What it is
The conjunctiva is the eye's first line of defence: it produces mucus which, together with the tears, traps dust and microbes. When irritated it turns red and swells, the eye starts to water, and the tears thicken into a mucus- or pus-like discharge.
It matters whether one eye is inflamed or both. When only one eye is affected, the cause is more likely to be local: a foreign body, a scratch, an inward-turned eyelid or a blocked tear duct. When both eyes are affected, allergy, dry eye, infection or a general illness are more likely. Conjunctivitis is easily confused with more serious eye diseases, such as a corneal ulcer or raised pressure inside the eye, which also cause red eyes.
In the car, don't let your dog put its head out of the window: wind, dust and insects irritate the eyes. If an eye turns red, don't put anything into it until a vet has examined it, least of all eye drops meant for people.
Signs you may notice
- Red eyes
- Watery eyes
- Mucus or pus discharge
- Squints the eye
- Rubs the eye with a paw or its face on furniture
The eye turns red and waters, mucus or pus collects, and the eyelids may swell and stick together. The dog squints, rubs the eye with a paw or rubs its face on furniture.
When to see a vet
Book a visit if an eye stays red and watery for more than a day, or a mucus or pus discharge comes from it. If your dog squints hard, the eye looks cloudy, is painful or has been injured, have it seen promptly.
This is general information, not veterinary advice. For your own dog's health, tests and treatment, see a vet.