Diet, genetics play roles in canine DCM; Mysteries remain

Among more than 150 published studies related to DCM, researchers didn’t find any firm connection among cases of DCM and grain-free dog food.

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(O_Lypa | BigStock.com)
(O_Lypa | BigStock.com)

The ultimate causes of canine dilated cardiomyopathy (DCM) may be diverse, complex and specific to each case, as opposed to a simple cause and effect with certain grain-free dog foods. Among more than 150 published studies related to DCM, a pet industry consulting group's researchers didn’t find any firm connection among cases of DCM and grain-free dog food. However, in their analysis of existing studies published in in the Journal of Animal Science, the scientists did note recurring dietary and genetic factors that need more attention.

“We don’t necessarily have a great grasp on how this multifactorial disease process develops in all dogs,” Dr. Renee Streeter, DVM, study co-author and principal clinical nutritionist with BSM Partners, a pet industry consulting agency, said. “However, at this point we know that genetic factors and certain dietary factors can affect a dog’s likelihood of developing DCM. There are also infectious causes that may result in a DCM phenotype. Dietary factors known to play a role in the development of DCM in dogs are; certain unsupplemented low-protein diets and unsupplemented lamb-based diets. Certain breeds are also more prone to taurine deficiency related to DCM including Cocker Spaniels, Newfoundlands and Golden Retrievers. It is possible that other ingredients may be associated with an increased likelihood of developing DCM, especially in predisposed breeds, but further research is needed to make that determination.”

Streeter’s review didn’t crack the case of DCM. To the contrary, it revealed how many holes remain to be filled by further research.

“This review article summarizes the current data available and was necessary in order to point out the lack of controlled studies and misinformation right now,” Streeter said. “We can’t fully understand the relationship between diet and DCM based on the current information.  We have encouraged, and continue to urge, researchers to perform proper controlled studies that will offer clear insight into the variables that contribute to the development of DCM.  This will help ensure industry is creating appropriate diets for dogs that help them live their best lives.”

FDA investigation into DCM and grain-free dog food

In July 2018, the U.S. Food and Drug Administration’s (FDA) publicly announced the agency’s investigation into correlations among certain dog foods and DCM. Federal authorities examined reports of DCM in dogs eating certain diets labeled as grain-free, particularly those containing peas, lentils, other legume seeds, or potatoes as main ingredients, which were more common in diets labeled as grain-free. A year later, the agency released data from their investigation that stated 93% of the 524 reported cases of DCM, involved dog foods made with peas and/or lentils, while 90% of the afflicted dogs had eaten diets labeled as grain-free. The FDA named 16 brands most frequently eaten by dogs involved in official reports of DCM. Sales of grain-free dog food in general, and those named brands especially, fell following FDA’s announcements, while more new products began to include taurine. Pet food companies adapted their marketing, while developing new dog foods, treats and toppers specifically meant to ease pet owners fears of DCM. Instead of claiming that all grain in pet foods were negative, brands became “grain friendly” as they began to include ancient grains or other “healthy grains, while continuing to malign conventional grains like wheat and corn.

Although the FDA investigation caused upheaval in the pet food industry, scientists and other involved with the pet food industry have pointed out the lack of direct evidence connecting those grain-free dog foods to DCM, since the first FDA announcement. Likewise, some have criticized the FDA for going public with the investigation before solid evidence existed, especially considering the negative economic consequences for dog food brands.

Canine dilated cardiomyopathy heart disease

DCM affects dogs’ heart muscles. The disease results in an enlarged heart. As the heart and its chambers become dilated, pumping becomes more difficult and heart valves may leak, leading to a buildup of fluids in the chest and abdomen. DCM often results in congestive heart failure. Heart function may improve in cases that are not linked to genetics with appropriate veterinary treatment and dietary modification, if caught early. Breeds that are typically more frequently affected by DCM include large and giant breed dogs, such as Great Danes, Boxers, Newfoundlands, Irish Wolfhounds, Saint Bernards and Doberman Pinschers. It is less common in small and medium breed dogs, except American and English Cocker Spaniels. Cases reported to the FDA included Golden and Labrador Retrievers, Whippets, a Shih Tzu, a Bulldog and Miniature Schnauzers, as well as mixed breeds.

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