Along with many in the veterinary profession, I have been following the concerns about diet-associated heart disease in dogs since 2018. A type of severe disease known as dilated cardiomyopathy (DCM) has been reported in dogs not previously thought prone to developing this malady, and it has been associated with the feeding of certain diets. These include grain-free diets, diets with exotic protein sources, and diets produced by small-scale or “boutique” manufacturers. Collectively, these foods have been referred to in some scientific papers as “BEG” diets.
Here are my previous posts on the subject-
Grain-free Diets and Heart Disease in Dogs– August, 2018
FDA Update on Grain-free Diets and Heart Disease in Dogs– January, 2019
I also recently wrote an article for Veterinary Practice News on the subject critically evaluating a narrative literature review that seemed to dismiss concerns about BEG diets and DCM. Unfortunately, this review had a number of limitations, including selective reporting of relevant findings and an undisclosed conflict of interest. Some of the authors are employees of a company which produces grain-free diets and which is actively campaigning against the idea that these diets could have negative health effects. BSM, the research group behind the review, has also accepted grant funding from a manufacturer of ingredients for grain-free diets for further research into the subject, which raises concerns about the risk of funding bias.
My most recent conclusion on the subject was this:
The scientific issue, meaning the potential causal relationship between various nutritional factors and DCM, is unresolved. Further research will be needed to confirm or refute hypotheses about any causal role of pulses, exotic protein sources, and boutique pet foods in this disease. As new research is published, however, reviewers and readers should take into account the role of financial considerations of the conclusions of various stakeholders, and the relevance of these impacts to the potential for bias in the conduct and analysis of the research.
About the same time my article was published, a virtual conference on the subject of DCM was held through Kansas State University in September, 2020.
This conference included a statement from an official of the FDA Center for Veterinary Medicine (CVM), presentations by several pet food manufacturers and representatives of industry, reports from members of the BSM research group responsible for the review article I mentioned earlier, and other research presentations. Some of the abstracts and presentations are available on the conference web site while others are not. None of the presentations refer to published, peer-reviewed research.
Not surprisingly, representatives of industry and BSM were highly critical of the hypothesis that diet might be associated with DCM in dogs, and they provided arguments and limited unpublished data to contradict this hypothesis. Other researchers provided similarly unpublished data showing that dogs with DCM who were fed BEG diets recovered from the disease with diet change and supplementation of the amino acid taurine, data which supports the hypothesized causal relationship between these diets and DCM. The FDA official was studiously neutral on the scientific question, trying to explain the role of the agency in monitoring pet food safety and keeping the public informed while not unnecessarily interfering with the interests of the pet food industry.
None of the information presented at the conference establishes a definitive answer to the role of diet in DCM, and the question requires further research to answer. However, several manufacturers have since made public statements egregiously misrepresenting the state of the science and the position of the FDA. Champion Pet Foods, for example, issued this deceptive press release:
FDA Provides Clarity About Canine Heart Disease and Diet- Evidence Finds No Causal Relationship to Grain-Free Food
BOULDER, COLORADO, November 5, 2020 – The U.S. Food and Drug Administration (FDA) issued an update this week that concluded there is no scientific evidence that a grain-free diet causes canine dilated cardiomyopathy (DCM). The agency outlined the multiple potential factors that can, alone or in combination, contribute to dogs developing this rare and scientifically complex disease. The agency concluded that there is nothing inherently unsafe about a grain-free diet. This is good news for pet lovers everywhere who, for years, have seen their dogs thrive on grain-free diets for healthy and wholesome nutrition.
This misrepresents the most recent statement from the FDA, which does not offer any such conclusion:
Historically, DCM has been primarily linked to genetic predisposition in certain breeds, but in the context of these atypical cases, emerging science appears to indicate that non-hereditary DCM is a complex medical condition that may be affected by the interplay of multiple factors such as genetics, underlying medical conditions, and diet.
FDA has not taken regulatory action against or declared any specific pet food products unsafe or definitively linked to DCM. As the scientific community looks further into the role that diet may play in these cases, we hope to explore additional avenues about ingredient levels, nutrient bioavailability, ingredient sourcing, and diet processing to determine if there are any common factors. We have asked pet food manufacturers to share diet formulation information, which could substantially benefit our understanding of the role of diet.
FDA sees this as an ongoing, collaborative, multidisciplinary scientific venture… to assess the available information and fill data gaps to determine what factors may contribute to the development of non-hereditary DCM.
Other industry organizations have issued similar statements implying that the FDA has concluded there is no causal relationship between DCM and diet, when in reality the agency has merely left the question open for further study.
Science inherently involves controversy. It functions best as a process focused on challenging and striving to prove hypotheses wrong. By its very nature, the scientific method requires criticizing the research of other scientists in order to expose bias and error in hypotheses and research methods. Unfortunately, this necessary level of controversy is unnecessarily exacerbated by the influence of ego, reputation, career goals, and money on how individual defend or attack scientific hypotheses and data. The issue of diet and DCM illustrates both the inevitable and the unnecessary conflict involved in the assessment of new ideas by the scientific community.
The core question, whether certain diets or ingredients or methods of formulation have a causal role in DCM and how, precisely, this might work remains unanswered. Those researchers hypothesizing a causal relationship and investigating this idea have always been careful to point out that the data is not yet clear nor definitive. The FDA has also been clear that they are responsible for informing the public of and investigating potential risks, but the agency has made no firm conclusion on the role of diet in DCM.
While it is understandable that critics of this hypothesis would try to undermine the arguments and evidence put forward by proponents, it is unfortunate when this is done in a disingenuous or outright misleading way. And though, undoubtedly, these critics have a genuine skepticism of the hypothesis based on the limited evidence available, the role of financial bias cannot be ignored. The publication of concerns that grain-free diets might lead to DCM, and the word-of-mouth among breed groups and pet owners with firsthand experience of this disease, have significantly affected sales of these diets. It would be naïve to imagine that manufacturers of BEG diets are unaffected in their opinions by this fact.