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It's been four long years since the 2018 announcement from the FDA about a heart disease called DCM and it's potential link to certain types of grain-free or pulse-legume heavy diets, and the conversation is still dominated by disinformation.
Three and a half updates from the FDA and eight epidemiological studies later, there's a lot we still don't know. There's a decent bit we do know, too. We know enough to make risk-minimizing decisions based on the information available, while research continues into the foreseeable future, and these risk-mitigation decisions have the potential to save lives. We know that dogs are still being diagnosed and passing away from this disease. Unfortunately, the narrative available to pet owners through social media and trending articles isn't one that reflects the research and the reality in veterinary clinics.
When the FDA made their announcement, it sent waves through the dog-owning community. These waves were amplified greatly with the infamous 2019 update that brought a list of most-named brands submitted in cases reported. The pet food industry, particularly manufacturers and private retailers of 'boutique' type diets, scrambled to minimize the damages. Pulse legume interest groups sought reprieve. Since that time, there has been a steady and discouraging stream of misleading, if not outright inaccurate assessments of the issue peddled to pet owners, presumably in an effort to save falling profits. For those without a financial stake in the matter, it's less clear what underlies such disingenuous dialogues.
Our dogs deserve better. And pet owners deserve better. Our dogs deserve safety; assurance that the commercial diets on the shelves are adequate and nutritious and free of hazards. Pet owners deserve truth and integrity-- straightforward facts fully contextualized to make informed decisions. Instead, we have articles providing only fragments of the story, omitting details and building a picture that only barely approximates reality. These articles tend to take off on social media, being shared hundreds to thousands of times, often alongside commentary dismissing and de-legitimizing concerns that veterinarians still express.
Take an example, published 04/06/2022 on The Science Dog blog: "The (Dis)connection between Grain-Free Foods and DCM," shared over 100 times on Facebook already. This article briefly summarizes the findings of a number of feeding trials studies and relates that to the current DCM issue. Unfortunately, the article fails to adequately elaborate on why those studies aren't particularly useful for approaching these cases clinically, described in more detail below. Even more unfortunately, the article then goes on to discuss the recent survey study from BSM Partners that seems to conclude DCM has not been diagnosed more frequently alongside the rise of grain-free pet food sales-- without nearly sufficient data to even begin answering that question.
The article characterizes the study as having looked at "over 68,000 confirmed cases of DCM. Over the 10-year period of 2011 to 2019, DCM incidence among dogs did not increase significantly." While this description sounds promising, it fails to elaborate on those 68,000 cases and 10-years in full context. Only 14 clinics responded to the survey (16% of the 88 contacted). Of those, only seven provided more than 4 years of data. Only three provided any breed data. And those 14 clinics did not include the several major referral centers that have been actively recruiting for research studies on DCM, likely drawing referrals (and therefore cases) from other specialty clinics. A full critique of the study is available. In short, though, the data collected is just not enough to answer the question posed.
Also missing from the discussion is the impossible-to-ignore, and not openly disclosed, financial conflict of interest that BSM Partners holds. Conflict of interest alone does not indicate that there are methodology flaws or suggest that research is insufficient. However, when coupled with data interpretation and discussion that exceeds the ability of the data to draw meaningful conclusions, or press releases that mischaracterize the scope of a study's findings, it raises prominent ethical concerns that are worth paying attention to. SkeptVet has written about this particular group's conflict of interest previously.
BSM Partners is a pet food formulation firm, and at least one of their clients is Zignature, a brand among the top named in the FDA's 2019 update to the public. Even more concerning, BSM Partners has received explicit research funding to the tune of over $175,000 from a number of pulse interest groups, including Columbia Grain International (self-professed as one of the largest pulse exporters in North America), the Northern Pulse Growers Association, and the USA Dry Pea and Lentil Counsel. The intentions of these groups are questionable. Consider the following:
- "“The FDA has just put a knife into the back of the pulse industry,” pet food maker Sarah Barrett said at a farm industry gathering last month in Redwood Falls, Minn. ... “Every time they release these statements every six months, social media goes nuts,” Barrett said. “And then we lose market share.” "
- "Absent any conclusion about what’s causing the canine heart problems, lawmakers from major pulse-growing states are starting to put their own pressure on the FDA." - 2019 Politico article
- Interestingly enough, the FDA did go silent towards the public shortly following pressures, as discussed previously on this site, questioned during the FDA's Pet Food Listening Session, and reported on by The Canine Review.
- "The North American pulse industry has lost an estimated 250,000 metric tons of sales to pet
food formulators since the first FDA announcement in 2018."
- “The APA and the USADPLC have joined with several others in the pet food industry in a coalition to fight these baseless claims that have devastated our markets. We are optimistic that science will be on our side.”
- "“Pet food is one of our fastest-growing markets for the pulse industry,” says grower Gordon Stoner of Stoner Farms in Outlook, Montana. “I support this research to protect this vital market.” The American Pulse Association and the USA Dry Pea and Lentil Council board of directors have pledged a total of $100,000, Pulse Canada pledged an- other $100,000 and the Northern Pulse Growers Association has pledged $125,000 to kick-off our DCM Research Fund Campaign." - May 2020, Pulse Pipeline
- "The DCM research fund campaign is aimed at uncovering the causes of DCM in dogs and challenging the assumption that pulse crops including lentils and field peas, are causing DCM." - 2020 article from The Western Producer
While it's lamentable that a major market has been negatively impacted by this disease and investigation, protecting market interests cannot come at the expense of pet health and wellness. The research indicating these products are safe should have come before their use rose, not after and in the face of disease.
The FDA's investigation began for several reasons, all of them intended to protect pet health. Atypical breeds were developing DCM, a disease usually restricted to those breeds predisposed and the rare 'idiopathic' instance. Many of these dogs were eating diets disproportionately represented among cases. Top estimates suggest grain-free diet is at most 40% of the market. 91% of cases involved grain-free diets. In 2017, peas were found in 5% of dry dog foods. This number likely climbed since '17, but not to the 89% of cases reported eating diets with peas. Some of the most frequently reported manufacturers have a market share of less than 1%. The exact cause for why these trends are observed could take years, if not over a decade, to fully understand. In the meantime, risk mitigation measures can be taken, and for many that means avoiding these diets until we know why the association exists. That is likely not an easy pill to swallow for the industry when sales drop.
The result? Pet owners seem to be being taken advantage of in the name of profits. Consider these excerpts from an article in The Western Producer published last year, titled "Pampered pets provide profitable market for pulses":
"As Fido and friends have moved from the doghouse to the people house, pet nutrition has been elevated to big business and big opportunity for pulse producers. ... It’s a phenomenon called “pet humanization,” a trend that accelerated with the COVID-19 pandemic. With this new level of affection comes owners’ willingness to shell out more money for their “fur babies.” How much more? According to the American Pet Products Association, sales of pet food and treats in the U.S. increased nearly 10 per cent in 2020 to more than $53 billion. Young said pet food represents a growing market tier for pulses such as peas, chickpeas and lentils. Product that didn’t meet the grade for human consumption used to end up steeply discounted and sold as livestock feed. Pet food provides a higher-paying alternative. In the case of chickpeas, he said this has large calibre product going into the premium export market. Medium calibre goes to canneries. Byproduct such as sorter colour rejects, splits, chipped and smaller calibre can go to the pet food market. ... Pet food’s created a huge opportunity … to sell No. 2 or better product into. I buy a lot of No. 2 product, but what pet food’s done is created a huge market that wasn’t really there before.”"
After reading above, ask yourself if the health of your pet is the priority of this industry. Why is it that the feeding trials involving the impact of these ingredients on canine metabolism are happening in the last several years? Why did it take hundreds of dogs reported ill, and a Federal investigation, and a decline in profitability to finally decide that these ingredients are worth researching? Should that research not have been a priority before the inclusion of these ingredients rose? That question alone should speak volumes.
As far as the feeding trials go, most of them simply have not been designed to provide useful, clinical insight into this present issue of DCM and how it may relate to these diets. It's always good to have more nutritional insight to the ingredients used in pet food, but the data collected does not address either determining the association to diet or isolating a cause or mechanism if the association is non-spurious (as it appears to be, given that cases are diet-responsive for recovery). The studies discussed in The Science Dog's article span from 7 days long at the shortest to three months at the longest. Only one monitored cardiac parameters. Most of the studies focused on taurine or other amino acid metabolism. Here is why these studies don't do much to inform this issue:
- Taurine is not currently the suspected culprit. Affected dogs have tested at a range of taurine values, low, normal, and high. There is concern that some dogs may be testing high as an indicator of myocardial (heart muscle) damage, releasing taurine into the circulation.
- Seven days is not a sufficient period to assess the long-term outcomes associated with feeding a particular type of diet. That some of these studies showed changes to metabolism as early as one week is concerning when wondering what the consequences of that are after months or years of use.
- Without including cardiac parameters, which only one study did, no amount of nutrient analysis will indicate whether or not the use of the diet is, for some reason or another, associated with cardiac changes.
In a call to 'follow the science,' it's unfortunate that not all of the science was represented. There have been numerous studies since 2018 analyzing data from DCM cases alongside diet history and identifying concerning trends. An additional study that would have fit very well into the article in question was a foodomics study published last year that attempted to identify compounds unique to diets associated with DCM. Despite limitations, this study had some success, opening the door for further, targeted inquiry. It’s especially unclear why that study in particular, which can be used to guide further food trial research, wasn’t discussed in the article. Here is what studies have found:
- The 'foodomics' study (Smith et al 2021) identified several compounds unique to, more common in, or found in higher amounts within associated diets. This has suggested several potential mechanisms that can now be investigated further, such as:
- Unnamed compounds that could potentially be cardiotoxic
- Decreased vitamin B levels, which could impair amino acid metabolism
- High levels of a compound previously documented to inhibit carnitine transport into heart tissues
- Multiple studies (Adin et al 2019, Freid et al 2020, Walker et al 2021, Freeman et al 2022) have found that a diet change is associated with improved outcomes for dogs that have DCM and are eating non-traditional diets, including complete disease resolution.
- Length of time on a grain-free diet has been associated with worse outcomes in dogs with DCM (Walker et al 2021)
- Among healthy dogs, grain-free high-pea high-lentil diets have been associated with elevations in Cardiac Troponin I, a biomarker of heart damage (Adin et al 2021)
It is said that history repeats, and sadly there is a poignant example available that parallels what is happening with the atypical/non-hereditary/diet-associated DCM investigation. The entire tale, and experience, is described firsthand in a Ted Talk by veterinarian, pathologist, and researcher, Dr. Ilze Matīse‑VanHoutan. Her involvement was with an outbreak of canine mega-esophagus in Latvia. For the academically inclined, the outbreak is described in a 2021 JAVMA paper. Mega-esophagus is a disease that prevents normal movement of the muscular tube between the mouth and stomach. It can have a number of causes, but in this instance, cases were occurring at a much higher rate than usual among dogs eating a certain diet. Researchers began to look for a cause, and the pet food company denied culpability. Ultimately, funding was cut off and had to be crowd-sourced. Veterinarians warning the public were sued by the company. Pet owners sharing their stories on social media were targeted with lawsuits. And in the end... public awareness led to action, sales dropped four-fold for the company, and so did case rates of the disease. A definitive cause was never identified.
Megaesophagus is easier to identify and diagnose than DCM (it causes chronic regurgitation of food and water, readily observed and a trigger for concern in pet owners. DCM can have no signs or subtle, non-specific signs like decreased activity. Mega-e can be diagnosed with x-rays at virtually any veterinary office. DCM is diagnosed by echocardiogram with a specialist). Latvia is also a smaller country than the USA, making the outbreak there and case number more amenable to monitoring than with DCM here. Nonetheless, the pushback and denial rings close to home for the veterinarians and pet owners facing a similar battle with regards to DCM. Despite the struggle she faced, Dr. Ilze Matīse‑VanHoutan's closing words are of hope:
"So, now our year looks like this, and you can see there is a significant decrease in the case numbers. (Applause) We're approaching our historic levels. We achieved our goal: we helped the dogs, and we found the truth. But this story is not just about dogs. It is a story about our society, taking action into our own hands, away from politics, back to science and ethics. And that makes me very proud. If we could do it, others can do it too. It's also the story about keeping our integrity, even when facing resistance. And this is especially important for us, scientists and professionals. This is how we can make our lives better and live with a clear conscience. We could not have done this without a huge support from professionals, the public at large, and independent media. So I want to say many, many thanks to all people who have supported us in works, words, and thoughts."
Veterinarians hold a responsibility to their patients and their clients to do no harm and to make well-informed recommendations. These recommendations are based on the level of evidence available, which often includes, for better or worse, clinical experience and case reports before high level evidence is available. For the vast majority of patients, there is no benefit associated with grain-free or pulse-legume rich diets. For those that do need a grain-free diet, there are a small number of well-researched and pulse-low or pulse-free options available on the market. There are also safe, very well-researched diets available on the market with formulas numbering in the hundreds to address the wide variety of needs for individual companion animals and their owners.
It's fine to acknowledge that there is a lot we still don't know about these DCM cases.. but research is going to take time. In that time, veterinarians owe it to their patients to be proactive and take relatively benign risk mitigation measures based on the limited information available: when eating certain grain-free, pulse-legume-rich diets, atypical breeds have developed DCM and resolved signs when switched off that diet. Given the unknown mechanism, it's true that risk mitigation measures advising avoidance of certain diets cast a wide net, and likely do include avoiding diets that aren't truly problematic or associated with disease. That reality, or recognition of it, does not mean that we should sit idly and apathetically by, tossing our hands up and pretending that the problem doesn't exist or cannot be addressed until we know why it exists. Consider grapes: without knowing why or when some dogs seem to experience kidney injury after eating some amount, the easy solution is to not feed grapes and treat all instances as potentially toxic ingestion.
The question we need to ask this this: are we all in on preserving the industry at the potential expense of pet health, or on preserving pet health at the potential expense of the industry?
The cost of caution may be reduced profits for certain sectors, but surely we can all agree that the lives and health of our dogs are worth that price. The market can adapt.
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