The cornea is the transparent, shiny membrane that makes up the front of the eyeball. Although the cornea is like a clear windowpane it is made up of many layers of highly specialised skin cells. A corneal ulcer is an erosion of these layers either superficially involving only a few top layers or a deep ulcer involving the entire cornea. Deep ulcers are very serious, if a deep ulcer ruptures then the liquid inside the eyeball will leak out causing irreparable damage.

Causes of corneal ulcers

The most common cause is trauma to the eye. This comes in the form of scratches, blunt trauma, self-trauma or burns from chemicals. Trauma to the cornea can also occur from foreign bodies within the eye socket (e.g. grass seeds) or eyelashes rubbing on the eye.

Less common causes are secondary to infections, canine dry eye and hormonal diseases. Brachycephalic (flat faced) breeds tend to be more prone due to them having more prominent eyes.

Signs and diagnosis of corneal ulcers

Corneal ulcers are very painful, and most dogs will rub at the eye and look squinty. The eye will likely have a discharge and look either red or blue.

We use special stains to diagnose the presence of an ulcer. A drop of fluorescein green stain is placed on the cornea and it will adhere to any areas of ulceration, so they are now visible to the eye.


Superficial ulcers will generally heal within 3-10 days with medical care. Treatment involves antibiotic eye drops/ointment applied regularly to prevent infection, atropine to dilate the pupil for comfort, pain relief medications, and an Elizabethan collar to prevent self-trauma.

Deep and chronic ulcers will often need more aggressive treatment with the addition of medications such as plasma eye drops, oral antibiotic tablets and clerapliq corneal bandaid. It is not uncommon for these types of ulcers to require surgical intervention to encourage healing and provide a physical protective barrier. We may recommend referral to a specialist ophthalmologist.

Follow-up care is crucial

Treatment will need to be continued until the fluorescent stain is negative, so it is very important to have regular follow up vet appointments until your dog has been given the all clear.ย  Corneal ulceration can suddenly worsen and can quickly become catastrophic for vision and eye function. Ulcers that donโ€™t heal will need further investigation for the underlying cause.