The driving force behind the increasing popularity of grain-free dog foods is mostly marketing and not based on actual research. Here are some common myths about grains in dog foods and the truth behind them.
Aren't grains poorly digestible?
Consumers are often told that grains such as wheat and corn are poorly digestible, and they should not be used in good-quality cat and dog foods. The truth is that the nutrients in grains are often readily available and absorbable to dogs.
Some prescription GI diets whose goal it is to be highly digestible will use grains such as rice and corn to deliver nutrients.
Aren't a lot of dogs allergic to grains?
There are very few reported cases of dietary intolerance or proven food allergy to corn in either cats or dogs.
Unlike corn, however, wheat and specifically wheat gluten can be a cause of food intolerance and hypersensitivity in dogs. It is estimated that about 5% of allergic dogs (not all dogs, just 5% of allergic dogs) are actually allergic to their food, and most are allergic to the animal protein (chicken, beef, pork, etc).
Beef, dairy and other protein sources are much more frequently implicated as causes of food allergies in dogs.
There is very little, if any, objective scientific evidence that shows corn is deleterious when used as an ingredient in commercial pet foods. The nutrients in corn are in fact readily utilized by the dog. While it cannot be used as the sole source of protein, it can be an important part of a balanced diet.
Corn is an excellent source of several important nutrients, including the essential fatty acid linoleic acid, as well as the carotenoids β-carotene and zeaxanthin.
Wheat is unique and particularly valuable amongst cultivated grains because of its high protein content. It is well utilized in dogs, and similarly to corn can be part of a nutritious diet.
Aren't grains just 'fillers'?
Studies show that dogs can thrive on plant based proteins in addition to animal based proteins in their diet. Dogs are not obligate carnivores, they are omnivores, meaning they eat a little of everything.
Grains, including corn, wheat, rice, barley, oats, sorghum, millet, rye, and others can all be a nutritious part of a well balanced diet. They can contribute not only as a protein source, but can also provide essential nutrients such as fatty acids.
Ok, you convinced me... Are grain-free diets bad then?
Studies providing clear evidence that grain-free cat and dog foods are better are lacking, but this does not necessarily mean you should avoid a good-quality pet food that also happens to be grain-free.
As long as the diet is a good quality, proven complete and balanced dog food with either detailed chemical analysis or feeding trials, then it doesn't really matter.
The primary contraindication to the use of grain-free foods in cats and dogs is probably the fact that these diets tend to be relatively high in both fat and protein. High fat content means more calories which can predispose to obesity in some animals.
High protein intake is contraindicated in animals with significant preexisting renal or hepatic dysfunction. Furthermore, when protein intake is higher than the actual requirement, the extra protein will simply be stored as body fat.
The best dog food for your dog is the one that keeps your dog the healthiest, with shiny coat and normal stools and minimal flatulence.