In an interview, Dr. Nestle (pronounced NES-sel) said: “People are willing to spend anything on their pets. The $18-billion-a-year pet food industry is considered to be recession-proof. Although during this economic downturn shelters have been overwhelmed with pets people could not afford to keep, those who have kept their pets are not stinting on what they spend to feed them.”

Image Credit... Mike Bentley

She noted, however, that the so-called premium pet foods cost three to four times more than supermarket brands. Within the premium brands, there is also a wide price range, yet when the ingredients lists are compared, they are strikingly similar since all have to meet certain nutritional standards. The first five ingredients of nearly every kind of dog and cat food are generally the same, representing protein, fats and carbohydrates, Dr. Nestle said, adding that “anything listed below the salt would be present in only very small amounts.” She and Dr. Nesheim compared 10 premium chicken dinners for dogs and found that all contained basically the same ingredients: All start with chicken or chicken broth, followed by grains and vegetables. The nonpremium brands use more grains and poultry, meat and fish byproducts.

Most important, Drs. Nestle and Nesheim say, is to look for products labeled “complete and balanced,” indicating that they meet the nutritional requirements of cats and dogs listed by the Association of American Feed Control Officials. This organization, in conjunction with the Food and Drug Administration, state officials and the animal feed industry, develops model regulations for pet foods, which are voluntary unless encoded in state laws.

“All pet foods are made from the byproducts of human food production,” Dr. Nestle explained. “No matter what the package says, your dog is not getting whole chicken breasts, but what remains after the breasts have been removed for human food.”

And, indeed, it is primarily human food companies  Nestlé, Purina, Mars and Procter & Gamble  that make the pet foods sold throughout the world. Of course, in much of the world, domestic dogs and cats survive on table and street scraps, not commercially produced pet foods. In seeking evidence for the added value to health and longevity of commercial pet foods, the authors found almost none with any validity.

No agency requires proof of pet food health claims, and no pet food company is willing to invest in decades of research to determine whether its products keep animals healthier and extend their lives, the authors state. Pet food companies say they do research, but it is rarely done in a scientific fashion, with comparable control and experimental groups. There is, however, ample evidence that, despite claims to the contrary, both dogs and cats “are perfectly able to digest grains if they are cooked,” Dr. Nestle said.

None of this should imply that different pet food products make no difference to individual animals. When my friends’ havanese began licking its paws incessantly, the vet suggested they try a corn-free pet food, which stopped the itching. However, they need not spend $31 for a 12.5-pound bag of premium food free of corn; Costco’s Kirkland Super Premium Dog Food, also free of corn, costs about $15 for a 40-pound bag.