Since the FDA report investigating the links between grain-free food and DCM was released in July 2018, we've been paying a huge amount of attention to the topic. We completely appreciate your concern as a pet parent - as a company (and as pet parents ourselves) we pride ourselves on, first and foremost, cooking healthy, safe food for the dogs we feed. Our in-house team of Registered Veterinary Nurses have taken the time to write a blog post about the reports outlining our formal response to any claims. You can find this here.
A timeline of investigations, including research that has complied more than 150 studies has concluded that there is no conclusive link between grain-free diets and dogs suffering from DCM. Many of the articles can be accessed through the Journal of Animal Sciences website.
What is Dilated Cardiomyopathy (DCM)?
DCM is a disease of the heart muscle where the heart chambers become enlarged (dilated) and one or more valves may leak. The cause of DCM is unclear in most cases, certain breeds may be predisposed. Large dog breeds like Doberman, Irish Wolfhound, Great Dane, Newfoundland, and Golden Retriever are most often affected. Having said that, it also affects smaller breeds such as the American Cocker Spaniels. A DCM-like heart muscle dysfunction can develop off the back of an infection - but this is generally rare. Some nutritional deficiencies can affect the heart’s normal function too. These nutrients specifically include the proteins Cysteine, Methionine and Taurine.
A bit about these proteins
Dogs have essential and non-essential amino acid (protein) requirements. Taurine is a non-essential nutrient for dogs, meaning their bodies synthesise it from essential amino acids in food - cysteine and methionine. When diets contain sufficient amounts of ingredients containing these nutrients, their bodies do the rest. Taurine, cysteine and methionine are naturally highest in meat muscle, heart, liver and Brewer’s yeast - all of which are found in Butternut Box recipes.
In our recipes, the main ingredient is 60% high-quality fresh meat (50% in our game recipe). We regularly test our meals for Taurine, Cysteine, and Methionine levels at an independent lab and although there aren’t currently any minimum levels of taurine required, Cysteine and Methionine levels in our food are well above the minimums outlined by NRC, AAFCO and FEDIAF guidelines. Just for reference, FEDIAF protein/amino acid requirements are significantly higher than those required by AAFCO and NRC, so we feel really confident and secure with our results.
Legumes
Legumes are a broad category of food that includes pulses (peas, beans, lentils and chickpeas). Our meals contain a combination of approximately 10-15% cooked lentils, peas or green beans. These ingredients are a rich source of protein, B vitamins, phytonutrients and fibre. And there is currently no scientific evidence in any species, including humans, linking DCM to legumes.
Cooking process
We mention our cooking process because it’s different to others on the market. Our meals are gently cooked at 90°C which means our proteins are a bit more protected than those in foods cooked at higher temperatures. This is also a key point to make because any brands mentioned in the FDA report were all dry food manufacturers - and all cooked at higher temperatures than 90°C.
Our team of academics and professionals in the space
We take the responsibility of feeding four-legged family members very seriously. Our co-founders Kev and Dave started Butternut because they wanted to help fix the problems they found as pet parents buying dog food that was available on the market. But they never pretended to have a PhD in nutrition. That’s why every ingredient, recipe and process has been signed off by some of the most experienced academics and experts in nutrition - who all do have a PhD.
Our team is driven by peer-reviewed science and evidence, not speculation or association. And when they analysed the FDA report and ongoing investigations into DCM and the possible association with grain-free dog foods, their conclusion is that Butternut Box's high-quality ingredients; Taurine, Cysteine and Methionine content lab results; and gentle cooking process, all mean that there is currently no scientific reason to believe there is any link between our meals and DCM.
A timeline of DCM investigations
July 2018 - The FDA issued a brief statement that they were investigating recently reported cases of a type of heart disease known as dilated cardiomyopathy, or more simply, DCM. The brief noted that some dogs who had this disease may have been fed certain types of diets.
June 2019 - Continued to investigate and gather information to identify if there is a specific dietary link to the development of DCM. No UK or European link or investigation has been made or is underway at the minute. It’s worth noting at this point that the latest FDA report is not a peer-reviewed scientific study, but a collection of data from a relatively small number of dogs in the U.S.
June 2020 - Research that has compiled more than 150 studies found there is no conclusive link between grain-free diets and dogs suffering from DCM.
August 2021 - Examined the relationship between certain compounds in peas and any relationship affecting the reduced function in the amino acid Carnitine, which is important for dog heart muscle contractility. They suggest fibre levels may influence nutrient digestibility, rendering nutrients less available. The researchers concluded they could not establish with certainty that any of the ingredients or compounds studied are cause for heart disease.
March 2022 - The incidence of DCM was statistically analysed in relation to the significant increase in sales of grain-free diets from 2011-2019. The study shared DCM patient details from 2000-2019, a total of almost 70,000 dogs. The conclusion - as grain-free diets increase in popularity and sales, the incidence of DCM did not.
December 2022 - The conclusion is that, after multiple FDA reports, countless articles and opinions, billions of dollars spent in response and research, or lost in sales, and sky-high levels of confusion and anxiety among everyone- vets, dog owners, retailers, pet food brands- no link has been made between diet types and non-hereditary DCM and the FDA does not intend to release further public updates. Regarding ingredients, FDA states it has insufficient data to establish causality among DCM case reports and pet food products or certain ingredients eaten
May 2023 - A clinical study carried out by the University of Guelph examined dietary inclusion of 0% to 45% lentils, peas, chickpeas and pinto bean ingredients. Throughout the study, the dogs, no matter which diet fed, showed no changes in echocardiographic measurements from baseline. Nor did their cardiac biomarkers demonstrate any indications of cardiac stress or DCM development. It is welcoming to see scientists examining ingredients in further detail and finding no cause for concern.
May 2023 - A 28-day feeding trial comparing grain based and pulse based diets found that while a diet heavily based on wrinkled peas (not garden peas) led to sub-clinical changes in cardiac function and elevated NT-ProBNP (a biomarker for heart stress), a lentil-based diet did not cause these DCM-like changes. Notably, plasma taurine levels remained unchanged across all diets, suggesting that lentils do not negatively impact taurine bioavailability or prompt early DCM markers in the way other specific legumes might (Quilliam et al., 2023).
October 2023 - A clinical study carried out by the colleges of veterinary medicine at the University of Missouri and Washington State University examined 65 dogs eating high and low protein diets, and grain-inclusive and grain-free diets over a 7-month period. This study did not detect the development of DCM or any cardiac dysfunction throughout its duration through the echocardiographic parameters measured, cardiac biomarkers, or endomyocardial biopsies.
July 2024 - A 180-day feeding study examined dogs on four commercial diets with varying protein levels and carbohydrate profiles (both grain-inclusive and grain-free). The researchers tracked key heart-health amino acids, taurine and carnitine in the dogs' blood, skeletal muscle, and heart muscle.
All four diets successfully increased blood taurine levels and maintained them within healthy target ranges, regardless of whether the food contained grains. Additionally, the study noted that standard blood tests don't strongly reflect amino acid levels in heart tissue itself, suggesting blood tests alone may not tell the whole story of a dog's heart health.
July 2025 - A randomised, 18-month prospective study published in the Journal of Animal Science evaluated healthy adult dogs fed four different diets with varying carbohydrate sources, including grain-free (with peas and potatoes) and grain-inclusive options.
The researchers found that taurine levels remained completely normal and unaffected by diet, with no negative impacts on heart function across any of the groups. These results reinforce that complete and balanced recipes support overall heart health, regardless of whether they are grain-free or grain-inclusive.
Butternut Box and DCM
At Butternut Box, we take our commitment to providing high-quality, complete and balanced nutrition for every dog we feed seriously.
We are working continuously with the Scientific Advisory Board of FEDIAF (a committee of veterinary and animal science nutrition experts) to review research data.
We are talking directly to the Chairman of the SAB on this matter to stay close to their ongoing discussion.
We are actively working internally and with other industry peers (especially in the US) to continue our own research and learn more about DCM. We use certified independent laboratories for all of our quality control analysis.
We continuously conduct analyses of the nutritional composition of our meals, including proteins and amino acids. These are regularly repeated.
We have conducted studies on the digestibility of protein within our meals. Compared to other super-premium dry dog foods, Butternut Box meals are extremely digestible. This allows ideal protein (taurine, cysteine and methionine) bioavailability and absorption.
A Glossary of Abbreviations
FDA - Food and Drug Agency (US based only). They investigate and advise on food and drug policies.
FEDIAF - this one is the official European Pet Food Industry. They interpret research, legislation and publish nutritional guidelines.
AAFCO - Association of American Feed Control Officials. The American equivalent to FEDIAF. They have their own set of pet nutritional guidelines.
NRC - The National Research Council is the working arm of the United States National Academies, which produces reports that shape amongst others, nutritional guidelines.
Reference
Bradley W. Quest, Stacey B. Leach, Shiva Garimella, August Konie, Stephanie D. Clark, Incidence of Canine Dilated Cardiomyopathy Diagnosed at Referral Institutes and Grain-Free Pet Food Store Sales: A Retrospective Survey, Frontiers, 17th of March 2022, Sec. Animal Nutrition, Volume 3 - 2022 https://doi.org/10.3389/fanim.2022.846227
Morris, E. M., Stiers, C. A., Hancock, L. B., & Gross, K. L. (2025). Different carbohydrate sources in dog foods supported overall health and cardiac function: an 18-mo prospective study in healthy adult dogs. Journal of Animal Science, Vol. 103, skaf225.
https://doi.org/10.1093/jas/skaf225McCauley, S. R., Clark, S. D., Leach, S. B., Quest, B. W., & Streeter, R. M. (2024). Evaluation of taurine and carnitine concentrations in whole blood, plasma, skeletal muscle and cardiac muscle in dogs. Journal of Animal Physiology and Animal Nutrition, 108(4), 999–1015. https://doi.org/10.1111/jpn.13946
Quilliam, C., Reis, L. G., Ren, Y., Ai, Y., & Weber, L. P. (2023). Effects of a 28-day feeding trial of grain-containing versus pulse-based diets on cardiac function, taurine levels and digestibility in domestic dogs. PLOS ONE, 18(5), e0285381. https://doi.org/10.1371/journal.pone.0285381