Red, runny eyes are a common veterinary problem that often signals a respiratory infection or minor irritation. On occasion, the problem goes deeper.

A corneal ulcer is a pitting of the thin, transparent layer of tissue that forms the front part of the eyeball. Causes include eye infection, dry eye, and trauma from scratches or foreign bodies such as splinters. Dogs and cats with “pushed-in” faces and bulging eyes, such as pugs, are especially at risk.

Corneal ulcers are very painful and, left untreated, could lead to vision problems from scarring that darkens the cornea.

When your veterinarian performs an eye exam, a special dye called fluorescein is used to outline the ulcer in a bright greenish or orangish color. With proper treatment, including antibiotic eye drops, uncomplicated ulcers usually heal rapidly without permanent effects.