Is Grain-Free Dog Food Causing Heart Disease?

In recent years, veterinarians have been noticing an upsurge in cases of enlarged heart in dogs. Also called dilated cardiomyopathy (DCM), it’s a serious and often fatal heart condition.

The FDA’s Investigation of Grain-Free Dog Food and Heart Disease

Many of the cases of DCM have involved dogs that were fed grain-free diets, suggesting that diet may play a role in this disease. This alarming trend led the US Food and Drug Administration (FDA) to launch an investigation into whether diet and other factors are putting pets at risk of developing DCM.

The FDA has since released a series of reports summarizing the investigation’s findings. You may be wondering what these findings mean for your pets, and which foods are safe to feed them.

Are grain-free diets bad for dogs? What is causing the recent outbreak of DCM cases? Although the FDA’s investigation is still ongoing, here’s what you need to know and what you can take away from the latest news on this serious disease.

Dilated Cardiomyopathy

What Is Dilated Cardiomyopathy? 

DCM is a heart condition that is characterized by an enlarged heart size and thinning of the heart muscle. These changes weaken the heart’s ability to pump blood, so the disease tends to be progressive and eventually leads to heart failure.

Dilated cardiomyopathy can affect both cats and dogs. Canine DCM has traditionally occurred in middle-aged and older dogs, especially large and giant-breed dogs, such as the DobermanGreat Dane and Irish Wolfhound. Because specific breeds are susceptible, this had suggested that the disease has a genetic cause. But in cats, DCM is caused by a deficiency in taurine, an amino acid that can’t be synthesized by the body and must be obtained in the diet. Once researchers found that low taurine was the cause of feline DCM, manufacturers began adding taurine to commercial cat foods to ensure that cats received adequate amounts. As a result, feline DCM is now very rare. That raises the question of whether diet plays into a dog’s chance of developing DCM.

Is Diet to Blame for DCM in Dogs?

 Within the past several years, DCM has been occurring more frequently in dogs than before. And instead of just targeting large breeds, these newer cases are affecting a wide variety of breeds, including dogs that hadn’t been considered to be at high risk for DCM. This suggests that a factor other than genetics is causing disease in these pets.  

In response, the FDA teamed up with diagnostic laboratories, veterinary cardiologists, and nutritionists to investigate the recent DCM cases in dogs. They requested that veterinarians report any cases of canine or feline DCM to the FDA.

A total of 560 dogs with DCM have been reported so far, and the FDA is using these cases to look for any trends that may have factored into the disease. In particular, they’re focusing on blood tests, diagnostic findings (such as symptoms and echocardiogram measurements) and diet, as well as other factors.

Not Just Grain Free

Does the Research Point to Grain-Free Diets?

 Unlike the genetic form of DCM, the recent DCM cases have affected a wide range of dog ages and breeds, from puppies to older dogs. The most commonly reported breeds with DCM have included the Golden RetrieverLabrador Retriever and mixed breeds.

When the FDA reviewed dietary factors, they found that over 90 percent of dogs with DCM were being fed diets listed either as “grain-free” or “zero grain.”

Instead of grains, these diets contained peas and/or lentils as their main ingredients. A lower proportion of the diets also listed potatoes or sweet potatoes as a top ingredient.

The researchers examined many other components in the diets, such as protein source, minerals, carbohydrates and starches, but none of these other components trended with disease development.

It is also worth noting that according to the FDA, the diets of dogs in reported cases had “high concentrations/ratios of certain ingredients such as peas, chickpeas, lentils, and/or various types of potatoes,” which is typical of grain-free diets, but diets that contained grains were also represented among these cases.

The Role of Taurine in Canine DCM

 The investigators also looked into low taurine as a possible cause for the recent cases. So far, these results have been inconclusive. Just under half of the tested dogs in the report were taurine-deficient, while the remaining half had normal taurine levels.

Other studies, however, suggest that taurine may play a bigger role in DCM, especially for certain dog breeds. One study found that 24 Golden Retrievers with DCM had low taurine, and most of the dogs were fed grain-free diets prior to diagnosis.

Fortunately, the heart disease resolved for nearly all of the dogs after they received cardiac medications and taurine supplements and switched to a grain-inclusive diet.

Are Other Factors Involved?

 So far, the FDA report’s biggest finding is that nearly all dogs with DCM were fed grain-free diets. This suggests a strong link between grain-free foods and heart disease in these pets.

The FDA hasn’t yet determined the exact mechanism for how the disease forms. To cover all bases, the FDA and partnering agencies are continuing to research any possible factors, such as genetics, heavy metal exposure and other toxicities, that are possibly contributing to DCM development.

Is It Safe to Feed a Grain-Free Diet?

 The FDA’s study of DCM in dogs is still underway, and on their Q&A page, they state:

“At this time, we are not advising dietary changes based solely on the information we have gathered so far.” 

But if you have concerns about feeding diets with certain ingredients, your veterinarian can help determine the most appropriate foods for your pet’s individual needs.

Although grain-free pet diets have become popular in recent years, it’s important to keep in mind that grain sensitivities and allergies are actually very rare in pets, compared to humans. So most pets don’t require a grain-free diet.

Regardless of which diet you’re feeding, if your pet shows any signs of heart problems, such as a cough, breathing difficulties, weakness or collapse, you should contact your veterinarian as soon as possible.   

By: Natalie Stilwell, DVM, MS, PhD

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