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How to Tell if a Canine Corneal Ulcer Is Healing

| Updated September 26, 2017

A corneal ulcer is a small hole in the cornea -- the clear, dome at the front of your dog's eyeball. If your dog is being treated for a corneal ulcer, it's vital to attend all follow-up examinations with your veterinarian. Because the cornea is clear, it can be difficult to see the ulcer. Your vet can perform a simple, and safe, fluorescein stain test to ensure the ulcer is healing.

Causes of Corneal Ulcers

Corneal ulcers are commonly caused by a trauma, such as your dog rubbing her eye on the carpet, from a cat scratch or contact with something sharp. Chemical irritants or substances such as shampoo also can burn the cornea. Bacterial infections, viral infections or other diseases can cause ulcers as well.

Physical Symptoms

Corneal ulcers are painful and can affect your dog in a number of ways. Symptoms to watch for include:

  • Keeping the eye closed to protect it.
  • Squinting.
  • Excessive tearing.
  • Rubbing the eye on the carpet or with her paw.
  • Cloudy cornea.
  • Redness to the white of the eye.
  • If the eye becomes infected, there may be a purulent -- pus -- discharge.


  • If you notice any signs of a corneal ulcer or other changes in one or both of your dog's eyes, take her to a veterinarian for evaluation and treatment as soon as possible. Corneal ulcers can cause permanent sight loss.


Your veterinarian will examine the eyes to determine the extent of the damage to the cornea and check for signs of trauma or disease that may have caused the ulcer.

A fluorescein stain test generally is used to diagnose a corneal ulcer. A drop of a sterile greenish-yellow dye called fluorescein is placed on the cornea. Some vets use a small strip of paper coated with dye, and gently touch the surface of the eye with the strip to apply the dye. The dye will run off the surface of the intact cornea, but sticks to ulcerated areas. Once stained, large ulcers are clearly visible and small ones can be viewed under ophthalmic lights and filters. The test is quick and painless.

If the ulcer is chronic or very deep, your veterinarian may take samples for culture before staining the eye.

Types of Treatment

Treatment for a corneal ulcer depends on how long your dog has had the condition and the severity of the damage.

Superficial Ulcers

Acute, superficial ulcers generally heal in three to five days, but can take longer. They generally leave minimal scaring. Your veterinarian usually will prescribe an ophthalmic antibiotic ointment, applied every four to six hours, to prevent bacterial infection. He also may prescribe atropine drops or ointment, applied twice a day, to relieve pain and spasms.


    • To apply drops or ointment, hold your dog firmly and tilt her head upwards. 
    • Gently pull the eyelids apart with the thumb and forefinger of the hand holding her head. 
    • Place a single drop of medication on the surface of the eye with your other hand. 
    • Hold the top of the tube parallel with the eye, rather than pointing directly at it. 
    • Be careful not to touch the eye with the dropper, as it could damage the eye or bacteria from the eye could go into the ointment.

If your dog paws or rubs her eye on the floor, she will need to wear an Elizabethan collar while the ulcer is healing.

Deeper Ulcers

If your dog has a deeper ulcer, your veterinarian, along with prescribing antibiotics and atropine, may protect the eye while it heals, by suturing the eyelids closed or by covering the eye with part of the eyelid lining. If the ulcer is slow to heal, your vet may stimulate healing by freshening up the ulcer. He will remove any loose tissue and, with a fine needle, make small dot-like scratches to the exposed area so new skin cells can get a hold. This can usually be done with a local anesthetic. Deeper ulcers can leave a scar on the cornea, causing impaired vision.

On rare occasions, a really deep ulcer can lead to a ruptured eyeball or cause severe pain, which can't be controlled. Your veterinarian usually will recommend removing the eye if that is the case. A dog can cope well with one eye, and quickly will get back to life as normal after her operation.

Monitoring Healing is Vital

Once treatment has started, your dog will need to be re-examined after two to three days. The veterinarian will repeat the fluorscein stain test to check if the ulcer is healing. Further tests will be done until the ulcer is healed. Don't be tempted to discontinue treatment without your vet's consent.


  • It's important to observe your dog at home between examinations. If you notice a discharge, the eye suddenly becomes more painful or doesn't look right in any way, go back to your veterinarian straightaway.

Red Lines Around the Ulcer

When a deeper ulcer starts to heal, you may notice red lines covering the cornea and going to the ulcer. Normally, there aren't any blood vessels in the cornea, but the body will form new vessels over the surface of the eye to speed healing. If the blood vessels remain once the ulcer has healed, your vet may prescribe corticosteroid drugs or ointment to reduce them. If the eye becomes painful after using corticosteroids, immediately stop using them and go back to your veterinarian.