Grain Free Diets for Dogs

With the popularity of grain free diets for humans, the trend is now moving to veterinary medicine.  Are diets free of grain products better for dogs than diets with grain?  Well, it depends upon the individual dog.  Grain free diets are not inheritantly better just because they are grain free.  Let me explain.
Unlike cats, dogs can metabolize protein from plants as well as animals.  This is why dogs can be placed on a vegetarian diet.  Cats must consume animal protein to satisfy their nutritional needs.  Dogs with food allergies become allergic to a protein in their diet.  Whenever they consume the offending protein, it triggers a reaction which may include vomiting, diarrhea, ear infections, itching and impacted anal glands.  In my experience beef, corn and soy are the most common causes of food allergy.  Why?  Because they are common ingredients in dog food, dogs with allergic tendencies are exposed and develop allergies.  I have had several clients place their pets on lamb and rice diets to ‘prevent’ food allergies.  These dogs developed allergies just like the ones on beef and corn.  If a dog is allergic to a certain protein, whether it is animal or plant based, then it should obviously be excluded from the diet.  Since grains are such a large group, it is unlikely for one dog to be allergic to the entire group.  

Grain free diets for humans started because many people suffer from celiac disease which is basically an allergy to gluten, a protein found in many cereals.  Corn and rice are gluten free while wheat, barley, rye, oats and buckwheat contain gluten.  So far, gluten-sensitive enteropathy has only been documented as a hereditary disease in Irish Setters.  (Garden, O.A., et al., Inheritance of gluten-sensitive enteropathy in Irish Setters. Am. J. Vet. Res. 2000, Vol.61(4) pp.462-8.)

There are several problems associated with grain free diets that must be considered before use.  Many of these diets substitute potato or tapioca for grains.  Unfortunately, these two carbohydrate sources have a higher glycemic index that may cause problems in diabetic animals.  The more refined the carbohydrate, the more quickly it is absorbed into the blood stream causing a huge jump in blood glucose levels.  Most diets for diabetic dogs add fiber to slow absorption and blunt the post prandial glucose spike.  

My other concern with grain free diets is their composition.  Many substitute fat or protein for the missing carbohydrates.  Excessive energy levels in puppy food, especially large and giant breed puppies, may cause orthopedic problems from rapid growth.  Large and giant breed puppies should not be overweight.  The round, pudgy puppy might be cute but it is not good for their long term health.  Diets for dogs with kidney and liver dysfunction are also formulated with low to moderate protein levels.  Excessive dietary fat is a factor in dogs developing pancreatitis and diabetes mellitus.  In breeds prone to hyperlipidemia like miniature schnauzers, I would be very cautious about fat content.  Analyze the diet based on metabolizable energy (M.E.’s), not as feed or dry matter.  (See prior post on how to read a pet food label for further information on M.E.’s.) 

Who knew food could be so complicated?  It is why sometimes, your pet really does need a prescription diet.

Published by kristennelsondvm

Dr. Kristen Nelson grew up on a farm in Watertown, Minn., where she developed a deep love for animals of all kinds. She received a Doctor of Veterinary Medicine degree from the University of Minnesota, College of Veterinary Medicine. Kris then completed a small-animal internship at the prestigious Animal Medical Center in New York City. In addition to writing and speaking, she cares for small and exotic animals in Scottsdale, Az. Dr. Nelson is widely quoted in the media. Her credits include Ladies’ Home Journal, USA TODAY, the Los Angeles Times and numerous radio and television interviews. Dr. Nelson has written two books, Coated With Fur: A Vet’s Life and Coated With Fur: A Blind Cat’s Love. Kris and her husband Steve share their home with rescued cats, birds and a dog.