The cornea is the clear membrane that covers the front of the eye. It has three layers. A corneal ulcer is an abrasion that reaches into the second layer of the cornea. Surface damage is called a corneal erosion or abrasion. If the damage extends to the third, innermost layer of the cornea, the damage is irreparable. Proper diagnosis and treatment of corneal ulcers are critical to preserve your dog's vision.
Corneal ulcers are painful to a dog. He will be sensitive to light and may paw at his eye or keep the eye closed. The eye may appear red, swollen or watery, or may have a film over it.
Veterinarians diagnose a corneal ulcer with a physical examination and by applying diagnostic dyes to the eye, commonly the dye fluorescein. After application, any ulcerated part of the eye turns green. Your vet may also test samples for bacterial or fungal infections or order blood work to check for viral infections.
Corneal ulcers are usually caused by trauma to the eye. Other potential causes include infection, foreign bodies, chemical burns and tear deficiency.
Ulcers may also be caused by rubbing of eyelashes against the eye. Boxers are prone to this condition, and it is also seen in breeds including pugs, bulldogs, Boston terriers and shih tzus.
If the damage is minor, such as a corneal abrasion, the eye should heal within three to five days. Your vet may prescribe an antibiotic eye ointment to prevent infection during recovery. Atropine ointment may also be applied to relieve pain from the abrasion. Untreated, corneal abrasions may develop into ulcers.
Corneal ulcers may require surgery to repair the cornea. Antibiotic ointment may be applied to prevent infection along with medication to increase tear production and decrease inflammation.
A vet may put a contact lens in your dog's eye to protect the cornea and promote healing. If your dog is pawing at his eye, he may have to wear a collar to prevent further damage to the eye.
As part of the healing process, your dog may develop new blood vessels in the eye; they increase healing of the ulcer. These appear as red streaks in the eye. After the ulcer is healed, your vet may prescribe corticosteroid eye ointment to reduce the size of the blood vessels.
In some cases, the corneal ulcer fails to heal due to an underlying condition resulting in an indolent ulcer. Some conditions that may prevent healing include glaucoma, insufficient tear production and other eye diseases. Indolent ulcers are common in boxers, corgis and Samoyeds.
To treat these ulcers, your vet may perform a procedure that involves scraping off the surface of the cornea and roughening the surface with a needle. Medications, including antibiotics and agents that help the layers of the cornea adhere to each other, are then applied to the eye. A collagen shield, similar to a contact lens, is applied to act as a bandage for the eye.