What if I told you that I had manufactured a food that contained everything you needed to keep you healthy and all you had to do to prepare this wonder food would be to open a tin or packet and pour it out? You would know that it couldn't possibly be true because we all accept that for people to be truly healthy we have to eat a variety of fresh foods, foods that contain the nutrients we need in their natural, unprocessed form. Yet we are prepared to believe that dogs ...