Corneal Eye Ulcer (Ulcerative Keratitis) in Dogs

Key Takeaways

The cornea is the clear outer layer of the eye which acts as a protective barrier. When the cornea loses cells and thins out, it is called a ‘corneal eye ulcer,’ or ulcerative keratitis. 

• Corneal ulcers can be painful and may cause pawing at the affected eye or rubbing it on a carpet which can cause the condition to worsen

• Severe corneal ulcers are more susceptible to infection and other complications which may result in irreparable damage to the eye

• Fluorescein stain is used to characterize the ulcer during an ophthalmic exam

• Medication may be sufficient to treat mild cases, but surgery is often necessary

• Complicated cases have a guarded prognosis, and it may not be possible to prevent loss of vision in the affected eye

• Early treatment improves the chances for a good outcome

A Closer Look: What are Corneal Eye Ulcers in Dogs?

Eye ulcers in dogs are usually caused by injury. Damage to the eye from various sources,such as blades of grass, sticks, or a dog’s own nail or hair can all damage the cornea, leading to an ulcer. 

The risk posed by a corneal eye ulcer is variable, depending on how severe it is. A simple, small ulcer may heal on its own, while complicated ulcers may result in the loss of the eye. A dog may make a mild corneal ulcer worse by rubbing at it in distress.

Severe ulcers may take weeks to months to recover, and require multiple procedures during that time. Even with aggressive surgical intervention, it may not be possible to prevent vision loss. Early detection is key in order to determine the severity of the corneal ulcer and have the best chance of treating it.

Risk Factors

Dog breeds with longer hair or larger, bulging eyes are more susceptible to ulceration. As well, anything that interferes with normal blinking or tear production are predisposing factors to corneal ulcers.

Mild signs of discomfort, pain, rubbing at the eye may occur with simple ulcerative keratitis. The third eyelid may cover much of the eye as it is reflexively drawn deeper into the eye socket (enophthalmos).  

In more complex cases, there also may be mucus or pus draining from the eye, and the cornea changes from clear to cloudy. New blood vessels growing into the cornea create a pink haze to the cornea as the condition progresses.

Possible Causes

Injuries are the most common cause of a corneal eye ulcer. 

Other potential causes include:

• Dry eye (Keratoconjunctivitis Sicca (KCS))

Eyelid and eyelash disorders

Facial nerve paralysis

• Irritants, such as chemicals, dust, smoke, or other foreign bodies

• Infections, including conjunctivitis due to bacterial, viral, or fungal agents

Main Symptoms

Severe corneal ulcers are easy to identify, with clearly visible indentations on the outer surface of the eye. Smaller corneal ulcers are harder to see, and staining with fluorescein dye is necessary to reveal the full extent of the ulcer.

Other signs that a dog has a corneal ulcer include:

Excessive tearing (epiphora)

Excessive blinking (blepharospasm)

• Reddened, irritated eyes (ocular inflammation)

Testing and Diagnosis

An ophthalmic exam is used to diagnose ulcerative keratitis. Fluorescein dye washes off a healthy, intact cornea, so staining is necessary to identify and determine the depth and extent of a corneal ulcer. Other tests run during an ophthalmic exam include:

• Schirmer tear test

• Measurements of internal eye pressure 

• Checking blink reflexes

• Bacterial culture from the cornea

• Cytology of cornea sample

Steps to Recovery

Unlike other injuries, a dog’s eye cannot be bandaged. This, coupled with the discomfort a corneal ulcer causes, makes recovering from a corneal ulcer difficult. Pawing, scratching, or rubbing at the eye can complicate or worsen an ulcer, delaying recovery or worsening the condition. E-collars are an almost universal treatment tool used during recovery from corneal ulcers to try and minimize such interference. Similarly, the third eyelid is often surgically tacked to the upper eyelid to cover the damaged cornea and provide an optimal environment for healing. 

Topical antibiotics are applied to prevent or treat infections, and analgesics are used to manage pain. Additional surgical procedures may be necessary for complicated ulcers, with multiple procedures performed over time. Referral to a veterinary ophthalmologist may be advised. 

The prognosis for a simple corneal eye ulcer is positive, with healing expected within 7-10 days, barring complications. Rechecks for repeated fluorescein staining are necessary to monitor progress. 

The prognosis for complex cases is guarded. After surgical treatment, follow-up appointments may be required at intervals for days or months to verify that the eye is recovering properly. Multiple procedures may be required over this time.

Particularly deep ulcers can cause irreparable damage, necessitating complete removal of the eye.


Corneal ulcers are most commonly caused by external irritants coming into contact with a dog’s eye. Keeping long hair trimmed away from a dog’s eyes can help prevent the condition, and checking a dog’s eyes after they have been running through long grass can catch corneal ulcers early.

Some breeds with protuberant (prominent) eyes are more at risk. Corneal ulcers are not contagious.

Are Corneal Eye Ulcers Common in Dogs?

Corneal ulcers are common in dogs.

Typical Treatment

• Eye drops

• Topical and oral analgesics

• Anti-inflammatories

• Surgery

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