Updated October 13, 2026. Fact-checked against veterinary sources; review by a licensed veterinarian is in progress. See our editorial policy.
Quick answer: Red, goopy eyes in dogs have many causes. True bacterial eye infections are less common than people think. Frequent causes include allergies, dry eye (KCS), corneal ulcers, eyelid problems, foreign bodies, and blocked tear ducts, and serious conditions like glaucoma and uveitis can also cause red eyes. Because treatments differ and some causes threaten vision, eye problems should be checked by a vet.
Common causes
- Conjunctivitis: inflammation of the pink tissue around the eye, from allergies, irritants, or infection
- Dry eye (keratoconjunctivitis sicca): thick, sticky discharge from low tear production
- Corneal ulcers: scratches on the eye surface, causing squinting and tearing
- Eyelid problems: inward-rolling lids (entropion) or abnormal eyelashes
- Foreign bodies: grass seeds or debris
- Blocked tear ducts: see dacryocystitis
- Cherry eye: a prolapsed third-eyelid gland
Serious causes of a red eye
- Glaucoma: high pressure in the eye, painful, can cause blindness quickly
- Uveitis: inflammation inside the eye
- Injuries
When to see a vet
See your vet for any eye discharge lasting more than a day. Go the same day for squinting, cloudiness, a bulging eye, or sudden vision loss.
What to avoid
- Human eye drops and leftover medications, especially steroid drops
- Tea or homemade washes
Sources
- Merck Veterinary Manual: Conjunctivitis in dogs
- Merck Veterinary Manual: Corneal ulcers in small animals
- American College of Veterinary Ophthalmologists (ACVO): Pet owner information
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.