Pet Nutrition Myths That Persist Despite the Evidence

The appeal of raw feeding is intuitive — ancestors of our pets ate unprocessed meat, so raw food feels closer to nature. But domesticated dogs have co-evolved with humans over thousands of years, and their digestive systems and nutritional needs differ meaningfully from wild canids. More practically, studies have repeatedly detected pathogens including Salmonella, Listeria, and E. coli in commercially prepared raw pet foods, posing risks to both animals and the humans handling the food.

Nutritional imbalance is an equally serious concern. Many raw diets, particularly homemade ones, are deficient in key nutrients like calcium, phosphorus, and essential vitamins. Our overview of raw feeding for dogs and cats covers the evidence and what veterinary guidance currently recommends for owners considering this approach.

Grain-free pet food became enormously popular on the premise that grains were cheap fillers causing allergies and inflammation. The evidence doesn't support this for the average healthy pet. Dogs and cats digest cooked grains well, and grains contribute fiber, B vitamins, and energy. True grain allergies exist but are far less common than marketing suggests.

More significantly, the U.S. Food and Drug Administration (FDA) has investigated a potential link between grain-free diets high in legumes or potatoes and dilated cardiomyopathy (DCM) — a serious heart condition — in dogs. The research is ongoing and causality has not been firmly established, but major veterinary cardiology groups have recommended caution. If your dog has been eating grain-free food, this is a conversation worth having with your vet. For context on reading food labels and understanding ingredient terms, see our pet nutrition terms reference guide.

An occasional piece of plain chicken or a carrot is unlikely to harm a healthy dog. But the habit of sharing meals introduces real risks. Many common human foods — including onions, garlic, grapes, raisins, and anything sweetened with xylitol — are toxic to dogs and cats. Even non-toxic extras add calories that accumulate over time. Veterinary data consistently shows overfeeding and excess treats as leading contributors to pet obesity, which shortens lifespan and increases chronic disease risk.

If you notice your pet seeming low-energy, losing coat quality, or having digestive irregularities, it's worth reviewing both their main diet and what extras they're receiving. Our article on signs your pet's diet may not be meeting their needs can help you identify what to watch for.

The Association of American Feed Control Officials (AAFCO) sets nutritional standards that reputable commercial pet foods are formulated to meet. Foods bearing an AAFCO nutritional adequacy statement have either passed feeding trials or been verified to meet established nutrient profiles for a given life stage — a level of scrutiny that most homemade diets never receive.

Cooking for your pet is not inherently wrong, but meeting complete nutritional needs consistently is harder than it appears. Research on owner-formulated homemade diets has repeatedly found deficiencies in critical nutrients. If you're committed to home cooking, a board-certified veterinary nutritionist can help you formulate a diet that's actually complete. See our deeper look at nutritional gaps in homemade pet diets for a fuller picture.

Cats are obligate carnivores with specific physiological requirements that differ fundamentally from dogs. They require dietary taurine (an amino acid dogs can synthesize themselves), preformed arachidonic acid, and higher overall protein levels. Cat food is formulated to meet these needs; dog food is not. Feeding a cat dog food long-term can lead to serious deficiencies, including heart disease from taurine insufficiency. The reverse — feeding cats' food to dogs — is less dangerous but still inadvisable due to the higher fat and protein content. Our article on why swapping dog and cat food is a problem explains the species-specific science in plain language.