Pet Nutrition Myths That Many Owners Still Believe

The grain-free trend drew heavily from the idea that dogs and cats evolved eating meat, not grain. However, dogs have developed specific genetic adaptations for starch digestion compared to wolves, and grains such as brown rice and oats provide fiber, B vitamins, and energy. More critically, the U.S. Food and Drug Administration (FDA) investigated a potential link between grain-free diets high in legumes and dilated cardiomyopathy (DCM) — a life-threatening heart condition — in dogs. While causation has not been definitively established, veterinary cardiologists and the AVMA have urged caution. Pets with a confirmed grain allergy are the exception, but true grain allergies are far less common than marketing suggests.

Proponents argue that raw feeding mirrors ancestral diets, but multiple studies — including research cited by the American Veterinary Medical Association (AVMA) — have found raw meat diets frequently contaminated with pathogens such as Salmonella, Listeria, and E. coli. These bacteria can sicken pets and the people who handle their food, particularly young children, elderly individuals, and immunocompromised household members. Additionally, many homemade raw diets are nutritionally unbalanced. The AVMA and the American Animal Hospital Association (AAHA) both discourage raw or undercooked animal-source protein in pet diets due to these risks.

The word "by-product" triggers concern, but AAFCO defines meat by-products as the non-rendered, clean parts of slaughtered animals other than muscle meat — this includes organs such as lungs, spleen, kidneys, brain, liver, and blood. These tissues are nutritionally valuable, often richer in certain micronutrients than muscle meat alone. What by-products do not include, under AAFCO rules, is hair, hooves, horns, or manure. Knowing how these terms appear on labels helps put ingredient lists in context. See our article on decoding pet food labels for more detail.

Manufacturers print feeding guidelines based on average animals at typical activity levels. A senior, sedentary indoor cat needs significantly fewer calories than an active young adult of the same weight. Feeding the package amount without adjustment can lead to gradual weight gain over months or years. Veterinarians recommend using guidelines as a starting point, then monitoring body condition score — a hands-on assessment of fat coverage over the ribs — to calibrate intake. Our guide to pet weight management explains how body condition scoring works in practice.

Unlike dogs, who are omnivores with metabolic flexibility, cats lack key enzymatic pathways that would allow them to synthesize essential nutrients from plant precursors. Taurine deficiency in cats causes dilated cardiomyopathy and retinal degeneration. Arachidonic acid and preformed vitamin A must come from animal tissues. While some commercial vegan cat diets add synthetic versions of these nutrients, the long-term safety and bioavailability of plant-based feline diets remain an area of ongoing veterinary concern. For cats specifically, animal-derived protein is not optional — it is physiologically necessary.