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Grain-free diets and a disease on the rise: Dilated Cardiomyopathy (Enlarged Heart)

In DCM, or dilated cardiomyopathy, the heart muscle is weakened and can cause abnormal heart rhythms, the heart becomes enlarged, congestive heart failure or sudden death can occur. DCM was on a downward turn since the early 2000’s, however it has begun to rise again. It is a mystery that veterinarian cardiologists and the FDA are currently working on. DCM is associated with certain breeds, typically large and giant breeds, but in recent years this has also included non-typical breeds like Golden retrievers and small breeds like French bull dogs.

Early on, DCM used to be one of the most common heart diseases in cats. In 1987 when the lack of taurine was discovered as the primary cause, it was added as a supplement to all commercial diets for cats. Yea!

Luckily for dogs, they can make their own taurine. Unfortunately, as the public is more aware of pet health through proper nutrition, DCM is again on the rise in our dogs; possibly due to the trend of feeding grain-free!

The likely suspect causing DCM, was a taurine deficiency, however not all dogs diagnosed were taurine deficient. For some dogs having DCM, it was found to be caused by dietary insufficiencies, others with an unknown cause, and a third group had DCM completely unrelated to diet. What seems to be consistent is that dogs having DCM were more likely eating grain-free, exotic ingredient or boutique (smaller manufacturers selling food targeted at a niche market) diets.

Grain-free and exotic ingredient diets in and of themselves are not necessarily bad, but expecting nutritious results just by an ingredient list without delving into the science of how ingredients work together, may be the cause of this new development. These diets require nutritional expertise and extensive testing and a company committed to rigorous quality control.

DCM could be a diet related issue; regarding bioavailability due to ingredients interacting with other ingredients, or an ingredient even having an unknown toxic component affecting the heart. As an example, the bioavailability and metabolism of taurine is different in a lamb-based diet compared to a chicken-based diet OR bioavailability can be affected by the amount and types of fiber in the diet.

The rise of these diets and the rise of DCM in pets being fed them is concerning. Worse we understand this comes from the deep love people have for their pets and only wanting the very best for them.

Marketing is a powerful tool, and the pet food industry is an aggressive marketer telling you all sorts of things to make you think their food is the best and why the Other guy’s food is not good for your pet. We feel at this point marketing has outpaced science.

To paraphrase our Dr. Andrew Maglott, due to a preponderance of evidence at this time, we strongly suggest not feeding grain-free foods especially to puppies of any breed, and higher-risk large and giant breeds.

We will update as more information becomes available on this topic. If you have been feeding one of these diets and your dog develops symptoms of DCM: shortness of breath, intolerance to exercise, coughing or fainting please call and make an appointment to have your dog examined.

Sources: by Lisa M Freeman DVM, PhD, DACVN by Lisa M Freeman DVM, PhD, DACVN

Additional information: Updated July 8th, 2019 source: FDA

“Between January 1, 2014 and April 30, 2019, the FDA received 524 case reports of diagnosed dilated cardiomyopathy. Some of these cases involved more than one animal from the same household. In the reported cases, there were 560 individual dogs diagnosed with DCM and 119 of those dogs died. There were 14 individual cats, 5 of which died. The agency received additional reports of cardiac symptoms in dogs, however, the reports did not include a confirmed DCM diagnosis.

There is a range of different brands and formulas included in the reports and some reports named multiple brands and/or formulas. The FDA has compiled a spreadsheet of all DCM case reports submitted through April 30, 2019. Brands named most frequently in reports submitted to the FDA (as of April 30, 2019) that had at least ten reports, include:

Acana (67), Zignature (64), Taste of the Wild (53), 4Health (32), Earthborn Holistic (32), Blue Buffalo (31), Nature’s Domain (29), Fromm (24), Merrick (16), California Natural (15), Natural Balance (15), Orijen (12), Nature’s Variety (11), NutriSource (10), Nutro (10), and Rachael Ray Nutrish (10).”

The FDA is urging pet owners to work with their veterinarians, to obtain the most appropriate dietary advice. We believe that while a small number of patients may require grain-free diets for management of chronic illness, most dogs and cats are being fed these diets as the result of heavy marketing and the misconception that grains cause illness.

Additional information: updated January 2021

A new literature review in June of 2020, published in the Journal of Animal Science, calls into question some of the facts about the link between BEG (boutique, exotic, grain-free) diets and DCM. Researchers pointed to several data-collection and analytical problems in some of the previous studies and concluded that: The use of the acronym BEG and its association with DCM is unmerited as “no definitive link has been established at this time.”

In summary, in order to determine if certain ingredients, categories of diets, or manufacturing processes are related to an increased risk of DCM, further studies investigating these variables such as the “benefits and negative effects of dietary fiber” when formulating diets should be considered. Future studies are "needed to evaluate one variable at a time and to minimize confounding variables and speculation." (There is speculation, however that it is multiple factors in BEG that cause DCM to occur.) Furthermore, "the veterinary community should be asked to provide information for all cases of DCM in dogs.”

We agree about needing further studies, however we should point out that many of the scientists involved with this study are affiliated with BSM Partners – a consulting group for the pet industry. This doesn’t necessarily imply bias but is important to note.

The initial FDA report found: Based on the data collected and analyzed thus far, the agency believes that the potential association between diet and DCM in dogs is a complex scientific issue that may involve multiple factors.

There has been a significant increase in the number of dogs diagnosed with DCM who were not pre-disposed. Most cases were reported after the FDA report was made in 2018. Vets were probably not looking for a food connection prior to that time with DCM. While there are certainly plenty of unreported DCM cases caused by diet, considering that there are around 77 million pet dogs in the US, it is still a fraction of the pet dog population. Will DCM cases affiliated with BEG continue to rise, now that veterinarians are aware of a possible correlation and looking to rule that out during diagnosis?

It must be considered if feeding grain-free is worth the potential risk. At around $3.50 a pound on average, probably not, if there is no medical reason to feed grain-free.

Our bottom line: there is enough evidence to be concerned about the BEG role in DCM. We do not recommend feeding BEG diets unless there is an underlying medical condition that requires it.

sources: FDA report, K9 of Mine article written by Meg Marrs and reviewed by Dr. Jode Klerk DVM, article in Journal of Animal Science June 2020 Vol 98 #6

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