Eye Ulcers, a Common Problem in Dogs & Cats

Pet Eyes and Ulcers—Ulcerative Keratitis In Dogs & Cats
The most common eye problem in dogs and cats is conjunctivitis, which is redness, swelling and pain of the thin membrane covering the eyes. The second most common problem is an ulcer of the cornea (ulcerative keratitis). It’s important to figure out whether the eye is simply inflamed or whether it actually has an ulcer because some medications used for simple conjunctivitis make ulcers worse.

What is an ulcer in the cornea?
The cornea is the first thing we see when we look into a dog’s eyes. The cornea is a clear, springy layer over the front of the eyeball that helps focus light on the retina at the back of the eye. Because we look right through the cornea and don’t see it, we tend not to appreciate it.

Cornea
The cornea is made of epithelial cells, rather like skin. The cornea has no blood vessels and receives its nourishment from the tears and fluids from within the eye. When the cornea is damaged and needs extra nourishment, blood vessels in the conjunctival membrane dilate to bring extra blood and oxygen. Although it doesn’t have its own blood vessels, the cornea does have nerve fibers and is extremely sensitive. Because of this sensitivity, corneal ulcers are very painful.

Conjunctiva
Over the cornea is another transparent layer, the conjunctiva. The conjunctiva is thin mucous membrane that covers the front of the eyeball and the inside of the eyelids. If a foreign body damages the cornea, it goes the conjunctiva first. The conjunctiva contains tiny blood vessels but the cornea has no blood vessels. Nourishment and oxygen moves from the conjunctiva to the cornea.

What causes eye ulcers?
The cornea can be scratched or ulcerated by dust, dirt, hair, eyelashes bacteria, , it develops an ulcer. The ulcer can be superficial and heal quickly, or it can be deep and heal very slowly. If the cornea is ulcerated all the way through, fluid (vitreous humor) from inside the eyeball leaks out and the eye can collapse. Whether ulcers are deep or shallow, they are exceptionally painful.

What you see if your dog has an eye ulcer
If you notice your dog squinting, blinking, or pawing at its eye, take a close look. If you see redness, swelling, increased tearing, thick discharge in the corner of the eye, or a pupil that doesn’t respond to light by dilating in the dark and constricting in the light, the cornea may be scratched and ulcerated. Visit your veterinarian immediately. On the way to the clinic, place a cool, damp tea bag on the eye, and if your pet is more comfortable, cover the eye to keep out the light.

Coming
In a future blog, we’ll look at which pets are predisposed to develop ulcers, how to prevent and treat them.