1) What is the best diet? There is no one best diet for dogs. Individual dogs, like individual people, digest food differently. Your dog should be fed a diet that is balanced and, if it is a commercial diet, approved by the Association of American Feed Control Officials (AAFCO) for the stage of life your dog is in (e.g., growing, maintenance, performance). I consider easy maintenance of correct body weight, normal feces, normal activity, and normal hair coat as evidence...