What is ulcerative keratitis?
Ulcerative keratitis is a kind of inflammation that is associated with ulceration of the cornea. The cornea is the transparent outer layer of the eye and is composed of three distinct layers of cells:
- The top surface is called the corneal epithelium.
- The middle layer is the thickest of the three and is called the corneal stroma.
- The inner layer is quite thin and is called the corneal endothelium.
A corneal ulcer occurs when the corneal epithelium is disrupted, resulting in a loss of epithelium and some stroma (see handout “Corneal Ulcers in Dogs”). When a dog rubs its eyes, the eyes should be carefully examined, and a special stain called fluorescein may be used. If there is damage to the surface of the cornea, the fluorescein stain will stick to the underlying cells and show up as a temporary green glow in the areas of cell trauma.
Are some breeds of dog more likely to develop this condition?
While no specific genetic predispositions to developing ulcerative keratitis have been identified, there are some breeds that seem to develop them more commonly, particularly breeds with short muzzles and prominent eyes such as pugs and Boston terriers. If the condition occurs in a middle-aged to older dog without an injury to the eye, it can signal a long-term degenerative condition of the cornea. Also, ulcerative keratitis may be the result of a chronically low level of tear production (keratoconjunctivitis sicca or dry eye).
What are the signs of ulcerative keratitis?
The signs of ulcerative keratitis depend somewhat on the cause and how long the condition has been present. There may be increased tearing, squinting, or rubbing of the eye. There may be discharge from the eye that can vary from whitish to green. Your dog may avoid light, squint, or experience spasmodic blinking in bright light. The tissue around the eye may become swollen and red, and you may be able to see a divot in the surface of the eye. If the keratitis has been going on for a while, there may be blood vessels or pigment that develop in the area around the site of the corneal injury. There can also be fluid accumulation in the deeper tissues of the cornea, causing the cornea to become hazy.
What causes ulcerative keratitis?
There are many potential causes of ulcerative keratitis. These include:
- Trauma to the eye
- Inability to close the eyelids completely, exposing the eye surface to air, dust, and other irritants
- Diseases of the eyelids or tear-producing glands
- Abnormal tear production or tear quality
- Eye infections
- Primary diseases of the corneas
How is ulcerative keratitis treated?
Treatment depends on the cause of the keratitis, the length of time it has been present, and on the extent of damage that has happened to the cornea.
Most dogs with superficial corneal injury do not require surgery once the underlying problem is removed or resolved. Antibiotic ointment or drops will be prescribed, and it is important to prevent additional trauma to the cornea by removing excess hair around the eyes or using an Elizabethan collar (an E-collar or cone) for a short time. Ointments stay on the eye longer, so they are typically applied less frequently than eye drops. There may be multiple medications prescribed, depending upon the cause of the corneal damage.
Dogs with very deep ulcers may need to be hospitalized for frequent treatments or even surgery. Surgery may be as simple as removing loose surface cells once the surface of the eye is anaesthetized. This is called corneal debridement. Some corneal ulcers need to be repaired by a board-certified ophthalmologist. A contact lens may be placed on the eye for 1 to 2 weeks to act as a bandage.
It is important to restrict activity until the eye is healed.
What can I expect in the long-term for my dog’s eyes?
For a superficial corneal ulcer, the fluorescein stain will be repeated to confirm healing. If the ulcer is still present, it may signal the need for additional diagnostics and more aggressive treatment. If surgery is required, assessments will be more frequent, and the progress of healing will be followed very carefully.
Preventing recurrence of ulcerative keratitis may include applying lubricating ointment (artificial tears) or surgery to provide better closure of the eyelids. If your dog is diagnosed with dry eye, prescription ointments can help control the symptoms.
Superficial corneal ulcers typically heal within 5 to 7 days. Chronic ulcerative keratitis may require multiple treatments and may take weeks to heal. Deep corneal ulcers that require surgery generally require additional follow-up to prevent recurrence.
