Grain free dog food. Grains have long been one of the most prevalent ingredients in dog foods of all kinds. Although dogs can digest, process, and make nutritional use of grains, some believe that dogs are less healthy when they regularly consume grains. Official, peer-reviewed studies have shown that dogs are not harmed by the consumption of grains. As a matter of fact, grains only pose issues to canines if they are known to have existing allergies to grains. Some dog owners think that grains even go as far as causing allergies, something that isn’t true at all. Dogs that are known to have digestion issues may be best served by eating grain-free dog foods, though virtually all other kinds of dogs, outside of those who have specific grain allergies, should regularly eat grains.