Usually conjunc. is fairly obvious bc there is increased discharge that, if not treated, it turns greenish and is sort of stinky - and their eyes irritate them (they'll sometimes paw at them, and/or they sometimes begin to lick/bite their paws). A corneal abrasion will result in a dog trying to keep the eye closed (and is VERY painful) and there is watering, but not necessarily discharge. The conjuctiva should be pink, but not red....
