Dog Food Myth-Busting

The truth about the seven most common dog-food myths and misconceptions


When you consider the bitter disagreements among human nutrition experts about the value of or harm from various types of diets – vegan, vegetarian, raw, ketogenic, gluten-free, paleo, organic, you name it! – it’s not surprising that there are so many myths and misconceptions about what we should feed our dogs. Not surprising, but disappointing. At least humans can choose their own diets; dogs depend on us to sort out the wheat from the chaff, so to speak. So let’s bust some myths!

MYTH 1: All “complete and balanced” dog foods that meet the nutritional levels established by the AAFCO Nutrient Profiles offer the same amount of nutrition. 

TRUTH: This couldn’t be further from the truth. Not only are the amounts of macronutrients (protein, fat, fiber) in dog food wildly variable, the micronutrient levels are, too! 

In this country, the legal definition of “complete and balanced” is established by a nongovernmental advisory group, the Association of American Feed Control Officials (AAFCO), which publishes the requirements for complete and balanced canine diets in   tables called the “AAFCO Dog Food Nutrient Profiles.” AAFCO makes occasional adjustments to the nutrient levels in the tables as continuing studies in animal nutrition are conducted. 

Unlike the “recommended daily allowance” (RDA) model that guides human diets with target nutrient levels, the AAFCO Dog Food Nutrient Profiles consist only of minimum values for all the nutrients required by dogs and maximum values for just a few nutrients that can be toxic if consumed in excessive amounts. As long as a food meets the minimum nutrient values expressed in the profiles, and doesn’t exceed the maximum values, it can be labeled as complete and balanced. 

That’s why it’s possible to compare two dog foods, both labeled as complete and balanced, and discover that Food A has twice as much fat or protein as Food B, or half as much iron or zinc.

The truth is, it can take a little (or a lot) of trial and error to find foods that will fully support your dog’s health. 

MYTH 2: “AAFCO Feeding Trials” are the gold standard for proving a food’s nutritional quality. 

TRUTH: Actually, it’s quite possible for foods that have passed an AAFCO feeding trial to contain insufficient or excessive nutrient levels; if a food passes an AAFCO feeding trial, it doesn’t have to meet the AAFCO Nutrient Profiles criteria. 

Feeding trials establish whether a food can sustain dogs for six months (at the most), which means the food may fail to maintain a dog’s health for years on end. Also, nutrient levels that depart dramatically from established minimum and/or maximum requirements for dogs can take a lot longer than six months to have deleterious effects on a dog’s health. 

A true gold standard for proving the nutritional adequacy of a dog food would be something that combined both of the existing qualifiers. Doesn’t it seem like a food should have to meet the minimum and maximum nutrient levels established by AAFCO and pass a feeding trial to ensure that the food was palatable and digestible? Sigh. 

MYTH 3: The best dog food is [insert the name of your favorite brand here]. 

TRUTH: We don’t care what brand name you insert in that myth; you’re wrong. There is no “best” food for all dogs, any more than there is a best food for all humans. 

All dogs are individuals, just like all humans. While there are many of us humans who can live perfectly well on a diet of fast food and highly processed frozen and prepared foods, some of us would die on such a diet. Some people can’t eat certain ingredients – or foods that contain gluten or foods with high amounts of fat – without suffering serious consequences. 

Well, it’s the same with dogs. Some can eat anything without ill effects, while others have highly sensitive digestive tracts that are in constant revolt. While we are eager to inform you about the traits of better-quality diets from reputable companies, our goal is to give you good options to choose from. You have to find what works best for your individual dogs. 

Myth 4: Once you find a food that suits your dog, you shouldn’t switch. 

TRUTH: You know who benefits the most from this myth? The pet food company who captured the money you spent on food when you first got your dog. 

It’s true that if you feed your dog the same food for months (or years) on end and then you change that food, he will likely display some digestive upset. That doesn’t mean you shouldn’t change his food; it means you should change his food more often!

Dogs have evolved with extremely efficient and flexible digestive abilities – and for the past few thousand years, they’ve been eating our leftovers, whatever that may be. They thrive on variety, just like we do. And the more variety there is in their diet, the more robust their digestion becomes. 

We strongly encourage owners to rotate among at least three different products from different pet food companies throughout the year. And more may be better! Why? Think back to Myth 1: No two foods contain the same macronutrient and micronutrient levels, and who is to say which ones have too much of this or too little of that for your dog? 

Most pet food companies use the same vitamin/mineral premix for all of their dry dog foods, but the nutrient levels in the premix used by one company will undoubtedly be different than those in the premix used by other companies. If you feed only one food, or even several products from just one company, you are entrenching those nutrient levels in your dog’s body. Rotating among a few products (made by different companies) can supply nutritional balance over time. 

The exception to this recommendation? Dogs who have proven to be intolerant of any change or allergic to a number of ingredients. 

Myth 5: The more the food costs, the better it is. 

TRUTH: The inverse of this statement is for sure true – the cheaper a food, the lower its quality – but because there are so many factors that affect pricing, the original statement is false. 

Some companies spend much more money on marketing than other companies who make similar foods. Gigantic companies have an advantage in the economy of the scale of their ingredient purchasing and manufacturing costs, but may spend a ton on research and  development. There are just too many factors involved to make a straight correlation between a high price and quality.

We don’t think you have to buy the most expensive food in the store in order to properly nourish your dog – but you definitely should not buy bargain basement food. The first five ingredients of the food pictured here are: Corn, meat and bone meal, corn gluten meal, animal fat, and soybean meal. Blech.

One thing you can do is to compare the price per pound of products with similar ingredients and macronutrient levels. There are relative bargains to be had among good foods. Just don’t go looking for bargain-basement foods; rest assured that they will not meet our selection criteria.

Myth 6: You should ask your veterinarian what food is best. 

TRUTH: We wish with all of our hearts that this myth was true, but the harsh fact is, few veterinarians know that much about nutrition or are willing to discuss any foods except the ones they sell.

Don’t get us wrong: We respect and appreciate veterinarians, and we’re not accusing them of a profit motive here. In most cases, we suspect it’s a matter of familiarity and a limited amount of available bandwidth. As you already are aware, there are way too many products to choose from. Once a busy practitioner is convinced of the quality of particular pet food company’s products, whether because of a talented salesperson or an informative seminar she attended, she’ll tend to recommend those foods and eschew discussion of the rest.

The lure of “prescription” diets that have been developed to address medical conditions can’t be overstated. If you were a veterinarian who was already putting in 12-hour days and barely keeping up with the workload, would you rather have a 30-minute talk with a client about diets with lower magnesium, sodium, calcium, phosphorus, and fat, which are supposed to be beneficial for her dog’s urinary tract health, or just recommend a prescription diet (conveniently carried by your clinic) that has those features?

Not all vets are that interested in or knowledgeable about food. It’s always worth asking them what food they’d recommend for your dog and why. But if their only suggestion is the food sold in the clinic and there isn’t a compelling reason for that particular choice, with respect, we’d take the advice with a grain of salt.

Myth 7: Corn is poison for dogs! No, wait! It’s wheat. And soy! 

A 27.5 pound bag of this prescription food, recommended by many veterinarians for dogs who are prone to any sort of urinary problem, costs around $90. Its first five ingredients are: Corn, chicken meal, pork fat, corn gluten meal, soybean mill run. (The legal definition of that last ingredient is “soybean hulls and such bean meats that adhere to the hulls which result from normal milling operations in the production of dehulled soybean meal”.). That’s crazy!

Truth: If any one of these food ingredients were one-tenth as bad for dogs as people say (allergenic! indigestible!), we’d have a lot fewer dogs today. All of those ingredients have been fed to dogs for decades. 

Like most myths, though, there are fine grains of partial truths behind these allegations.

Corn, and to a lesser extent, wheat, rice, and millet are prone to Aspergillus fungal infections. Aspergillus produces a highly dangerous substance called aflatoxin, which is not only a carcinogen but also can cause deadly liver damage in dogs. Pet food manufacturers that use these ingredients, especially corn, must be scrupulous about testing these ingredients as they come into their manufacturing sites and after the pet food is made.

Soy is denigrated as an ingredient in dog food for other reasons. It’s been alleged to cause allergic reactions, reduce the digestibility of protein, cause gas and diarrhea, and interfere with the absorption of minerals like calcium and iron. 

When used in pet food in minor amounts – and with proper quality control and ingredient testing – none of these or many other frequently impugned ingredients should be problematic for most dogs. Half a century ago, corn and wheat, in particular, were used in such high concentrations in dog food that it was almost inevitable that dogs who lived their whole lifetimes on these foods would be inadequately nourished. (We’re approaching a similar heavy usage/overreliance on peas and other of legumes in pet food today.)

Remember: If you change brands and formulas frequently, none of them should have an opportunity to cause long-term harm. 

Of course, if your dog has an adverse response to any food, stop feeding it. Give him a different food until his symptoms resolve, then try it once more. If the problem recurs, or if it causes a similar reaction in more than one of your dogs, see if you can return it. Ask your retailer to report the issue to the manufacturer, or contact the manufacturer yourself. Note the ingredients on a calendar or your dog’s health journal so you can try to identify a pattern of problems that you can link to certain ingredients or brands of food. 

Nancy Kerns is the editor of WDJ. 

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  1. Interesting article and I appreciate you explaining how corn in and of itself is not an issue but the handling in the safety of the ingredient batch etc. however I am curious to know like many articles I read a very subjects statements such as yours about veterinarians knowing nutrition. You wrote that veterinarians do not really know much about nutrition for dogs and just left it at that. I would like to know what basis that statement was made? It sounds more like an opinion than fact. You also wrote in so many words home veterinarians would rather just recommend one of their prescription foods etc. and explain and the nutritional needs for your dog or cat. I like many others have a veterinarian (along with the other 10 vets at the practice) that didn’t take the time to explain why a certain prescribed food or such will help with a UTI infection or kidney issues etc., of a dog or cat. So that’s my only beef with your article no pun intended. Lol. Ie, more so the statement you made that most of us don’t know about nutrition for dogs.

  2. Feed raw. Commercial dog food is garbage. Up until the mid 20th century, dogs ate human-grade food scraps. Then big name food companies saw the profit to be made from processed grains and meat by-products. Look up “extrusion,” the process by which dog food is made. My dogs eat fresh human-grade meat and bones from the grocery store, plus eggs, yogurt, fish oil and probiotics. Balanced, easy, and inexpensive compared to the cost of commercial food and vet visits for allergies, dental cleaning, skin and digestive issues. I’ve been feeding this way for more than twenty years and the health and condition of my dogs speaks for itself.

    • Yup! I agree completely. My dog is on raw 80/10/10`and doing great: she is ripped with muscle, she is energetic and healthy. A recent physical confirmed all this.
      On a side note, I have discussed raw diets with three vets and was surprised how little they actually know about nutrition and nutrition is the foundation of good health.

  3. I am concerned that some foods on your list contain copper sulfate, which from articles i have read can be toxic. Apparently the less synthetic copper proteinate or chelated copper is better. So why are the copper sulfate brands included?

  4. I did feed raw but now my dog is a senior and has some health issues (of course the vet prescribed prescription food for and said she had no real nutritional knowledge other than what she was taught by Hills) I cook his food (I researched how to do it correctly) and he is doing great (55lb 15yo).

    • I am very interested in giving my 8 yr old female chihuahua good food, and would like to know if you follow a recipe / guidelines for your cooked food? Her teeth have suffered from her previous diet and as a result (along with hereditary factors perhaps?) she has no front upper and lower teeth and only 15 overall remaining 🙁
      Thank you in advance for any information.

    • Protein from meat and eggs is best, protein from grains and legumes is not. When I started raw my dogs aggression almost disappeared, training and lack of carbs! Carbs for dogs is giving a hyper kids candy.

  5. Remember too, that both cereals (grass seeds like wheat/corn/rye) and pulses (legume seeds like peas, beans and lentils) have what is called ‘incomplete proteins’ – neither category provides all the protein needed by ‘carnivores’. Is is better to consume these seeds in a mix so that more protein is digested and absorbed by the consumer, rather than just making a richer urine.

  6. We have a dog with a very touchy tummy. We tried Science Diet and Fat Dog among many many others and found only 2 makers that his tummy did not rebel against. We switch flavors among the one maker because they offer food with wild game protein which our Veterinarian recommended. He’s a little overweight but healthy and active.
    Because of the sensitivity issue we are very hesitant to change between maker companies.

  7. I have had veterinarians tell me that they were required to take at least one course in nutrition in school and considered themselves well educated in canine nutrition. On what do you base your statement “few veterinarians know that much about nutrition?”

    • Because” at least one course” is not enough. Most only have one course, as that is all that is required in their education. Speak to a Veterinary Nutritionist. They are vets with a significant amount of additional training in nutrition. That’s who you should speak to if you have nutrition questions about dog food in this crazy marketplace. Here’s an example: Our vet was purchased by VCA and suddenly all the vets there were pushing Royal Canin. A little research on our part found that both VCA and Royal Canin are owned by the same corporation–M&M/Mars. Our puppy was having diarrhea issues and the vet kept blaming the food we were feeding her. I kept asking them to deworm her and they just said to feed her probiotics and their Royal Canin specialist diet. Guess what? It didn’t work. She’d be better then get worse again. Finally, one of the older vets saw us and immediately dewormed her. She recovered with no issues. Speaking to a veterinary nutritionist helped us confirm that the food we were feeding was FINE and that we shouldn’t trust the vet’s food recommendations. I absolutely trust my vet for surgery, immunizations, etc. Just not for her feeding.

    • At least at the turn of the century, the only ‘canine nutrition’ course run here for vet students was run by a Dog Food manufacturer 🙁
      Lookin at the food that the Vat sticks I doubt it has got much better.