The easiest way to determine if a dog is blind is by consulting a veterinarian to examine the dog's eyes. Looking out for symptoms of blindness or gradual loss of vision can also help a dog owner recognize if a dog's vision is failing or has failed.
Gradual loss of vision in dogs is difficult to detect, though there are some telling signs that a dog has failing eyesight. One way to determine this is to observe the dog in a dark room. Rearrange the furniture and watch to see if the dog hesitates to move from one spot or bumps into structures or objects. Turn on the light and repeat the test. If the dog shows more confidence in a brightly lit room, it might have trouble seeing and moving in the dark. If, however, the dog still hesitates to move even with the lights turned on, chances are the dog is completely blind. A dog with failing vision may also be unable to find the food and water dishes and may get confused in new surroundings easily. A dog who is visually impaired may also show disorientation or confusion, become depressed or anxious or walk with its nose close to the ground. Physical signs of dog blindness are cloudy, inflamed, discolored and tearing eyes with dilated or enlarged pupils.