» The Facts About Grain-Free Diets and Canine Dilated Cardiomyopathy: Part One – The Evidence (and How It Has Been Misinterpreted by Leading Veterinarians) - The Optimal Dog

The Facts About Grain-Free Diets and Canine Dilated Cardiomyopathy: Part One – The Evidence (and How It Has Been Misinterpreted by Leading Veterinarians)

The Facts About Grain-Free Diets and Canine Dilated Cardiomyopathy: Part One – The Evidence (and How It Has Been Misinterpreted by Leading Veterinarians)

In a way, this piece is a reaction to a press release issued by the Food and Drug Administration earlier this month informing pet owners that the organization had begun investigating a potential link between diet and canine dilated cardiomyopathy (DCM), an historically rare disease characterized by enlargement (dilation) of the heart muscles.

But, more specifically, it’s a reaction to the problematic way this news has been interpreted by a few leading veterinary experts. News of the FDA investigation was immediately seized upon and amplified by several of the country’s most visible veterinary nutritionists, including Dr. Lisa Weeth and Dr. Lisa Freeman. (The AVMA and several major international media platforms, including the New York Times, followed suit.) And, in every case of which I am aware, the take-home message was more or less the same—pet owners should view the FDA investigation as a reason to avoid “grain-free” pet foods.

In a blog post written just days after the FDA investigation was announced (entitled “In Defense of Grains”), Dr. Weeth characterized the investigation as being primarily about “grain-free pet foods.” And, in a Twitter post praising the FDA’s investigation, she warned her followers that “the grain-free #petfood trend may be doing more harm than good.”

Dr. Freeman went even further. On June 4, she published a lengthy article on a pet food blog linked to the Cummings Veterinary Medical Center at Tufts University, where she is a professor. The piece was entitled “A Broken Heart: Risk of Heart Disease in Boutique or Grain-Free Diets and Exotic Ingredients.” In it, she affirmatively advised pet owners currently feeding “grain-free” pet foods to “reassess whether you could change to a diet made with more typical ingredients,” citing the FDA investigation as the motivation for her recommendation.

(Other platformed veterinarians, such as Dr. Jessica Vogelsang and Dr. Alice Jeromin also broadcast more or less the same message: the FDA’s investigation is a reason to “get off the grain-free diet!”)

I’m writing this piece because I disagree profoundly with this interpretation of the FDA’s new investigation. I also believe that this interpretation is likely to cause harm, both to the pet food manufacturers that have been wrongly implicated (I am the founder and president of one such company) and the pets whose owners follow this “expert advice” and avoid food products that might otherwise provide evidence-based health benefits to their dogs.

The manner in which these prominent veterinarians are interpreting the FDA story is problematic for a whole host of specific reasons, all of which I discuss in greater detail below. Here’s a quick overview:

(1) Their recommendations are based on anecdotal reporting, not peer-reviewed scientific evidence. Such reasoning is completely inconsistent with what pet owners ought to expect from leading veterinary professionals, as both Dr. Weeth and Dr. Freeman themselves regularly tell their readers.

(2) The known etiology of canine DCM strongly suggests that the anecdotal reporting upon which these broad recommendations are based does not even support the recommendations in the first place.

(3) Moreover, while there isn’t any published experimental evidence suggesting a link between grain-free foods and an increased risk of canine DCM, there is peer-reviewed experimental evidence linking grain-based commercial pet foods with an increased risk of canine DCM.

(4) The evidentiary basis for the recommendations is simply dwarfed by the body of evidence supporting a related nutritional phenomenon, one with far more troubling public health implications, but which has consistently been ignored by leading veterinary nutritionists such as Drs. Weeth and Freeman—the health dangers associated with the consumption of dietary carbohydrates.

(5) The recommendation that consumers avoid all grain-free pet foods is certain to harm wrongly-implicated pet food manufacturers. But I believe it’s also likely to have, on the balance, a negative impact on the health of America’s dogs (by driving consumers towards more carbohydrate-focused products). In other words, it’s not just a poorly reasoned recommendation, it’s one that actively causes harm.

Now, I haven’t done much in-depth science writing since I published Dogs, Dog Food and Dogma in 2016. (Over the past two years, my professional life has primarily been focused on getting KetoNatural Pet Foods off and running.) But I still believe that modern-day pet owners are rarely given the informational material they need in order to make sound nutritional decisions for their pets. Given that, and given the fact that this is such a clear-cut case of flawed scientific reasoning infecting public discourse, I felt a strong compulsion to dive back into the fray, if only for a moment.

In the end, promotion of the theory that all grain-free pet foods ought to be avoided due to concerns over canine DCM is not only unsupported by the evidence, it is either an example of (at best) faulty scientific reasoning by veterinary professionals or (at worst) outright bad faith. In this piece, I’ll focus exclusively on the problems with the reasoning. But in a follow-up article, one which I expect to publish within another month or so, I’ll try to explain why some folks have gotten this one so wrong.

Now, onto the nitty-gritty. I’ll start with a few background facts and then present each of the five arguments above in greater detail.

Background

Grain-Free Diets

To properly understand the flaws in the position taken by some of America’s leading veterinary nutritionists, there are three things to note about grain-free pet foods.

The first is that they make up a mammoth chunk of the pet food market. According to PetFoodIndustry.com, 44% of dry dog foods and 47% of dry cat foods for sale in the United States today do not contain any grains. And that’s just the dry formulas! Raw, freeze-dried, dehydrated, and baked pet food products are almost always grain-free. This means that it is quite possible that most of the pet food sold in the United States today is grain-free. And, by most estimations, grain-free remains the fastest growing sector in the entire market—so if it’s not already the largest sector, it’s going to be soon.[1]

The second thing to note about grain-free diets is that, as I have already written elsewhere, there is precisely zero persuasive evidence that grains are less healthful for dogs than other sources of dietary carbohydrates, such as tubers (potatoes) or legumes (peas). In that regard, I stand in complete agreement with Drs. Weeth and Freeman—there’s no good reason to believe that grain-free pet foods stuffed with starch are particularly healthful just because the starch doesn’t come from grains.

But there’s a third and final point about grain-free pet foods that’s also critical to understand. Which is that most of the high-meat, high-protein, low-carbohydrate pet food brands on the market today (whether raw, freeze-dried, kibble, or other) also happen to be grain-free. Grain-free is such a pervasive and well-understood sector of the market, and there’s such a meaningful amount of conceptual overlap between “grain-free” and “high-meat,” that producers of truly high-meat formulas have little choice but to also make sure their products don’t contain any grains. (Again, as the president of one such company, I have experienced this pressure first-hand.) Not all grain-free pet foods contain a lot of meat, but the vast majority of high-meat pet foods are grain-free.

Canine Dilated Cardiomyopathy 

Now, to understand the significance of all this, we also have to understand a few background facts about canine dilated cardiomyopathy, the disease at the heart of the FDA’s new investigation.

First, note that canine DCM is a relatively uncommon disease, with existing evidence putting the lifetime incidence rate at perhaps 1.3-1.5% of dogs. (Only 10-11% of dogs will suffer from any form of cardiac disease whatsoever in their lifetimes. And, according to Kirk’s Veterinary Therapy XIV, a 2009 veterinary textbook, DCM accounts for about 13.6% of those.) Out of every one hundred dogs in the United States today, only one or two are likely to develop DCM in their lifetimes.

For context, consider that the AVMA estimates that about 25% of dogs will develop some form of cancer in their lifetimes. And veterinary surveys suggest that as many as half of the dogs in America today are overweight (a disease that is deadlier for a dog than a lifetime of smoking is for a human being). So one might say that cancer and obesity are, respectively, about 20 and 35 times more common than DCM. For every one case of canine DCM, there are likely 20 cases of canine cancer and 35 cases of canine obesity.

(This is not to suggest that DCM isn’t a serious (potentially fatal) disease for dogs in its own right. It is. But it isn’t remotely as common as either cancer or obesity, a fact whose significance I’ll explain below.)

Second, note that there is broad consensus in the veterinary community that a subset of canine DCM cases are caused at least in part by taurine deficiency. Taurine is an amino acid (the so-called “building blocks of protein”) found in the muscle tissue of animals, and in almost no other common pet food ingredients. Although they contain some amounts of several different amino acids, plants simply do not contain meaningful amounts of taurine.

According to AAFCO and the National Research Council, dogs don’t require any exogenous (dietary) taurine, because their bodies produce the stuff endogenously from other, more widely-available amino acid precursors (specifically, methionine and cysteine).

Cats, however, cannot conduct this transformative process nearly as efficiently as dogs can, which is why taurine is considered an “essential” amino acid for cats and why it is often said that cats are “obligate carnivores.” They need to eat meat because meat is about the only source of the taurine that their bodies require.

But, just like cats, dogs can still develop taurine deficiency. It’s just not necessarily the direct result of a lack of taurine in the diet. Studies have already documented cases of taurine deficiency-induced canine DCM that researchers attributed to either a lack of dietary cysteine or dietary methionine—the two amino acid precursors that the canine body naturally converts into taurine. And, as Dr. Freeman explained in her recent article, nutritional scientists have come up with several other theories that could explain how dogs might develop taurine deficiency:

“The reasons for taurine deficiency in dogs are not completely understood but could be reduced production of taurine due to dietary deficiency or reduced bioavailability of taurine or its building blocks, increased losses of taurine in the feces, or altered metabolism of taurine in the body.”

Evidence Linking Diet and Canine DCM 

So, to what degree has a link between dietary factors and canine DCM already been established through valid, peer-reviewed scientific evidence?

Like Dr. Freeman, I read the evidence to suggest that there is very likely a causal link between diet and canine DCM. More specifically, it seems clear to me that a diet deficient in some combination of taurine, methionine, and cysteine can cause a dog to develop taurine deficiency, which can lead to DCM.

The FDA’s new investigation seems to be an attempt to further clarify this relationship. Is it the case that some dogs require more dietary taurine, cysteine, or methionine than the relevant nutritional guidelines currently provide? Are some pet food products failing to meet those guidelines in the first place (regulatory pre-clearance is not required and studies have documented various nutritional deficiencies in the past)? Or could it be a question of bioavailability—are dogs actually able to absorb the amino acids found in certain products or ingredients?

Fundamentally, a spike in DCM cases could be attributable to any number of these factors. But what seems perfectly clear is it’s not in any way related to the presence or absence of grains in a diet. The issue almost certainly has nothing to do with whether or not a product is grain-free.

Why? It’s simple. Grains such as corn, wheat, and rice just aren’t particularly special when it comes to amino acids. Like most other plants, they don’t contain any detectable amounts of taurine. And, just like other plants, they also contain less bioavailable cysteine and methionine than the meat products and byproducts that are commonly used in pet foods.

And these differences are just examples of a broader phenomenon. The amino acid profiles of plants are very different from the amino acid profiles of meat products. Unfortunately, many pet foods (both grain-free and grain-based ones) rely heavily on plant-based protein sources to meet AAFCO’s standards concerning daily protein intake. One need not be a rocket scientist to see why: plants are typically far cheaper ingredients than meats.

But that’s as true for grains as it is for tubers, legumes, fruits, or vegetables.

What this all suggests to me is that the touchstone of any examination of the links between diet and canine DCM ought not to be focused the presence or absence of grains. (Because grains are not a meaningful better source of taurine, methionine, or cysteine than are peas, potatoes, or any other starchy commodity crop.) It ought to be focused on the diet’s amino acid content, or perhaps on the degree to which the diet’s protein comes from animal sources (since that issue is in some ways a stand-in for the amino acid issue).

Unfortunately, that is not how the veterinary community has interpreted the FDA’s announcement. To a significant degree they’ve cast a much wider net, recommending that pet owners interpret the investigation as a reason to avoid all grain-free pet foods—casting a shadow over approximately half of all pet foods in the United States today.

There are at least five reasons why that’s such a problem.

1) Veterinary Professionals Shouldn’t Make Nutritional Recommendations Based Solely on Anecdotal Evidence

The FDA’s press release is not a warning about evidence of a link between diet and canine DCM. It’s an announcement that the FDA is going to try to determine whether such a link exists.

Please read that again.

The FDA is not warning consumers to stay away from certain foods due to proven links between those foods and canine DCM. Such warnings are a part of the FDA’s usual practice—so you can rest assured that if there was a good reason to recommend that pet owners avoid some foods due to concerns over DCM, the FDA would have simply said so. But that’s not what the organization has done in this case. In this case, the FDA is simply saying that anecdotal reports have motivated it to look at the issue more closely.

In our quest to understand the truth about complex, difficult-to-understand phenomena like the relationship between diet and health, anecdotal reports simply don’t cut it. It’s just too easy for nuance, bias, and our innate cognitive limitations to cloud our judgment. Indeed, that’s the very reason why the nutritional science community exists in the first place—to separate the valid evidence from the less reliable sources of information.

And, of course, this is precisely the standard to which responsible veterinary professionals—including Drs. Weeth and Freeman—typically hold themselves. To see this in action, consider just a few recent cases of anecdotal reporting on matters concerning the relationship between canine nutrition and chronic disease:

  • Oncologists at the KetoPet Sanctuary, a non-profit treatment center in Georgetown, Texas, claim to have had tremendous success using low-carbohydrate, ketogenic diets to treat canine cancer, arguably the single worst public health problem the pet world has ever seen. And the public seems to think they’re onto something, because the organization has received significant press coverage, massive interest from pet-owners, and abundant financial investment.
  • With Facebook interest groups boasting hundreds of thousands of members, a rapidly growing market presence, and dozens of blogs and books documenting revolutionary health outcomes, a not-so-small army of pet owners believes that raw diets can solve the pet world’s most vexing chronic disease problems.

But in every one of these cases, the veterinary nutrition community has reacted in precisely the same way: by ignoring or summarily dismissing the reports. And that’s exactly what responsible vets ought to do. There’s just too great a risk that these anecdotal reports won’t stand up to scientific scrutiny. What look like causal relationships right now might well turn out to be mere coincidences when subjected to rigorous testing.

But in the case of the FDA’s recent press release, many in the veterinary community have chosen to take precisely the opposite approach—immediately amplifying and doubling-down on a theory that has zero evidentiary basis at present.

2) Even if the Anecdotal Reports Prompting the FDA’s Investigation Are Totally Accurate, They Still Don’t Support the Recommendation That Pet Owners Should Avoid All Grain-Free Foods

In its press release, the FDA clearly highlighted that taurine deficiency is a well-understood cause of canine DCM. The organization also noted that it had observed several recent cases in which dogs with DCM had low blood taurine levels. (In four other cases, dogs with DCM had normal blood taurine levels—a fact which might suggest that what’s considered “normal” in this regard needs to be updated.)

This all makes perfect sense, given what the veterinary community already knows about how DCM works. If some dogs aren’t absorbing enough of the amino acids they need to supply their bodies with sufficient amounts of taurine, those dogs might very well be eating a diet that is causing them to develop DCM. That seems entirely plausible.

But that explanation does not justify avoiding all pet foods that don’t contain grains. Nor does it justify avoiding all foods that do contain peas, potatoes, or some other non-grain source of starch. A fairer and more accurate recommendation based on the FDA’s observations might have been to avoid foods without certain amino acid concentrations or to ensure that a certain amount of animal-based protein is included in the diet.

Think of it this way: try to name one nutritional quality—let alone a quality with a plausible-sounding etiological link to DCM—that common non-grain starch sources like peas, legumes, and potatoes all share but that all grains (corn, rice, wheat, etc.) do not share. Can you do it? I can’t.

Such a quality (and I don’t believe that there is one) necessarily must exist and must be causally linked to the etiology of canine DCM in order for the recommendations set forth by Dr. Weeth and Dr. Freeman to hold water. Otherwise, even if we take the FDA’s observations as gospel, they still don’t support the recommendation to avoid all grain-free foods.

And there’s something else to consider too. We should fully expect that many (if not most) DCM cases would be eating grain-free diets, even if there is no causal link whatsoever between grain-free diets and DCM.

That’s because, as we’ve already noted, grain-free foods make up about half of the pet food market. And surely the pet owners making reports to the FDA are even more likely to feed their dogs from a market segment that (fairly or not) has developed a reputation for “premium-ness.” Of course a lot of dogs with DCM are eating grain-free diets—grain-free diets are really, really popular.

The only way to determine whether DCM rates are significantly higher in specific diet groups than in others is to conduct the kind of statistical analysis that is common in peer-reviewed studies, but absent from anecdotal reports such as the one at the heart of this case.

To my knowledge, only one researcher has published data on this issue. Dr. Darcy Adin, a veterinary cardiologist at North Carolina State University, presented a research abstract at this year’s ACVIM Forum in which she summarized the canine DCM incidence rates she had observed at North Carolina State University over a three-year period. Of the 49 cases of DCM observed at the hospital between 2015 and 2017, 22 were being fed grain-free diets and 27 were being fed traditional, grain-based pet foods.

In other words, about 44% of the DCM cases were on grain-free diets. That sounds like a big percentage and, at first glance, suggests some kind of causal link. But remember that 44% of the dog foods sold in the United States today are grain-free! And if half the dogs in America are eating grain-free diets, we should fully expect about half of all DCM cases to be eating grain-free diets too—even if there is no link between DCM and grain-free diets whatsoever.

3) At Present, the Peer-Reviewed Experimental Evidence Linking Grain-Based Diets With Taurine Deficiency or Canine DCM Actually Outweighs the Evidence Linking Grain-Free Diets to Those Conditions

For a particularly glaring example of why the recommendations voiced by some members of the veterinary community in this case amount to such a gross misinterpretation of the evidence, consider that the peer-reviewed literature already includes numerous studies in which dogs fed grain-based diets developed taurine deficiency or DCM.

In one, twelve dogs with taurine deficiency and DCM were analyzed to determine if any common characteristics could be identified among them. And, in those cases, “all twelve dogs were being fed a commercial diet containing lamb meal, rice, or both as primary ingredients.” Rice, of course, is a grain commonly used as an ingredient in traditional-style pet foods.

In another, a group of nineteen Newfoundlands included twelve taurine-deficient dogs. And, in that case, every last one of the taurine-deficient dogs was being fed a “lamb meal and rice” diet.

Is the existence of these studies a solid reason to avoid all grain-based diets due to concerns over taurine deficiency and DCM? Of course not. Because the experiments were limited in scope and because, based on what the scientific community already knows about the matter, the inadequate amino acid content of the diets is the far more likely explanation for the outcome. There’s no understood pathophysiological process that might serve as a logical explanation for a direct link between the grains and taurine deficiency, so it wouldn’t be sensible to jump to the conclusion that the grains are to blame.

And did Dr. Freeman and Dr. Weeth write lengthy blog posts highlighting these studies as evidence that consumers should avoid all traditional, grain-based kibbles? Of course not. In those cases, the studies were interpreted narrowly and grain-based diets got the benefit of the doubt, just as we’d expect them to.

The only problem is that this prudent, sensible behavior is completely inconsistent with the nature of their recommendations in the present case. Here there isn’t even publishable evidence yet, let alone a clear etiological link between grain-free diets and taurine deficiency. But sweeping generalizations have been made nonetheless.

And yet, as double standards go, this one is not nearly as eye-popping as that which results when comparing the mainstream veterinary community’s reaction to the FDA’s recent investigation with its reaction to the large and growing body of evidence supporting a somewhat related nutritional issue.

4) The Body of Evidence Suggesting Dietary Carbohydrates are Detrimental to Canine Health Simply Dwarfs the Evidentiary Record Supporting the New FDA GuidanceBut That Research Has Consistently Been Ignored by the FDA and Prominent Veterinarians

Outside of the veterinary community, a single nutritional science issue has loomed large over all others for at least the past five years: the degree to which dietary carbohydrates are playing an outsized role in fueling the epidemics of obesity, diabetes, cancer, arthritis, and many of the other chronic diseases that have vexed the public health community for decades.

A lengthy article discussing the medical community’s growing interest in ketogenic diets has been one of the most-read pieces in the JAMA network this year. Dozens (if not hundreds) of low-carbohydrate nutritional science books have been published over the past 15 years. Thousands of clinicians and research scientists have convened at conferences devoted entirely to discussing the latest in low-carbohydrate/ketogenic nutrition. (Unfortunately, the next one, at Ohio State University, is already sold out.) And, accordingly, public interest in ketogenic diets has grown explosively over the past five years.

This all makes perfect sense. Because the body of peer-reviewed research suggesting that carbohydrates are playing an outsized role in perpetuating many of the most common human health epidemics is vast and growing. Much of the evidence has been dutifully compiled by the folks at Virta Health—an organization that recently published the results of a new clinical trial in which ketogenic diets completely reversed type 2 diabetes in 60% of patients within one year—in this massive online catalog.

But inside the veterinary community it’s a different story. To my knowledge, I have written the only science book in history which endorses the theory that carbohydrates are damaging to the health of modern-day domestic dogs. With very few exceptions, there hasn’t been a peep about the matter from anyone else.

The far more common view when it comes to the links between carbohydrates and canine health is that carbohydrates are no less healthful (and perhaps even healthier) for dogs than other macronutrients. All else being equal, a carbohydrate-rich diet is so unlikely to cause adverse health outcomes in dogs that anything to the contrary doesn’t even warrant mentioning.

And not only do most mainstream veterinarians steadfastly refuse to break with this view, to date they have refused to even acknowledge alternative theories. In the human nutrition community, the healthfulness of carbohydrates is a hot button issue—academic conferences and online discussions alike are quick to descend into heated argumentation as soon as the topic of low-carb diets arises. But I have struggled for years to get even a single veterinary nutritionist to address the merits of the arguments I raised in my book. In my experience, they simply won’t touch the matter.

An attempt to distill these various arguments into narrative form would make this important piece unbearably long, so I’ll link to writing I’ve done elsewhere instead. In essence, there are at least four different reasons why I believe pet owners should consider minimizing the amount of carbohydrate in their dogs’ diets:

  1. There is unimpeachable evidence that carbohydrates induce undesirable metabolic and hormonal changes in domestic dogs. Specifically, increasing carbohydrate intake has been shown to increase insulin secretion, up-regulate glucose metabolism, and down-regulate free fatty acid oxidation. (Translation: carbs make dogs burn sugar instead of stored body fat for energy.) Evidence reviewed here.
  2. There is a coherent and compelling pathophysiological mechanism (the so-called “carbohydrate-insulin model of obesity”) and a strong and consistent body of experimental evidence suggesting that, calorie-for-calorie, carbohydrates are more fattening for dogs than other nutrients. Evidence reviewed here.
  3. There is a coherent pathophysiological mechanism (based on the fact that cancer cells preferentially burn glucose for energy) and compelling experimental evidence from other animal models (although not from dogs) suggesting that low-carbohydrate ketogenic diets may help to prevent or slow the progression of some forms of cancer. Evidence reviewed here.
  4. While the great majority of modern pet foods rely extensively on carbohydrates, there is unimpeachable evidence that the domestic dog’s genetic ancestors completely avoided dietary carbohydrates for at least 99.83% of their evolution as a canine species,[2] making the widespread consumption of carbohydrates a plausible explanation for why “diseases of modernity” (obesity, cancer, diabetes, etc.) impact modern-day domestic dogs at far higher rates than wild canines. Evidence reviewed here.

These are the potential costs of canine carbohydrate consumption. And, as you can see, the strength of the evidence supporting each individual theory varies.

On the other hand, it is a matter of consensus in the scientific community that carbohydrates are not essential nutrients for dogs. Dogs require specific amounts of amino acids, fatty acids, vitamins, and minerals in order to function optimally and avoid diseases of deficiency. But—as we should fully expect in light of how recently canine species began consuming them—they do not require carbohydrates. None whatsoever.

That is to say, our knowledge of the costs of carbohydrate consumption remains imperfect. But, critically, there are no offsetting benefits associated with chronic carbohydrate intake. All else being equal, a dog has nothing to lose by abandoning carbs—and very likely a great deal to gain.

Although you’d never know it by looking at the veterinary nutritional dogma.

For instance, consider how the country’s leading veterinary organizations—and both Dr. Weeth and Dr. Freeman individually—have told dog owners to approach the decision of whether to feed pets commercial raw-ingredient diets.

Despite their growing popularity, such products have been demonized time and time again by veterinary authorities. Their warnings typically take the form of cost-benefit analyses. The supposed costs primarily stem from the fact that raw meat can become infected with microscopic pathogens, such as Salmonella bacteria. It’s unlikely (but possible) that one will cause a dog to develop any clinical symptoms (after all, its genetic ancestors ate literally nothing but raw meat until at least the final 0.17% of their evolution as canine species.) But they can make people sick. So, the thinking goes, commercial raw diets carry a significant cost.

Technically, this is a legitimate concern supported by actual evidence. No doubt about it. It’s just not nearly as significant a concern as it has been made out to be. While it is possible for Salmonella to make dogs sick, there is only scant evidence of it actually doing so. And while the risk of transmission to humans is real, it is curtailed by common-sense safety practices, such as hand-washing and avoiding direct contact with feces. Moreover, most commercial producers employ elaborate safety measures to reduce contamination. In the end, here’s how the authors of one comprehensive meta-analysis recently described the relevant evidence:

“[T]here have been no studies conclusively documenting the risk to either pets or owners.”

In the context of the typical cost-benefit analysis, however, even a remote threat justifies the avoidance of commercial raw diets. That’s because veterinary authorities insist that these products carry absolutely no benefits.

And, again, technically, it is fair and accurate to say that raw diets are not inherently beneficial for canine health. I’ve carefully evaluated the evidence myself, and I fully agree that there is no meaningful evidence that the defining characteristic of raw diets (their “raw-ness”) is healthful in any way.

But that’s a disingenuous way to look at the issue. Because there’s another quality that sets the great majority of commercial raw diets apart from traditional kibbles, and this one is consistently ignored by veterinary authorities: they contain very few carbohydrates. While most kibble-style pet foods contain at least 40% carbohydrate (and very often much more than that!), raw diets typically contain few, if any carbs. And, as I’ve already explained, the evidence linking carbohydrate consumption with negative health outcomes in dogs is voluminous. Moreover, unlike the risks of raw meat contamination (or canine DCM, for that matter), that evidence doesn’t concern rare and uncommon issues. It relates directly to the most significant and deadly public health epidemics that the pet world has ever experienced.

In all the writing that Dr. Weeth, Dr. Freeman, the AVMA, the American Animal Hospital Association, the American College of Veterinary Nutrition, and even the FDA have done about the costs and benefits of raw diets, I’m not aware of a single instance in which any one of them has considered the significance of dietary carbohydrates. And, given the current state of the evidence linking carbohydrates and disease, that‘s a very difficult fact to explain.

Or is it?

5.) Casting Aspersions on All Grain-Free Products (Without Distinguishing Based on Protein or Amino Acid Content) Is Likely to Drive Consumers Away From Lower-Carbohydrate, Higher-Meat Pet Foods

It’s hard to ignore that the mainstream veterinary community’s perspective on the healthfulness of raw diets looks an awful lot like its reaction to the FDA’s investigation of grain-free ones. In both cases, all analyses of the underlying costs and benefits are woefully incomplete because they completely ignore the evidence suggesting carbohydrates are unhealthy for dogs. And leaving carbs out of the equation completely guts the analysis.

Unlike commercial raw diets, where the great majority of products contain few (if any) carbohydrates, it is not the case that all grain-free dry dog foods are low-carb. Extruded, kibble-style pet foods can be made using starches other than cereal grains (such as processed potatoes). Moreover, starch-stuffed plants are far cheaper ingredients than animal products and the existing regulatory regime makes it incredibly easy for producers to hide the sizable carbohydrate contents of their products. As a result of all this, many grain-free kibbles are still packed with carbs. (As of August 2017, the twelve most popular grain-free dry dog foods on Chewy.com contained an average of more than 32% carbohydrate on an as-fed basis.)

That said, it most certainly is the case that truly low-carbohydrate pet foods are almost always grain-free. And, as the founder and president of a company that produces kibble-style dog food products with less than 5% carbohydrate (on an as-fed basis), I can testify as to exactly why that is the case.

In short, fairly or not, “grain-free” means “low-carb” to millions of pet owners. And because it is so difficult under existing regulations to communicate directly with consumers on the issue of carbohydrate content, producers have little choice but to make their formulas grain-free if they want as many consumers as possible to understand that their products contain more meat and less carbohydrate than leading brands.

This is why the veterinary community’s reaction to the FDA’s investigation is not just wrong, it’s harmful too. Because demonizing all grain-free foods equally (regardless of protein or amino acid content) unfairly groups high-meat, amino acid-rich options with grain-free products that include little or no animal meat whatsoever.

And, again, I’ve experienced this first-hand. In the wake of the articles written by Dr. Weeth and Dr. Freeman, my company, KetoNatural Pet Foods, received a massive surge of e-mails from customers worried that our grain-free products would give their dogs DCM. But our products contain more than 46% protein (the great majority of which comes from animal sources), more than twice AAFCO’s recommended daily allowance of cysteine and methionine, and more than 500 milligrams of taurine per kilogram of food. There are few, if any, dry dog foods that contain more animal-based protein than ours do. Based on the existing evidence, our products are about as unlikely as any to cause a dog to develop DCM.

Nevertheless, the veterinary community’s reaction to the FDA’s investigation caused a panic amongst our customers. We were seriously damaged by the unfair generalizations.

And if the idea of for-profit corporations complaining about unfairness doesn’t exactly arouse your sympathies, consider that the problem goes a good deal further than that too. Because, in my view, the zone of damage resulting from this scandal is likely to include everyday pets as well. Because, just like with commercial raw diets, anything that serves to drive pet owners away from grain-free products is going to necessarily increase the amount of carbohydrate that modern dogs consume. And, as I explained above, there are several different solid, evidence-based reasons to believe that carbohydrates may well be playing an outsized role in perpetuating the most devastating chronic disease epidemics in the history of the domestic dog.

It is shocking that America’s leading veterinary authorities would encourage this outcome without even acknowledging the sizable body of evidence suggesting that it could be harmful to the very population they have sworn to protect. Why on Earth would they ignore such a sizable body of evidence? It’s hard to understand.

But that’s not to say we shouldn’t try to understand it.

Stay tuned. In Part Two of this series I will try to explain the unexplainable by examining the marketing tactics of a few of the pet food industry’s richest companies. I’ll be drawing on the research I conducted in connection with writing Dogs, Dog Food, and Dogma, as well as some new investigative work. There’s a pretty shocking story here, so I hope you’ll come back and check it out. I expect it to be ready for the world in about a month.

As always, thanks for reading. Keep your eyes peeled for Part Two.

[1] I disagree with both Dr. Weeth and Dr. Freeman in my perspective on why “grain-free” has so successfully become a defined market segment. It seems to me that consumers, exercising judgment that is supported by common sense, a basic grasp of evolution via natural selection, and the peer-reviewed experimental record, want pet foods that are rich in meat and low in carbohydrate content. After all, that’s precisely what the domestic dog’s genetic ancestors ate for more than 99.8% of their evolutionary heritage. Unfortunately, unlike their human-food counterparts, current U.S. pet food regulations do not require manufacturers to affirmatively disclose the carbohydrate content of their products. To a significant degree the regulations don’t even allow such disclosures. But “grain-free” feels a lot like “low-carb,” particularly when it’s paired-up with the image of a wolf. So many consumers seeking “low-carbohydrate” products wind up choosing “grain-free” ones instead.

[2] Dr. Freeman has written that wild wolves eat “berries, plants, etc.,” in addition to raw meat. This statement is contradicted by all empirical evidence. And it was described to me as “laughable” by more than one of the biologists at the Yellowstone Wolf Project with whom I lived while researching my book. It simply isn’t true.

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