BENTONVILLE, ARK. — In a recent benchmark study published June 17, a group of veterinarians, veterinary cardiologists, and animal nutritionists from pet care research and consulting firm BSM Partners has determined the available studies looking at the potential causes of dilated cardiomyopathy (DCM) in dogs do not support a link between diet and the disease.

The team of researchers published the peer-reviewed article in the Journal of Animal Science. The study is an exhaustive literature review of the causes, confounding factors and nutrient implications of DCM, and the first research resulting from BSM Partners’ long-term DCM research effort.

“We wanted to gain the best understanding of this issue, so we examined the results of more than 150 studies, which taken together did not support a link between grain-free and legume-rich diets, and DCM,” said Dr. Sydney McCauley, an animal nutritionist and the article’s lead author. “What the science does make clear is that DCM is largely an inherited disease.”

In a supplementary press release issued June 25, Renee Streeter, DVM, DACVN, Board Certified Nutritionist and co-author of the literature review, added, "To be clear, our review article in the Journal of Animal Science is not original research, this article is an examination and summary of existing published research. While we found no definitive relationship between grain-free, legume-rich diets and DCM, we firmly believe that more original research is needed,

"It is important that we fully understand the true causes of DCM, and we call upon our peers to perform and publish further peer-reviewed controlled studies on this topic," Streeter said.

In addition to finding no definitive relationship between certain grain-free or novel protein diets and DCM, the article details the incomplete information in the US Food and Drug Administration’s (FDA) reported cases of DCM and why these gaps in available information make it impossible to draw any definitive conclusions from this data. Future studies are needed to evaluate one variable at a time and to minimize confounding variables and speculation.

“We believe that further research is needed in order to reach sound conclusions with respect to the relationship between diet and DCM,” said Dr. Eva Oxford, a veterinary cardiologist and an article coauthor. “This is why BSM Partners has initiated multiple original research projects that will shed additional light on this topic.”

BSM researchers noted that while the FDA has referenced many reported cases of DCM in dogs eating grain-free or legume-rich diets, the majority of these cases contained incomplete information. For example, integral data such as the dog’s complete diet history, age or the presence of concurrent conditions were often missing.

Additionally, some of the reported cases were of dog breeds with a known genetic predisposition to DCM, which further confounds the claim of a dietary role. Genetic inheritance is the most commonly known cause of DCM in dogs, according to the BSM study.

Several other confounding variables were determined to have skewed data about what causes DCM in dogs leading up to this point, including insufficient samples sizes, nutrient bioavailability and synthesis discrepancies across canine breeds and sizes, and supplementary treating and feeding habits that could affect nutrition or nutrient absorption.

The article also details published research highlighting a number of other factors that could contribute to the presence of DCM. These include nutrient deficiencies, myocarditis, chronic tachycardia, and hypothyroid disease.

BSM researchers point out the inconsistent use of diagnostic tools and the potential variance of those measurements could also yield inconclusive conclusions in determining the causes or implications of DCM.

The study draws attention to the FDA’s public announcement about the potential link between certain pet food formulations and the development of DCM, which was first published July 12, 2018. Because of this public notification, researchers believe increased media attention and awareness in the public and veterinary communities could have led to a perceived increase of reported DCM cases. This could also lead to breed reporting biases and overrepresentation, BSM researchers explained.

However, it is noted that published incidents of DCM suggest between 308,000 and 1 million dogs living in the United States could have the disease at any given time, which represents 0.4% to 1.3% of the total canine population. The FDA report included 560 cases of DCM in dogs potentially linked to dietary limitations, which represents just 0.05% to 0.1% of dogs with DCM in the United States.

While the study recognized certain nutrient deficiencies — including taurine, carnitine, thiamine, copper, potassium, vitamin E and selenium — have been associated with the development of DCM in dogs, further research is needed on how these nutrients are absorbed by dogs of different breeds, ages and sizes, as well as nutrient relationships with regard to bioavailability.

In sum, the 20-page article highlights the need for more objective data to be collected and analyzed, without sampling bias and confounding factors.  

The article, which was received by the Journal of Animal Sciences January 30 and accepted May 4, can be accessed through the Journal of Animal Sciences website.

BSM Partners is a full-service pet care research, consulting, and strategy-to-shelf product innovation firm. BSM Partners’ research professionals collaborate with clients to formulate, validate and process roughly 800 new products each year.

Read more about canine DCM and implications on ingredient categories.

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