

Causes of corneal ulcers

Corneal ulcers have several possible causes:

• Trauma: Scratches from plants, debris, or another animal are among the most common causes. Dogs who spend time in long grass or undergrowth are particularly exposed.
• Dry eye (keratoconjunctivitis sicca, or KCS): When the eye doesn’t produce enough tears to stay properly lubricated, the corneal surface dries out and becomes vulnerable to ulceration. This is a common underlying cause that needs to be treated alongside the ulcer itself.
• Eyelid abnormalities:
  • Entropion: When the eyelid rolls inward, the eyelashes rub continuously against the cornea.
  • Distichiasis: Extra eyelashes growing from the eyelid margin that contact and irritate the eye.
  • Ectopic cilia: Hairs that grow through the inner eyelid surface and press directly against the cornea with every blink.
• Infections: Bacterial infections can both cause and significantly worsen corneal ulcers.
• Chemical exposure: Accidental contact with cleaning products or other irritants.

Some breeds are at higher risk than others. Flat-faced breeds like Pugs, French Bulldogs, English Bulldogs, Shih Tzus, and Pekingese have prominent eyes and shallow eye sockets, which makes them more prone to trauma and dryness. Boxers, Corgis, and Golden Retrievers are more prone to a specific type called indolent ulcers (more on those below).

How corneal ulcers are diagnosed

The standard diagnostic tool is a fluorescein stain test. Your vet applies a harmless orange dye to the eye, which glows bright green under ultraviolet light wherever the corneal surface is damaged. It’s quick, painless, and shows the size and location of the ulcer clearly. It also helps identify descemetoceles, which appear as a dark central area surrounded by green staining, a critical distinction for treatment planning.

Treatment for corneal ulcers in dogs

Not all corneal ulcers are the same, and treatment is guided by type and severity.

Type	What it is	How it’s typically treated
Superficial ulcer	Affects only the outer epithelial layer	Antibiotic eye drops, pain relief, and an E-collar to prevent pawing. Most heal within 3 to 7 days
Stromal ulcer	Penetrates into the deeper layers of the cornea	More intensive medication; may require surgical support like a conjunctival flap (where a small piece of the tissue covering the white of the eye is stitched over the ulcer to help it heal)
Descemetocele	Erodes to the deepest layer just before perforation	Surgical emergency. Requires immediate intervention to prevent the eye from rupturing
Indolent ulcer (SCCED)	A superficial ulcer that won’t heal because the outer layer can’t adhere properly to the tissue beneath	Debridement (gentle removal of the loose epithelium), grid keratotomy (a series of tiny scratches to stimulate healing), or therapeutic contact lenses
Melting ulcer	Bacterial enzymes break down and liquefy the corneal tissue	Aggressive treatment with frequent antibiotic and anti-enzyme drops, and often emergency surgery. Treated as a time-critical emergency

An E-collar is an important part of recovery for all types. It prevents your dog from rubbing or pawing at the eye, which can turn a healing ulcer into a much more serious one. Avoid any human eye drops unless specifically prescribed by your vet — many over-the-counter products contain ingredients that are harmful to dogs.

When corneal ulcers are an emergency

Go to a vet immediately if:

• The eye appears to be bulging or the surface looks irregular
• There is thick green or yellow discharge
• Your dog won’t open the eye at all
• Symptoms are worsening quickly despite treatment

These signs can indicate a melting ulcer, descemetocele, or corneal perforation, all of which require urgent care.

Does pet insurance cover corneal ulcers?

Vet care for eye injuries, especially surgeries, can be pricey. The good news? Lemonade Pet Insurance covers accidents and illnesses, including corneal ulcers, as long as the condition isn’t pre-existing. If you’re not already covered, it’s a good idea to get a policy in place; because let’s face it, life happens.

Before we go

Corneal ulcers in dogs can feel overwhelming, but with prompt care, most pups recover well. If you notice anything unusual with your dog’s eye, don’t wait-reach out to your vet. And if vet costs are a concern, getting pet insurance before anything happens can make a world of difference in times like these.

Frequently Asked Questions

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