Grain-Free Dog Food and DCM: What the Research Actually Says Now

For years, pet owners were warned that grain-free dog food could cause dilated cardiomyopathy, or DCM. That message became so widespread that many people still believe “grain-free causes heart disease” is settled science. It isn’t.

The evidence available today has not shown that grain-free diets, as a category, cause DCM. In fact, newer research has failed to find the increase in heart disease we would expect to see if grain-free foods themselves were creating a widespread problem.

How Did the Concern Start?

Around 2017 and 2018, veterinary cardiologists began reporting DCM in some dogs that were not breeds traditionally considered highly predisposed to the disease. Some of those dogs were eating grain-free foods, which was a legitimate reason to investigate, but an observation is not the same thing as proving causation.

Veterinary nutritionist Dr. Lisa Freeman of Tufts University helped popularize concerns about what she called “boutique,” exotic-ingredient and grain-free diets, later referred to as “BEG diets.” At that point, however, there was no definitive research showing that boutique or grain-free diets caused DCM.

The FDA opened an investigation in 2018 and repeatedly described the issue as a potential association rather than a proven cause. The agency has since stated that it does not know the specific connection between the reported diets and non-hereditary DCM, and reports have involved dogs eating both grain-free and grain-containing foods.

FDA Reports Are Not the Same as Disease Incidence

After the FDA warning received national attention, reports of DCM increased. But reports submitted to the FDA are not the same thing as proving that the disease itself became more common. The FDA has acknowledged that adverse-event reports can help identify a possible signal, but those reports alone cannot establish that a product caused a disease.

So one of the bigger questions is what happened to actual DCM diagnoses as grain-free foods became more popular.

A 2022 study looked at more than 68,000 dogs seen by veterinary cardiologists from 2000 through 2019, a period during which grain-free pet food sales increased dramatically. Researchers did not find a significant national increase in the percentage of dogs diagnosed with DCM, nor did they find a significant correlation between DCM incidence and grain-free food sales.

That doesn’t mean diet can never contribute to DCM in an individual dog. It does mean the evidence doesn’t support reducing this complicated issue to “grain-free food causes DCM.”

What About Taurine and Genetics?

DCM existed long before grain-free foods became popular. Genetics are a well-established factor, and certain breeds have known predispositions to the disease. Nutrition can play a role as well.

Taurine deficiency has long been associated with some forms of nutritionally responsive DCM, and certain dogs may be more susceptible to taurine or amino-acid problems than others. Some dogs with DCM have improved after taurine supplementation and diet changes. At the same time, taurine deficiency does not explain every case, and not every dog included in the FDA reports had low taurine levels.

The bigger takeaway is that DCM can involve genetics, metabolism, amino-acid status, diet and other individual factors. It isn’t simply a matter of whether there are grains in the food.

What Does the New 2026 Research Show?

The newest major study comes from the Dog Aging Project and looked at whether dogs eating grain-free diets were more likely to develop new cardiac diagnoses. Researchers analyzed the data using several statistical models and found no statistically significant association between grain-free feeding and new cardiac diagnoses.

In other words, in this large population of dogs, eating a grain-free diet did not predict a higher risk of developing heart disease. That doesn’t close the book on every possible diet-related heart issue, but it adds to the evidence that the words “grain-free” alone don’t tell us very much about a food’s potential effect on heart health.

What About Industry Relationships?

Some researchers involved in the DCM discussion have disclosed relationships with major pet food companies. Dr. Lisa Freeman, for example, has disclosed professional and research relationships with several large pet food manufacturers, including Nestlé Purina PetCare.

Those relationships are relevant disclosures and should be transparent, but they don’t automatically invalidate someone’s research. We think the more useful question is the same one we ask whenever we evaluate pet nutrition claims: What does the actual evidence show?

The Bottom Line

Grain-free diets have not been proven, as a category, to cause DCM. The FDA investigated a legitimate concern, but the much broader message many consumers ultimately heard — “grain-free causes heart disease” — went beyond what the evidence actually established.

We now have evidence showing that DCM is strongly influenced by genetics in many dogs and that taurine deficiency and other nutritional factors can contribute in some cases. We also know that DCM diagnoses did not significantly increase as grain-free food sales grew dramatically, and the new Dog Aging Project research found no significant association between grain-free diets and new cardiac diagnoses.

At Odyssey Pets, this is why we believe in looking at the whole food instead of chasing labels. Grain-free doesn’t automatically mean better, and grain-inclusive doesn’t automatically mean healthier. Dogs and cats have no established dietary requirement for carbohydrates, so our goal is to help you feed as much quality animal-based nutrition as possible, with the highest meat content and lowest carbohydrate levels that make sense for your pet, your budget and your lifestyle.

Whether that means fresh, frozen, freeze-dried, canned or a high-quality kibble, the goal is simple: help you feed your pet better — not scare you into or out of a food because of one word on the bag.

Sources & Further Reading

For anyone who wants to dig deeper into the research, we encourage you to read the science for yourself.

2026 Dog Aging Project Study — Veterinary Medicine and Science
https://onlinelibrary.wiley.com/doi/10.1002/vms3.71213

FDA — Questions & Answers: FDA’s Work on Potential Causes of Non-Hereditary DCM in Dogs
https://www.fda.gov/animal-veterinary/animal-health-literacy/questions-answers-fdas-work-potential-causes-non-hereditary-dcm-dogs

Tufts Petfoodology — The Role of Carbohydrate in Pet Foods
https://sites.tufts.edu/petfoodology/2021/07/07/the-role-of-carbohydrate-in-pet-foods/

AAFCO — Understanding Pet Food & Reading Labels
https://www.aafco.org/consumers/understanding-pet-food/reading-labels/