Pet Nutrition Myths That Persist Despite the Evidence

The appeal of grain-free food is understandable — grains can sound like cheap fillers, and "ancestral diet" marketing is persuasive. However, dogs are not obligate carnivores, and grains like rice, oats, and barley are digestible, nutritious ingredients that have been safely used in commercial pet food for decades.

Beginning around 2018, the U.S. Food and Drug Administration (FDA) began investigating a potential link between grain-free diets — particularly those high in legumes like peas and lentils — and an increased incidence of DCM in breeds not typically predisposed to the condition. Research is ongoing and the mechanism is not yet fully established, but veterinary cardiologists have urged caution. Our in-depth piece on grain-free diets for dogs covers the science in detail.

Proponents of raw feeding argue that uncooked meat, bones, and organs mirror what animals ate before domestication. The veterinary consensus, however, is more cautious. Studies have found raw pet foods commonly contaminated with pathogens including Salmonella, Listeria, and E. coli — posing a risk not just to pets but to the people and other animals in the household, particularly those who are immunocompromised.

Nutritional balance is also a concern. Many raw diets — whether commercially prepared or home-assembled — contain inappropriate calcium-to-phosphorus ratios, inadequate vitamins, or excessive levels of certain minerals. Whole bones present choking and intestinal perforation risks. For a thorough look at the evidence, see our article on raw food diets for pets.

Cooking for a pet feels like a loving, transparent choice. The problem is that meeting all of a dog's or cat's micronutrient requirements at home is genuinely difficult without professional guidance. Research has found that the majority of homemade dog food recipes available online or in popular books are deficient in at least one essential nutrient — and often several.

Long-term nutritional gaps can lead to conditions like hypocalcemia, vitamin D deficiency, or imbalanced omega fatty acid ratios, depending on what the recipe lacks. If you're committed to home-prepared meals, working with a board-certified veterinary nutritionist to formulate a balanced recipe is strongly recommended. Our article on nutritional gaps in homemade pet food outlines what most recipes miss.

The word "by-product" triggers alarm for many owners, but the term has a precise regulatory meaning. AAFCO defines meat by-products as the non-rendered, clean parts of slaughtered animals other than meat — including organs like liver, kidney, and spleen, which are actually among the most nutritionally concentrated parts of an animal.

The relevant distinction is between named by-products (e.g., "chicken by-products") and unnamed or generic ones. Named sources are tracked and regulated; quality concerns are more legitimate with unspecified origins. For a fuller breakdown, our piece on protein sources in pet food explains how different ingredients function in your pet's diet.

Unlike dogs, who have some metabolic flexibility, cats cannot synthesize several essential nutrients from plant precursors. Taurine deficiency in cats causes dilated cardiomyopathy and retinal degeneration — conditions that were actually common before the pet food industry made taurine supplementation standard in commercial cat food. Arachidonic acid and retinol (preformed vitamin A) are similarly non-negotiable for feline health and must come from animal sources.

Plant-based diets for cats, even when supplemented, carry a meaningful risk of falling short on these nutrients. This is an area where veterinary consensus is clear: cats require animal-based nutrition to remain healthy. Always consult a veterinarian before considering any non-standard diet for a cat.