Grain-Free Dog Food and Heart Disease (DCM): What the Evidence Says

Grain-free dog food has not been proven to cause heart disease, and not every dog eating it develops heart problems. But since 2018, research has linked a form of dilated cardiomyopathy (DCM) to diets high in pulses such as peas, lentils, chickpeas and beans, which many grain-free foods are. The missing grains don’t seem to be the problem; the ingredients used to replace them might be, and the exact cause is still unknown.

That distinction matters, because some grain-inclusive foods are now high in pulses too. The label on the front of the bag tells you less than the ingredient list on the back.

What DCM is, and why vets noticed something odd

DCM is a disease of the heart muscle. The heart enlarges and pumps more weakly, which can lead to fluid on the lungs (congestive heart failure), irregular heartbeats and sudden death. It is a long-recognised genetic disease in breeds such as Doberman Pinschers, Great Danes, Irish Wolfhounds and Boxers.

DCM can also be secondary to something else: certain drugs, infections, toxins or nutritional problems such as a lack of taurine or vitamin B1. Two things made cardiologists suspicious in the late 2010s, according to Lisa Freeman, a veterinary nutritionist at Tufts University. They were seeing DCM in breeds that don’t usually get it, and some of those dogs’ hearts improved after their food was changed, which doesn’t happen with the genetic form.

The FDA investigation: a timeline

The US Food and Drug Administration (FDA) has led the public investigation. Its key steps:

• July 2018: The FDA announces it is looking into reports of DCM in dogs eating certain foods, many labelled grain-free.
• February 2019: A first update covers cases reported up to 30 November 2018.
• June 2019: A detailed update covers 524 reports (515 about dogs, 9 about cats) from 1 January 2014 to 30 April 2019, involving 560 dogs, 119 of which died. More than 90% of the reported products were grain-free and 93% contained peas and/or lentils; 42% contained potatoes or sweet potatoes. The FDA named 16 brands that had been reported 10 or more times.
• September 2020: The FDA joins a scientific forum at Kansas State University, where researchers discussed many different, and sometimes conflicting, theories about the cause.
• December 2022: The FDA reports 1,382 DCM reports in dogs from January 2014 to 1 November 2022. It says it still receives reports, but at lower levels than in 2018 to 2020, and that it does not plan further public updates until there is meaningful new scientific information to share.

Three points from the FDA are often lost in headlines. It has received reports linked to both grain-free and grain-containing diets. It has not asked for recalls, saying it has no definitive information that the diets are inherently unsafe and need to be removed from the market. And adverse event reports alone can’t prove that a product caused a disease. The FDA’s investigation covers the US, but many of the same foods and ingredients are sold worldwide.

What the research has found since

Tufts’ June 2026 update says more than 30 scientific studies have now been published on diet-associated DCM. These are the main findings so far.

It’s about pulses, not grains. Diet-associated DCM appears to be linked to diets high in pulses, including both grain-free and grain-inclusive foods. Soy, also a legume, hasn’t been implicated. Tufts notes that peas show up most often, but that may simply be because peas are the most common pulse in dog food: in 2017, 51% of dry dog foods contained peas, 23% chickpeas and 14% lentils.

It isn’t mainly a nutrient shortage. Early suspicion fell on taurine. A 2018 study by Kaplan and colleagues found 24 Golden Retrievers with DCM and low taurine, 23 of them on grain-free, legume-rich diets or both; 23 improved after a diet change and taurine supplements. But later studies found normal taurine in most affected dogs of other breeds. In a 2022 prospective study of 60 dogs with DCM, none had low taurine.

A possible mechanism has emerged. In 2025, Tufts researchers reported that dogs with DCM eating high-pulse diets had higher levels of a urine marker linked to phospholipidosis, an abnormal build-up of a type of fat inside cells. The marker correlated with how pulse-heavy the diet was. It’s a lead, not an answer, and the team says it is now investigating this and other causes.

Hearts can recover, partly. In a 2021 study of 71 dogs with DCM, those eating non-traditional diets whose food was changed lived a median of 337 days, against 215 days for those whose food wasn’t changed. In the 2022 prospective study, dogs that had been on non-traditional diets showed small but significant improvements in heart function after a diet change.

Changes may start before symptoms. A 2023 study of 46 healthy dogs found those eating non-traditional diets had lower ejection fraction (a measure of how well the heart pumps) and larger left ventricles than dogs on traditional diets.

The other side of the debate

Not everyone agrees with the diet link, and it’s fair to say so. A 2020 review by McCauley and colleagues described the early publications as opinion-based, said many variables had not been separated, and argued that FDA reports were open to sampling bias unless vets reported every DCM case, whatever the dog ate. A 2022 study by Quest and colleagues surveyed 14 US referral hospitals and found no significant change in the share of DCM diagnoses between 2000 and 2019, and no correlation with grain-free food sales. That study was funded by BSM Partners, which employed four of its five authors, and some authors overlap with the 2020 review.

Tufts researchers, for their part, argue the FDA’s numbers are likely “the tip of the iceberg”, because diagnosis needs an echocardiogram and reporting is voluntary and time-consuming. Both camps agree on one thing: the specific cause hasn’t been proven.

Our read: the association with high-pulse diets is consistent across several independent teams, the mechanism isn’t settled, and nobody knows yet what share of dogs on these foods are affected. That’s a reason to be thoughtful, not frightened.

What vets currently advise

The FDA’s advice is short: talk to your vet before changing your dog’s diet. Your vet may bring in a board-certified veterinary nutritionist.

Tufts’ guidance is more specific. In its 2023 update, it suggests that a diet with pulses (peas, pea protein, lentils, chickpeas and so on) in the top ten ingredients, or multiple pulses anywhere on the list, “might put some dogs at risk”. For dogs diagnosed with DCM or early heart changes, its team recommends a reduced-sodium diet without pulses or potatoes, together with the right medical treatment.

Practical steps if you feed a grain-free or pulse-rich diet:

1. Read the full ingredient list. Note where peas, lentils, chickpeas, beans and potatoes appear, including “pea protein” and “pea fibre”.
2. Ask your vet at the next check-up. Mention the food and how long your dog has eaten it. Bring the bag or a photo of the label.
3. Watch for heart signs. Coughing, faster breathing at rest, tiring easily, fainting or a swollen belly.
4. Consider a heart check if there are any signs. A murmur or irregular heartbeat can be a reason for an echocardiogram, which is the test that diagnoses DCM.
5. Plan any change of food with your vet, especially if your dog has other health conditions.

Our guide on how to choose a dog food covers what to look for on a label more generally.

See a vet now if:

• Your dog is breathing fast or hard while resting or asleep
• Your dog has fainted or collapsed, even briefly
• Your dog has a new cough, especially at night or after lying down
• Your dog’s belly is swelling or their gums look pale or grey
• Your dog suddenly can’t manage normal walks

Which dogs are affected?

Any breed can develop diet-associated DCM, including breeds that are also prone to the genetic form. In the FDA’s 2019 data, the most reported breeds were Golden Retrievers (95 dogs), mixed breeds (62) and Labrador Retrievers (47), followed by Great Danes, Pit Bulls and German Shepherds. The FDA cautioned that Golden Retrievers were probably over-reported because of breed-specific social media activity.

Tufts says most affected dogs had eaten non-traditional diets for more than a year, sometimes many years, and that not every dog eating them develops heart problems. Cats seem to be susceptible too, though less so.

If your dog is diagnosed, Tufts urges owners to report the case to the FDA to help the investigation. Outside the US, ask your vet about your national pet food or veterinary medicines regulator.

The bottom line

The worry about grain-free food is really a worry about diets heavy in peas, lentils and other pulses, and the evidence for a link to DCM has grown since 2018 even though the cause hasn’t been pinned down. Not every dog eating these foods develops heart problems, so there’s no need to throw out the bag tonight. Read the ingredient list, raise it with your vet, and act quickly on signs such as coughing, fast breathing at rest or fainting. If your dog does have heart changes, a diet change plus proper treatment gives the best chance of improvement.