Contrary to popular belief, dogs are not carnivores. They are omnivores, animals that eat animal and plant protein. The misconception that dogs are carnivores and eat only animal flesh probably comes from the fact that dogs in the wild feed on their prey - other animals. However, their prey are herbivores who eat only plants. When wild dogs kill and eat their prey (caribou, deer, elk, rabbit, etc.), they rip into and eat the intestinal tract first. The intestinal tract is full of partially digested grasses, leaves and other plants.

In addition, wild dogs routinely consume grasses, berries, roots and other vegetable matter. The gastrointestinal physiology of dogs is fully capable of digesting and absorbing plant protein sources as well as meat protein sources.

Many myths exist surrounding the sources of animal protein and plant protein, such as soy, in dry dog foods. The quality of protein in complete and balanced pet foods depends on the right combination of essential amino acids and the digestibility of the protein. Following are a few explanations as to why certain sources of protein are used in dry dog foods: