We often hear our clients tell us that they wish to pursue a grain-free diet for their pet, because they have heard that cereals are “fillers”, that grains such as wheat cause food allergies, or that grains are bad for pets.
We believe that every ingredient in a pet food must have a nutritional purpose Cereal grains are ingredients that provide energy (in the form of starch), essential nutrients (essential fatty acids, vitamins, and minerals) and fibre. The carbs and proteins in grains add nutritional value and structure to pet food. Finally, in using grain protein for energy, protein from other sources can be used to build and maintain muscles and tissues.
Dogs and cats can digest cereal grains if they are properly cooked and as long as the overall diet is complete and balanced there is no evidence to show they are harmful. Some pets can develop allergies to grains, but meat sources are more likely to be the culprit. In any event, treatment of food allergies should be undertaken under veterinary advice to ensure a suitable food elimination trial identifies the correct cause.
Finally, many advocates of grain free diets take this position because they believe that meat should be the primary pet food ingredient often because they believe that a high protein diet is better. In fact, AAFCO require 18% protein in pet food diets. Excess protein can turn into fat, cause flatulence and runny/sticky stool. It is the quality of the protein that is important. Higher protein levels do not mean that the protein is digestible and is not automatically better for the pet.
DVM have an excellent article on grain free diets and particularly the association with dilated cardiomyopathy and is accessible here.