Why Does My Dog Have Eye Discharge?

Some amount of eye discharge in dogs is normal — tears constantly lubricate the eye and small amounts collect in the corners. The key is distinguishing normal discharge from signs of a problem.

Clear, watery discharge (epiphora) is the most common and least concerning type. It's usually caused by allergies, wind, dust, or minor irritation. Some breeds (especially brachycephalic breeds with shallow eye sockets and breeds with prominent eyes) produce excess tears as a normal variation.

Reddish-brown tear staining (most visible on light-colored dogs) is caused by porphyrins — pigments in tears that oxidize and discolor the fur. This is usually cosmetic rather than medical, though excessive tearing should be evaluated to rule out blocked tear ducts, eyelid problems, or irritation.

Yellow or green discharge is the primary concern. This indicates infection — bacterial conjunctivitis, corneal ulcer, or internal eye disease. It often comes with redness, swelling, squinting, or rubbing at the eye. Thick, crusty discharge that seals the eye shut overnight also warrants a vet visit.

A sudden onset of squinting with watery discharge can indicate a corneal scratch or ulcer — especially if your dog was playing in brush, had a run-in with a cat, or was pawing at their eye. Corneal ulcers are painful and can worsen quickly without treatment.