Veterinarians say that’s a matter of personal choice. Any pet food labeled as “complete and balanced” should meet your dog’s nutritional needs.
Liver, which is a byproduct, is rich in nutrients such as vitamin A. Meat byproducts also can contain blood, bone, brains, stomachs, udders, and cleaned intestines, according to the Association of American Feed Control Officials. Byproducts don't include hair, horns, teeth, and hooves, although an exception is allowed for amounts that occur unavoidably during processing.
Meat meal also may contain animal parts that many people consider to be byproducts. An ingredient listed as “chicken” or “beef” may include the heart, esophagus, tongue, and diaphragm. Although all these ingredients may sound unpalatable to you, your dog would probably disagree. So don’t necessarily balk if you see byproducts in the ingredients list.
Federal rules to guard against the spread of bovine spongiform encephalopathy (mad cow disease) ban some previously allowed cattle and buffalo parts in animal feed, including pet food. The FDA rule bans the inclusion of body parts from any animal that has tested positive for mad cow disease, as well as brains and spinal cords from older animals, as these are considered to be at higher risk of the disease.
Preservatives, artificial colors, and stabilizers in pet food must be either approved by the FDA or be generally recognized as safe, a category that includes everything from high fructose corn syrup to benzoyl peroxide, used to bleach flours and cheese. Manufacturers must list the preservatives they add, but they do not always list preservatives in ingredients such as fish meal or chicken that are processed elsewhere.
Some pet owners don't want to buy food that contains the synthetic preservatives BHA (butylated hydroxyanisole), BHT (butylated hydroxytoluene), or ethoxyquin. These preservatives stop fats from turning rancid and can keep dry dog food fresh for about a year, but their safety has been questioned by some consumers and scientists. But the FDA says they’re safe at the level used in dog food.
“There is a debate about whether there is a need to avoid artificial ingredients like these, as conventional safety testing says they’re fine,” says Susan Wynn, DVM, AHG, a nutritionist for Georgia Veterinary Specialists in the Atlanta area and a clinical resident in small animal nutrition with the University of Tennessee College of Veterinary Medicine. “I wouldn’t want them in my diet every day though, and I try to avoid them in my dog’s daily diet.”
Ethoxyquin came under scrutiny in the 1990s after complaints of skin allergies, reproductive problems, cancer, and organ failure in some dogs given food with this preservative. In 1997, the FDA asked dog food makers to halve the maximum allowed amount of ethoxyquin after tests conducted by manufacturer Monsanto Company showed possible liver damage in dogs fed high levels of the preservative.
Some manufacturers no longer use ethoxyquin, BHA, or BHT, instead using natural preservatives such as vitamin E (mixed tocopherols), vitamin C (ascorbic acid), and extracts of various plants, such as rosemary. Those also keep food fresh, but for a shorter period. Be sure to check a food’s “best by” date on the label before buying or feeding it to your pet.
“If you want shelf life, it’s better to have chemical preservatives,” says Joseph Wakshlag, DVM, PhD, assistant professor of clinical nutrition at Cornell University College of Veterinary Medicine. “They’re added at amounts that won’t harm the dog, and it creates a more stable fat. Rancid fat can cause liver enzymes to go up, and diarrhea.”
Look for a statement of nutritional adequacy on the label.
Many pet food makers follow model regulations set by the Association of American Feed Control Officials (AAFCO) that establish the minimum amount of nutrients needed to provide a complete and balanced diet. The statement may say the food is formulated to meet AAFCO standards or that it has been tested in feeding trials and found to provide complete nutrition.
The AAFCO statement also should say what life stage the food is appropriate for. For puppies, look for a food suitable for growth or all life stages. For adult dogs, look for adult maintenance or all life stages. Nutritional needs for senior dogs can vary, depending on health conditions, and there is no AAFCO standard for senior food.
All dog food labels must list the minimum amount of protein and fat in the food and the maximum percentage of fiber and moisture.
Some dog food labels also list the percentage of other ingredients, such as calcium and phosphorous.
Low-fat dog foods often contain less fat and more fiber, to fill up a dog without adding calories.
At least 10% of the daily diet, by weight, should be protein, and 5.5% should be fat, according to the National Research Council, a scientific research unit of the nonprofit National Academies. Dog foods typically contain higher amounts than those, because dogs may not be able to digest all of the nutrients in a food.
Legally, not much. Food labeled as natural should contain few, if any, synthetic ingredients. Holistic, along with premium and super-premium, are marketing terms and there is no rule that controls how they’re used. Watch out for marketing terms like “human-grade ingredients” or “made in a USDA-inspected facility,” too.
“It’s difficult to confirm those claims are truly accurate,” says Teresa Crenshaw, interim chair of AAFCO’s pet food committee. Although pet food can be made in a USDA-inspected plant, it may happen when there is no inspector present, Crenshaw says. Meat once considered safe for humans may have spoiled and been diverted to pet food, she says. Neither claim means the food is safe for humans to eat.