Conjunctivitis or pink eye is an inflammation of the membrane covering the back of the eyelid and the surface of the eye up til the cornea. There's usually a discharge. If both eyes are involved it could be an allergic reaction to something. When one eye is inflamed, it could be caused by a piece of dust or dirt, an eyelash or some other foreign body. You can try flushing the eye with a saline solution or artificial tears, both of which can be purchased at a pharmacy. In any case and especially if conjunctivitis is something that occurs often, your dog should be seen by the vet as soon as possible.
