You are jamming to your favorite tunes as you cruise along the highway, when suddenly you hear the telltale “thud” of a piece of gravel bouncing off your windshield, taking out a chunk of glass. If you pretend your car is an eye, and the windshield is the cornea (i.e., the clear portion at the front of the eye), your eyeball/car would have a corneal ulcer/chip in the glass. Both must be addressed promptly—neglecting to fix a chipped windshield can lead to a spiderweb of cracks, and missing your pet’s corneal ulcer can cause significant pain or loss of vision. However, since this isn’t a car blog, we will stick to pets. Keep reading, to discover the answer to pet owners’ common questions about corneal ulcers.

Question: What is a corneal ulcer?

Answer: The cornea is composed of outer epithelial cell layers, a thick stroma, thin Descemet’s membrane, and inner endothelial cell layer, and a corneal ulcer is the disruption of one or more of these layers. Superficial ulcers involve injury to the epithelial layers only, while deep ulcers invade the stromal layer or, in severe cases, Descemet’s membrane. Once an ulcer reaches Descemet’s membrane, the eye is at high risk for rupturing, as this thin membrane and single cell-layer-thick endothelium are all that separate the eye’s inner contents from the outside world. 

Q: Why do pets get corneal ulcers?

A: Dogs and cats tend to get corneal ulcers for different reasons, with dogs more prone to traumatizing the eye, and cats more likely to have viral ulcers. The common causes of ulcers in dogs include:

  • Injury — Corneal ulcers may occur when a dog runs into plants or bushes, is hit in the face with an object, or gets scratched by another animal. 
  • Self trauma — Dogs who paw at their face, or rub it on the floor secondary to allergies or irritation, may traumatize their eyes.
  • Foreign material — Plant pieces, chemicals found in shampoo, or other foreign items can damage the cornea, leading to an ulcer. 
  • Other causes — Keratoconjunctivitis sicca (i.e., dry eye), abnormal eyelid conformation or eyelash location, or viral or bacterial infections are less common causes of corneal ulcers.

Cats get corneal ulcers for the following reasons:

  • Viral infections — Feline herpesvirus infection is the most common cause of corneal ulcers in cats. Infected cats may also have upper respiratory signs, such as sneezing and nasal discharge, and once infected, the virus will persist in the cat’s body for life. Periodically, the virus will multiply again, and cause signs to reoccur.
  • Additional causes — Injury, self trauma, foreign material, dry eye, or eyelid and eyelash abnormalities can cause ulcers as in dogs, although less commonly.

Q: What are corneal ulcer signs in pets?

A: Corneal ulcers are extremely painful, so affected pets will hold the eye closed, or squint, and may resist the eye being touched. The white portion of the eye is usually red, the cornea may look cloudy around the ulcerated area, and eye discharge can range from clear tears to yellowish-green mucus. If your pet is showing any of these abnormalities, and you suspect they may have a corneal ulcer, promptly contact Veterinary Vision Center, as ulcers that are not addressed quickly and correctly can worsen quickly, and cause long-term vision issues, or necessitate eye removal.

Q: How are corneal ulcers diagnosed in pets?

A: If we suspect a corneal ulcer, our Veterinary Vision Center team will apply several drops of fluorescein stain to your pet’s eye. The stain slides off normal areas of intact cornea, but will stick to any ulcerated areas, thus highlighting the ulcer’s size, location, and shape when illuminated with a blacklight. In some cases, our team will also examine the cornea cells under a microscope, or submit a culture and sensitivity test to determine the best choice of antibiotics.

Q: How are corneal ulcers treated in pets?

A: Our Veterinary Vision Center ophthalmologist will design a treatment plan for your pet based on the ulcer’s type, size, severity, and underlying cause. Superficial ulcers typically heal well in three to five days using topical antibiotics to address infection, pain medication to control inflammation and discomfort, and an E-collar to keep your pet from further traumatizing the eye. Cats with herpes ulcers may also be treated with antiviral medications. Ulcers that are deep or did not heal as expected may require various procedures, such as removing loose or damaged corneal epithelium, patching a deep ulcer, or repairing a ruptured eye using part of the conjunctiva (i.e., the mucous membrane on the front of the eye). 

If you suspect that your pet has a corneal ulcer, or are concerned because an existing ulcer is not healing as expected, immediately contact Veterinary Vision Center for an evaluation by our board-certified veterinary ophthalmologist. Let us use our expertise to ensure your pet’s corneal ulcer is treated correctly, and their vision restored pain-free.