The Four Essentials of Canine Dilated Cardiomyopathy (DCM) in 2024

This article is an accompaniment to a podcast episode we recorded a few weeks ago and which you can find here. It's also an outgrowth of the DCM lawsuit we filed against Hill's Pet Nutrition and a cluster of affiliated individuals and organizations in February of this year, as well as other research work we have done to shed light on fraud and other forms of misconduct committed in connection with the DCM scandal.

The purpose of the article is to highlight and explain what we think are the four most important things dog-owners should know and remember about nutritionally-mediated canine dilated cardiomyopathy as of the spring of 2024. As with any topic that is still being investigated by the scientific community, knowledge about the subject changes as time passes and new evidence comes to light. And we'll be sure to keep you updated with the latest developments. But as of today, when it comes to DCM there are four specific things that are particularly important to remember in order to make good health and nutrition decisions on behalf of your dog.

Before we begin the overview, let's cover the necessary background material. (This is a very high-level review. For a more in-depth treatment, here's some further reading.)

DCM is a very serious (often deadly) disease of a dog's heart muscles, which results in the heart becoming large and "leaky."  Heart diseases are less common among dogs than among people, but as canine cardiac diseases go, DCM is relatively prevalent. More particularly, by 2010 (before the rise of grain-free diets) it was already generally considered the second most common cardiac condition among dogs.

As such, the disease was already quite well-studied prior to 2018. In fact, there was already a consensus in the veterinary community that DCM had both genetic and dietary causes, with certain breeds predisposed to it and certain nutritional qualities likely to increase its risk or severity.

But in July of 2018, this somewhat obscure canine heart disease became front page news (literally), when the United States Food and Drug Administration announced that it was beginning a public investigation into whether "grain-free" dog foods -- a huge and diverse group of products -- were causing dogs to develop DCM. According to the FDA, the agency launched its investigation after receiving a "spike" in reports of DCM in dogs being fed grain-free foods.

The FDA's investigation raised DCM's profile dramatically. And, over the past six years, as the FDA has carried out its investigation, the disease has remained more or less the most talked-about pet food topic in the country, particularly among veterinary professionals. Most major media outlets stopped covering the subject at some point along the way, but a few groups of researchers regularly put out new papers about the "potential association" between grain-free diets and DCM, keeping it top-of-mind among veterinary communities even as updates about the FDA's investigation tailed off as the investigation proceeded.

And, with the reminder that the foregoing is only a very high-level summary, that just about brings us to the present day. So where does it leave things? What should dog-owners understand and remember about the state of DCM today? Primarily, four things.

1. The FDA's Investigation is Over And Found No Evidence That Grain-Free Dog Foods (Or Any Other Group of Products) Cause DCM

In December of 2022, the FDA announced that it was essentially ending its investigation, stating that it had found no evidence suggesting that grain-free or "BEG" ("boutique, exotic, or grain-free") diets cause or exacerbate DCM. Over the more than four years that passed during the pendency of the FDA's investigation, millions of dollars were spent carrying out a host of different studies testing the "potential association" between grain-free diets and DCM. And hundreds of individual DCM case reports were submitted to the FDA by pet owners around the country. The FDA scrutinized all that material and came to the firm conclusion that, in the end, none of it suggested there was any kind of link between grain-free diets and DCM whatsoever.

Here's how journalist Tim Wall, writing in Pet Food Industry magazine, described the relevant science:

"Despite the FDA investigation’s effect on the pet food market, scientists didn’t find evidence connecting certain diets to cases of DCM. More than 150 published studies didn’t reveal to researchers any firm connection among cases of canine dilated cardiomyopathy (DCM) and grain-free dog food."

Since in science you can never really "prove a negative," the FDA's DCM investigation will never really be completely over. The agency will always encourage dog-owners to send it reports of cases of canine DCM that are suspected to have been caused by diet and it will remain open to evaluating new peer-reviewed evidence that may warrant further examination in the future. And if the FDA's understanding of the science of DCM changes, we will all hear about it. But, for now, the FDA's DCM investigation is essentially over because the agency determined that ---after more than four years of looking---it has found no evidence that grain-free or "BEG" dog foods actually play any role in causing DCM.

2. There is Also No Evidence That Grain-Free Dog Foods Are Correlated With Higher Incidence Rates of DCM or Worse DCM Outcomes

This is likely the single most important fact to know and remember about the present state of DCM research.This is because so many people (including, embarrassingly, so many veterinary professionals) are simply getting it wrong.

Even proponents of the theory that DCM is caused by grain-free dogs foods must admit that the FDA has ended its investigation and found no evidence that the diets cause the disease. That much is just impossible to deny. It's just a Google search away at all times.

Instead, folks who continue to push the idea that DCM "appears to be associated with" grain-free diets often characterize the FDA's findings as very limited. They claim that the FDA is only saying that it has yet to find conclusive evidence that grain-free pet foods definitively cause DCM. Which, they argue, isn't all that significant. What's important is something the FDA has left unsaid: that while definitive proof of causation is very difficult to develop, there is already plenty of evidence that grain-free diets are correlated with DCM. 

There's just one problem: the idea that there is evidence that DCM is correlated with higher rates of DCM or worse DCM outcomes simply isn't true. Anyone who says otherwise is either deliberately misrepresenting the truth or has been innocently misled by one of the faux-scientific tricks we'll outline below.

The truth about the present state of the peer-reviewed DCM research is quite straightforward: there is no evidence to suggest that dogs fed BEG diets have higher incidence rates of DCM or experience worse disease symptoms/progression compared to dogs on so-called "traditional" diets. Period. No one has ever published a paper showing that dogs on grain-free diets get DCM more commonly than dogs on "traditional" diets. And no one has ever published a paper showing that dogs with DCM die sooner, die more often, or otherwise get "worse" while on grain-free diets than on traditional diets.

What lots of people have done is publish papers that "involve," in one way or another, both DCM and grain-free diets. In the years since the FDA launched its investigation, more than a dozen different scientific papers have been published that have at least something to do with both DCM and grain-free diets. (The vast majority of them were written by defendants to our lawsuit.) And proponents of a link between DCM and grain-free dog foods often describe this body of research as showing "an association" between the diets and the disease.

But that description is categorically false. In reality, none of the papers show any statistical association whatsoever between grain-free diets and DCM incidence rates, DCM mortality rates, DCM symptoms, or any other clinical signal of disease progression.

So why are so many smart people with formal training in scientific literacy failing to notice this misrepresentation? In essence, they're being tricked. As explained in greater detail in paragraphs 180-194 of our lawsuit, there are four different ways that the authors of these DCM papers have used sleight-of-hand to make the papers appear to support their claims that the disease is "associated" with grain-free diets, when in reality they don't.

Explaining all four of these tactics is beyond the scope of this article. But if you want to understand them, just follow the link above and spend a few minutes digesting the relevant material. (You won't need an advanced degree, the material consumes several pages but isn't particularly technical or confusing.)

3. There Is Evidence That the DCM Investigation Was Induced By Fraud Perpetrated By A Leading "Traditional" Pet Food Company and A Group of Affiliated Researchers and Organizations

As noted above, in early February of this year a class action lawsuit alleging fraud in connection with the DCM scandal was filed on behalf of KetoNatural and all other similarly-situated grain-free pet food brands. This is a vital fact for pet-owners to understand about DCM because it helps to explain why so many veterinarians hold the false belief that grain-free pet foods have been shown to cause (or be "associated with") the disease, when in reality they haven't.

You can read a summary of the key allegations from the suit here. In essence, a small group of veterinary researchers deliberately misled the FDA into launching its DCM investigation by sending the agency cherry-picked data about the diets of dogs they had recently diagnosed with DCM. More specifically, they cherry-picked cases of DCM involving grain-free diets and submitted those to the FDA while simultaneously withholding cases involving so-called "traditional" diets. This gave the FDA the false impression that grain-free diets were more common among dogs with DCM than they really were. Which is what sparked the investigation.

As evidence submitted to the court in connection with the suit shows, these veterinarians all had significant financial ties to a "traditional" pet food brand called Hill's Pet Nutrition, the self-proclaimed "#1 choice of veterinarians" in the United States and a company that, as explained below, has benefited enormously from the FDA's investigation.

Once the FDA launched its investigation, these same veterinarians began a campaign of spreading misinformation about the science of DCM, publishing all manner of academic papers, blog articles, quotes in major media outlets, veterinary education seminars, and social media posts falsely asserting that there was scientific evidence that DCM is "associated with" grain-free diets, when in reality no such evidence exists.

This scheme accomplished two particularly notable things. First, it caused countless veterinary professionals to develop the false belief that there is evidence that grain-free diets increase the risk or severity of DCM in dogs, when in reality there is no such evidence. Second, it produced a massive financial windfall for Hill's as consumers abandoned grain-free brands due to concerns over DCM. To understand the scale of this windfall, take a look at this chart (which comes from the lawsuit):

As you can see, Hill's revenues were pancake flat in the years leading up to the FDA's investigation. But once the investigation began the company's revenues began to grow explosively. In the five years preceding the investigation, Hill's grew a total of about 1%. In the five years since the investigation began, the size of the company has nearly doubled. A more abrupt financial turnaround is difficult to imagine.

The lawsuit will play out over the months and years ahead. And we'll do our best to keep you informed about the latest developments. But for now it's important to pet-owners to understand that there are credible, evidence-backed allegations that the entire DCM scandal is the result of fraud carried out by the very company that benefited most from it.

4. There Is Evidence That Inadequate Intake of the Essential Amino Acids Cysteine and Methionine Can Cause or Exacerbate DCM in Dogs

The fourth and final thing all pet-owners need to understand about diet-associated canine DCM in 2024 is that there most definitely are nutritional causes of DCM in dogs, they just don't have anything to do with whether or not a diet contains grains or comes from a "traditional" pet food brand.

Long before there was an FDA investigation into DCM there was already a body of scientific literature regarding nutritional causes of DCM whose main findings almost everyone in the veterinary nutrition community agreed upon. 

More specifically, scientists had already worked out that there are two specific kinds of amino acids (substances that are the so-called "building blocks of protein") that dogs need to consume in sufficient quantities in order to avoid an elevated risk of DCM. These two amino acids are called cysteine and methionine.

In dogs, these two amino acids are the raw materials used to synthesize taurine within the body. And taurine plays a vital role in preserving healthy cardiac function and avoiding DCM. But dogs can't synthesize cysteine and methionine endogenously, so they need to ingest them as parts of their diets.

This is the primary reason why the Association of American Feed Control Officials requires all "complete and balanced" dog foods to contain specific amounts of cysteine and methionine. Because if dogs don't consume enough of these amino acids their bodies can't make taurine. And if they can't make taurine, they are more likely to develop DCM and other cardiac problems.

There is absolutely no reason to believe that "traditional" pet foods contain more cysteine or methionine than grain-free ones. Not only is there no evidence of this in the scientific record, but since many grain-free diets contain much more crude protein and meat-based protein than many "traditional" diets (and since cysteine and methionine are found in abundant quantities in meat-based protein), it's not even a plausible hypothesis. Our Ketona Chicken Recipe, for instance, contains about twice as much crude protein as Hill's Science Diet Chicken and Barley Recipe. Hill's doesn't disclose the cysteine and methionine contents of their products, but ours contains about 300% of AAFCO's minimum requirements for the two nutrients.

More generally, dog-owners can prioritize cysteine and methionine intake by choosing diets rich in meat-based proteins, as those ingredients are naturally abundant in both amino acids. By ensuring adequate intake of these essential nutrients, pet owners can help mitigate the factors that have actually been shown to increase the risk of DCM in their dogs.

So, to recap, when making nutritional decisions for dogs, we think there are four specific things all pet-owners should remember about DCM:

1) The FDA ended its DCM investigation after finding no evidence that grain-free pet foods cause DCM.

2) Despite what many veterinary professionals have been led to believe, there is no scientific evidence that grain-free diets are correlated with higher incidence rates of DCM or worse DCM outcomes.

3) There is a major new lawsuit (supported by credible evidence and 125 pages of specific allegations) that the entire DCM scandal was deliberately induced by fraudulent activity perpetrated by Hill's Pet Nutrition and a cluster of affiliates.

4) The best nutritional strategy for minimizing your dog's DCM risk is feeding a diet rich in the meat-based amino acids cysteine and methionine.

That's all for now. Thanks for reading. We'll do our best to keep you updated with the latest DCM news in the months and years ahead.