Zealotry about pet food is every bit as self-satisfied as a Food Babe mantra. Since food is the new religion, and pets are the new kids, the new angels and demons must be different ingredients in pet foods. Ask a chihuahua owner in the pet store why they’re reaching for a $40 bag of kibble with a painting of a wolf eating a caribou, and they’ll usually say, “Because it’s biologically appropriate“. As the joke goes, I’ve never seen a pack of chihuahuas hunting caribou (the closest I’ve seen is a Chihuahua wearing a reindeer outfit). But let’s just say for sake of argument that Paleo for poodles were better for dogs (it’s not). If that were true (and again, it’s not), can you wriggle your self-righteous nose knowing that you’ve given Mrs. Fluffybutt the finest tundra ungulate* meat available?

Well no, and not just because your premise is wrong.

The problem is a little-talked-about issue in pet food known as mislabeling. Mislabeling means the contents of the food are different from what is stated on the label. It can be either added ingredients that aren’t listed, or listed ingredients that aren’t added. It’s rampant in pet food, and despite being pervasive, it’s a largely ignored issue in the greater fanaticism about what our pets eat. Mislabeling is just one problem in pet food, which is about as full of myths as the Greek pantheon. We’ll get to mislabeling in a bit…

But first, let’s all freak out about pet food

If you want to test the limits of your sanity, walk into a boutique pet store and ask the kind-hearted attendant what you should feed your Norwegian puffinhund. There is a great deal of public confusion about what pets should be eating. We’ve seen a completely unnecessary “grain free” movement that now may be responsible for making hundreds of pets sick. And thousands if not millions of pet owners feed their pets raw meat in a misguided belief that they are doing them a favor. Many if not most of these people are well-intentioned but misinformed, but then of course there are all sorts of scams taking advantage of these fears, including a cringe-worthy Netflix “documentary”, and bogus food allergy kits marketed to pet owners.

This is all exhaustingly familiar to skeptical eaters of food, who know that most fear-mongering about most foods is ignorant bunk at best, and profit-motivated deception at worst. There are strong incentives in the pet food industry to hype their food, with annual sales of pet food in the US at about $30 billion, and over 600 brands (not types or formulas but brands) of pet food all competing with each other for your dollar. At the same time, the size of a bag of pet food is getting smaller, so we’re spending more money on smaller, more customized pet foods. People are paying a premium to get what they believe are superior ingredients. Even if they don’t need it (and again, they don’t), at least what’s on the label should be what’s in the bag, right?

The (actual) truth about what’s in pet food

Now let’s get back to mislabeling. You might be surprised to find out that the ingredient list on a bag of pet food is not a sacrosanct document verifying the precise contents of that particular bag. However, there are a number of studies looking at the discrepancy between food labeling and actual contents (reviewed nicely here). Of the nearly 800 foods investigated in this review, about 45% tested positive for unlabeled ingredients, with some studies showing rates as high as 83%. Most of these cases were of unlabeled added ingredients, but a significant number of them couldn’t find a labeled ingredient in the food! What’s more, most of these tests used PCR, which only works when you know exactly what you’re looking for,** so it’s probable that the actual percentage of mislabeled foods is much higher.

That is a decent sample of commercial pet foods and a shockingly high amount of mislabeling. Even with “limited ingredient” products, which are marketed to owners of pets who may have a sensitivity or allergy to certain foods, a recent study found that all the diets included had DNA from a source not listed on the ingredient list (and one diet didn’t even test positive for the listed ingredient!). And even in the diet that is considered the gold standard for dogs with dietary allergies (a hydrolysed protein diet) unlabeled proteins that could be allergens were detected.

It seems there’s a lot of “other” stuff in pet foods, although the amounts detected could have been trace and contaminants from using the same equipment to process different types of foods. In case you are smugly scoffing at the pet food manufacturers for being incompetent yokels, be aware that your own food supply is hardly better. Food mislabeling in human products is rampant as several high profile scandals (tahdah!) made clear.

Does any of this actually matter?

We don’t actually know how much of a problem this is. PCR is extremely sensitive, so the amount of mislabeled ingredients in pet food might not even cause clinical problems. But obviously there are issues of consumer protection and outright food fraud to contend with. I, for one, would be a bit miffed if I walked into a movie theater to watch Toy Story 4 and was instead shown Fifty Shades Freed, even if they’re equally as entertaining.

For some individuals though, mislabeled food can be a serious problem. Consider the warnings on food packages that state whether or not a product was processed on equipment that also processes nuts. The FDA regulates both human and pet food, and issues dozens of allergen-related food recalls each year. Fortunately, dogs and cats don’t often get severely ill from dietary allergens, but there are lots of pets that don’t tolerate some ingredients. For those of us and our pets without dietary allergies, it’s pretty unlikely that any of these ingredients are making us sick in any way.

Conclusion: Don’t quibble about kibble

Most pet food labeling is simply not very helpful. The front of the package labeling is often woefully misguiding, and most pet owners aren’t aware of what they should be looking for. There’s little guarantee that the ingredients listed are an accurate representation of the food in the bag, even though mislabeling pet food is a federal crime. Pet owners, like most people, think food is a lot more important to health than it is. But dogs are evolved from dumpster diving mongrels, and wolves in captivity do great on commercial dog food, so can we all agree that most pets are going to be fine on most foods (in fact they’ll eat almost anything), as long as they’re not overfed? No? We can’t agree? Okay, well then I guess I’ll just keep working on suppressing my sense of irony as English bulldog owners proudly tell me they would never give their dog a food that contains GMO’s. Sigh.

*Can we please, please call caribou tundrgulates?

**For example, nobody was looking for tree DNA, which may be making its way into pet food soon.



  • Greg Bishop is a veterinarian in Oregon who works mainly with dogs and cats. As a fan of the SBM blog, he sees the enormous amount of bad science and information in the field of veterinary medicine as an opportunity, not a problem! But also a problem.

Posted by Greg Bishop

Greg Bishop is a veterinarian in Oregon who works mainly with dogs and cats. As a fan of the SBM blog, he sees the enormous amount of bad science and information in the field of veterinary medicine as an opportunity, not a problem! But also a problem.