Q. You said in a recent article that it’s not a good idea to choose dog food by the ingredients list because it doesn’t tell whether the food has the right nutrients in the right proportions. But I have always looked at the ingredients list before buying my dog food. For instance, one popular dog food lists corn and soybean hulls as the third and fourth ingredients. Why should those two plant foods be so high up on the list? Dogs are carnivores, not herbivores.
Dear Ms. Hite,
A. Dogs are not carnivores. They are omnivores, meaning that they can digest plant foods in addition to animal foods and can absorb nutrients from them. In fact, when researchers compared the dog genome to the wolf genome several years ago, one of the two major differences they found is that dogs are much better able to digest starch — a component of plant foods. (The other major difference was about behavior traits, which would explain why you wouldn’t think of a wolf and a Golden retriever as having similar temperaments.)
Corn, by the way, is a rich source of linoleic acid, an essential fatty acid that dogs must get in their diets. It also contributes vitamins and minerals, along with some of the fiber dogs require. In addition, corn is a good source of the phytonutrients lutein and zeaxanthin, which researchers believe have potential health benefits.
As for soy, it contains high-quality plant protein. Moreover, it is often recommended for dogs with food allergies, as well as for dogs with recurring bladder stones known as urate stones and also dogs with liver disease. And it’s a perfectly safe, nutritious ingredient even for dogs without any of those conditions.
Checking the Statement of Nutritional Adequacy on a food label remains the best way to go for assessing whether a food is right for your pet. A sentence from the Association of American Feed Control Officials (AAFCO) saying that a food is appropriate for “maintenance” or “all life stages” means it is an appropriate choice for a healthy adult dog.