Grain-Free Dog Food and Heart Problems: What We Know

There are no definitive answers yet on the possible connection between certain grain-free diets and dilated cardiomyopathy (DCM) in dogs.

Grain-free dog food heart problems
Does grain-free dog food cause heart problems? Photo: 

A summer 2018 report from the U.S. Food and Drug Administration (FDA) alerting consumers to a possible connection between certain types of grain-free dog foods to a heart condition known as dilated cardiomyopathy (DCM) has put some people in a panic.

With the safety of these dog foods called into question, you may be wondering if the diet you’re feeding your pet is as healthy and safe as you thought it was.

Keep reading, and we’ll try to explain everything.


First, Why Grain-Free Food?

Grain-free dog foods have risen in popularity, paralleling the increased interest in gluten-free and grain-free diet trends for humans.

Take a walk down the aisles of any pet store and carefully study the pet food labels. What you see on the shelves are stacks of products labeled as “grain-free” or “gluten-free.”

Here’s Why People Think Grain-Free Is Best …

Why have grain-free dog foods become some popular? The argument in favor of them goes something like this:

  • Dogs are descended from wolves. The natural diet of their ancestors consisted of prey animals such as rabbits, deer and small rodents.
  • When a wild dog made a kill, very little of their prey went to waste. The dog would eat not just the “steak” (or muscle) but also the skin, hair, organs, bones, intestines and whatever was inside the guts.
  • Which means grains didn’t form a big part of their ancestral diet. Therefore (the argument goes) a dog’s digestion is not geared up to digest large amounts of grain or gluten. So adding lots of grain to dog food makes it harder to digest.
  • Since grains are cheaper than good-quality meat protein, they become labeled as a “cheap filler.” This makes grains in pet food sound like a really bad idea.

… And Here’s Why That’s Nonsense

Leaving the physiological argument about digestion to one side for a moment, comparisons with a wild dog lifestyle are silly. Just ask yourself: What’s the life expectancy of a wild dog?

Whereas a wild dog has a short life expectancy of around just 2 years1, our pampered pooches live on into their teens. To hold wild dogs up as an example of what’s desirable is to overlook a lot of suffering. It ignores the wild pups who didn’t survive into adulthood because of worms, salmonella or clostridial infections.

Then there’s the misery of parasites and poor health in adult dogs and those unfortunates who died horrible deaths from bowel impaction due to a bone blocking the gut.

Question: Why would we want to emulate wild canids that don’t live as long as our pets? Go figure.


No, Your Dog Probably Doesn’t Have Grain Allergies

But this truth aside, many people say their dogs have grain or gluten allergies as proof that dogs aren’t meant to eat a lot of plant-based material. But even this is misrepresented.

Right now the only known reason for dogs to avoid grains is when a grain allergy is present — which is actually very rare. A dog is more likely to have a food allergy to a meat protein (such as beef, lamb, chicken or rabbit) than gluten.

Dogs with grain allergies present with vague symptoms, such as itchiness and rashes, which improve when they stop eating formulas containing grains. However, dogs can be itchy for any number of reasons (including the odd flea bite), and a home diagnosis of gluten allergy is a big assumption to make.

Dogs are more likely to have a specific meat allergy than a grain/gluten allergy. Photo: Designs by Jack/

OK, What Is Gluten?

Before building gluten up or knocking it down, what exactly is gluten?

Gluten is a plant protein.2 It is most commonly linked to wheat and wheat products, but it can also be found in barley, triticale and rye.

Things also get a little confusing because you can get different types of wheat. Terms such as durum, spelt, kamut or emmer are names for different wheats (and therefore contain gluten). Likewise, flour typically contains wheat, as does semolina (partly made from milled wheat).

Oats are a gray area. While oats themselves don’t contain gluten, they can become contaminated if processed in the same factory that handles wheat, barley or rye.

Dietary Allergies and Gluten

Now that we know what we’re talking about, let’s go back to the argument in favor of gluten-free foods.

Remember the “wild dog” myth? It goes like this: Modern dogs can’t digest wheat, and wheat caused food allergies.

Symptoms of a Food Allergy in Dogs

So if a dog has a food allergy, what symptoms can you expect? The allergy can take 2 forms: gut-related and skin-related.

The gut symptoms include:

The skin symptoms include:

Hmm, that sounds like a good reason to steer clear. So how common are food allergies?

Experts estimate around 10% of dogs suffer from atopy, or an allergy to something in their environment. This is broad brush and includes pollens, molds, dust and food allergies.


Of the 10% that are allergic, around 10% of those are due to food allergies. In other words, only 1% dogs may suffer from a food allergy. But this is all food allergic dogs, not just those with gluten-sensitivity.

To get a feel for the stats, around 60% of food allergic dogs react to beef, as compared to 25% who react to wheat. So only around 0.25% of dogs (or 1 out of every 400 dogs) might have a wheat allergy.

Grain-Free Dog Food and Heart Problems

The FDA is investigating a possible connection between certain pet foods containing peas, lentils, other legume seeds or potatoes as main ingredients and DCM, a serious form of heart disease in dogs.3

Here are some important things to know at a glance:

  • The number of cases is small.
  • There are no recalls of any pet foods yet due to any potential link to DCM.

The Story of Peanut, a Beagle–Lab Mix

In 2018, Tuft’s University went public with the story of Peanut, a 4-year-old Beagle–Labrador Retriever cross.

Peanut presented in heart failure. Not only is it unusual at such a young age, but the parent breeds are not usually linked with heart disease. To top things off, Peanut wasn’t suffering from valvular heart disease but from an unusual weakness of the heart muscle that meant his heart had enlarged (dilated cardiomyopathy, or DCM).4

Every aspect of Peanut’s life was analyzed. It transpired that his humans had fed him a grain-free diet in the belief they were giving their dog the best. Peanut’s heart was supported with medications, and the people changed him to a regular diet.

Five months later, Peanut’s heart was nearly back to normal. This was even more extraordinary because once DCM sets in, it’s not usually reversible even with medication.

Click the image above to see the FDA’s full letter from July 2018.

An FDA Warning

But Peanut isn’t a standalone case.

So much so that in July 2018, the FDA issued an alert. This raised awareness of unusually high incidence of DCM in dog breeds not normally linked to this condition.

What these sick dogs all had in common was that they had been fed certain grain-free diets. Instead of using wheat, barley or rye as a source of carbohydrates, these foods used alternatives such as potato, lentil or chickpea flour.

According to the FDA:

“There is a range of different brands and formulas included in the reports. Rather than brands, the common thread appears to be legumes, pulses (seeds of legumes) and/or potatoes as main ingredients in the food. This also includes protein, starch and fiber derivatives of these ingredients, (e.g., pea protein, pea starch or pea fiber).”

The FDA cautions that “grain-free” doesn’t automatically mean “bad.” What it really seems to come down to is how much legumes or potatoes the dog food contains.

“High levels of legumes or potatoes appear to be more common in diets labeled as ‘grain-free,’ but it is not yet known how these ingredients are linked to cases of DCM,” the agency says. “Additionally, legumes and potatoes may appear as ingredients in foods that are not labeled as ‘grain-free.'”5


Again, not all grain-free dog food formulas are implicated. The problem appears to be with certain dog foods that are heavy in peas, lentils, chickpeas or potatoes (including sweet potatoes). Taurine, basically an amino acid, is not present in vegetarian protein sources such as grains and legumes.

“It seems that many diets that are on the market have gone the route of using a high degree of legumes in their diets — things like lentils and green peas,” Dr. Joshua Stern, DVM, PhD, DACVIM, told NewsRadio KFBK in an interview.

“And they’ve put those things in combination with, frequently, novel protein sources — things like duck or pork or kangaroo. We’re not sure what it is about these combinations, but what we’re recognizing is that many dogs eating these diets are coming up deficient in some important amino acids that we can measure.”

Current thinking, as The New York Times reports, is that “legumes may interfere with [certain dog breeds’] ability to make taurine or perhaps absorb it” — but that seems to be only part of the problem.

According to the FDA, “Taurine deficiency is well-documented as a potential cause of DCM, but it is not the only cause of DCM. Nutritional makeup of the main ingredients or how dogs process them, main ingredient sourcing, processing, amount used or other factors could be involved.”

High-Heat Processing as a Possible Factor

We bolded the word “processing” above because it hits on a major point.

“The problem with [some] grain-free formulas isn’t the lack of grains,” writes Dr. Karen Becker, DVM. “It’s the high level of starchy carbohydrates coupled with the extreme high-heat processing methods used to produce these diets.”

High-heat processing (as well as transportation in hot trucks and storage in hot warehouses) is notorious for destroying nutrients in dry dog food, and Dr. Becker says, “It’s hardly surprising these diets aren’t an adequate source of taurine for many dogs.”

Exotic Ingredients and Bioavailability

“Inclusion of exotic ingredients, such as kangaroo, alligator, fava beans and lentils, adds another level of complexity to ensuring the diet is nutritious and healthy,” according to a December 2018 paper published by Dr. Stern and others.6

The paper explains that “exotic ingredients have different nutritional profiles and different digestibility than typical ingredients and have the potential to affect the metabolism of other nutrients. For example, the bioavailability of taurine is different when included in a lamb-based diet, compared with a chicken-based diet, and can be affected by the amount and types of fiber in the diet.”

Golden Retrievers in particular may have trouble producing taurine at healthy levels. Photo: MISS_SUMMER

Understanding DCM in Dogs

Dilated cardiomyopathy is the second most common type of heart problem found in dogs.

This disease of the heart muscle is characterized by enlargement of the organ, usually more on one side than the other. When the heart becomes enlarged, it can no longer pump blood as efficiently as it used to.

Thinning walls in the ventricles means a decrease in pumping ability can cause fluid buildup in the lungs or belly, or both, as a result of congestive heart failure.

As the condition progresses, dogs may develop symptoms like:

  • Decrease in activity
  • Lethargy
  • Disinterest in eating
  • Weight loss
  • Rapid breathing
  • Cough
  • Distended abdomen
  • Reluctance to lie down
  • Difficulty getting comfortable
  • Fainting

Dogs presenting with these symptoms, whether or not they’ve been eating grain-free diets, should be examined by a veterinarian as soon as possible.

Is Your Dog at Risk?

Dogs ages 4 and older, as well as large or giant breeds weighing 30 pounds or more, may be at greater risk for DCM, regardless of diet, and certain breeds have a genetic predisposition, such as:

  • Afghan Hounds
  • Boxers
  • Burmese Mountain Dogs
  • Cocker Spaniels
  • Dalmatians
  • Doberman Pinschers
  • Golden Retrievers
  • Great Danes
  • Irish Wolfhounds
  • Newfoundlands
  • Old English Sheepdogs
  • Portuguese Water Dogs
  • Saint Bernards
  • Schnauzers
  • Scottish Deerhounds
  • Springer Spaniels

According to Dr. Stern, Golden Retrievers in particular may have trouble producing taurine at healthy levels.

This could partly explain why some of the dogs on grain-free diets wound up showing symptoms of DCM. If taurine production is already low and some components of popular grain-free foods interfere with taurine production or absorption, this could put these dogs at a disadvantage.

If your dog is one of the breeds above and has been eating a grain-free formula as the majority of their diet for a significant period of time, keep an eye out for the symptoms of DCM. See your vet if you notice any signs of the condition.

Suspected cases are confirmed by a physical examination and heart tests.

The gold standard for detecting DCM is an ultrasound heart scan. So much so that some breeds, such as Dobermans and Saint Bernards, which are known to be genetically predisposed to DCM, should be routinely scanned once a year when over the age of 2.

In those breeds prone to DCM, prompt treatment in the early stages with pimobendan can greatly extend life. But untreated, this is a serious, life-shortening heart disease that leads to incapacity and sudden death.

Be diligent about choosing high-quality food no matter what type of diet your dog consumes. Photo: Chiemsee2016

What to Do to Avoid DCM in Your Dog

Continuing to feed your dog a grain-free diet doesn’t mean dooming your pooch to a future of heart problems. You need to be diligent about choosing high-quality food no matter what type of diet your dog consumes.

To reduce the potential risk of DCM, check the ingredients on the grain-free food you prefer to feed your dog.

Formulas with potatoes, beans or legumes high on the ingredient list are the types implicated in the FDA’s report, and some vets are also recommending that you avoid “exotic proteins” like buffalo, kangaroo and wild boar because these ingredients haven’t been evaluated as thoroughly as more common protein sources.

Look for high-quality dog foods without processed ingredients, and be discerning about the processing (and high heat) used in grain-free formulas.

Writing in response to the FDA alert, Dr. Becker says, “Until there is much more information … I recommend all dogs be supplemented with high-taurine foods, regardless of their current diet.”

She adds: “An easy way to do this is to simply mix a can of sardines into your pet’s meal once a week.”

If your dog shows signs of a food allergy, then it’s best to talk things over with an understanding vet. Switching protein sources (for example, from beef to chicken) may be a better option than gluten-free. Actual health problems caused by gluten are much lower than you’d believe from browsing the pet store shelves.

Grain-Free Dog Food and Heart Problems: Frequently Asked Questions

What is DCM?Dilated cardiomyopathy (DCM) is a serious form of heart disease in dogs. Some dog breeds that aren’t typically genetically prone to DCM are getting it — and apparently most of those dogs were fed “grain-free” diets.
So what’s going on here?There might be a link between DCM and dogs eating certain dog foods containing legumes like peas or lentils, other legume seeds, or potatoes (including sweet potatoes) as main ingredients.
Do we know what it is about these dog foods that may be connected to DCM?“At this time, it is not clear what it is about these diets that may be connected to DCM in dogs,” says the FDA. “Taurine deficiency is well-documented as a potential cause of DCM, but it is not the only cause of DCM. Nutritional makeup of the main ingredients or how dogs process them, main ingredient sourcing, processing, amount used or other factors could be involved.”
Have there been any pet food recalls due to a DCM link?No. (Here’s the list of all U.S. dog food recalls, which we regularly update.)
Is all grain-free dog food bad?No. In fact, the FDA specifically says “grain-free” doesn’t automatically mean “bad.” What it really seems to come down to is how much legumes or potatoes the dog food contains. (Are peas, lentils, chickpeas or potatoes the “main ingredients” in the dog food?) To complicate things further, sometimes these diets also include “exotic” proteins like duck, pork or kangaroo, and that combination may be problematic, too. In addition, high-heat processing of the dog food may be a factor. There’s a lot we don’t know, unfortunately.
Does this possible DCM link include dog foods with rice?Per the FDA, rice is a grain, not a legume. The current reports do not suggest there is any link between diets with rice and DCM in dogs.
Should I change my dog’s diet?“At this time, we are not advising dietary changes based solely on the information we have gathered so far,” says the FDA. “If you have questions or concerns about your dog’s health or diet, we suggest that you consult your veterinarian for individualized advice that takes into account your dog’s specific needs and medical history.”
Talk with your veterinarian for individualized advice if you’re concerned about your dog’s diet. Photo: Pixabay

So, What Next?

We still have frustrating little information here.

Even the FDA concedes it doesn’t have any “definitive answers” yet.

“The common thread seems to be legumes and/or potatoes as main ingredients in the food,” says Anne Norris, a Center for Veterinary Medicine health communications specialist. She added: “Currently, it’s a correlative link, not a causative one.”7

If your dog has already shown signs of DCM, or if you’re at all concerned, take the advice of your vet regarding dietary changes, medications and potential taurine supplementation.


  1. Czupryna, Anna M., PhD, et al. “Ecology and Demography of Free-Roaming Domestic Dogs in Rural Villages near Serengeti National Park in Tanzania.” PLoS One 11, no. 11 (Nov. 28, 2016): e0167092.
  2. “Gluten-Free Diet.” Mayo Clinic. Nov. 23, 2017.
  3. Freeman, Lisa M., DVM, PhD, DACVN. “A Broken Heart: Risk of Heart Disease in Boutique or Grain-Free Diets and Exotic Ingredients.” Cummings Veterinary Medical Center at Tufts University. June 4, 2018.
  4. Nelson, O.L., DVM, MS, Dip ACVIM. “Dilated Cardiomyopathy (DCM).” Washington State University College of Veterinary Medicine.
  5. “Questions & Answers: FDA Center for Veterinary Medicine’s Investigation Into a Possible Connection Between Diet and Canine Heart Disease.” U.S. Food and Drug Administration. Aug. 10, 2018.
  6. Kaplan, Joanna L., DVM, et al. “Taurine Deficiency and Dilated Cardiomyopathy in Golden Retrievers Fed Commercial Diets.” PLoS ONE 13, no. 12 (Dec. 13, 2018): e0209112.
  7. Phillips-Donaldson, Debbie. “FDA Dog Food Warning Hasty, Too Focused on Ingredients.” Petfood Industry. July 23, 2018.
vet-cross60pThis pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS, with contributions from Petful publisher Dave Baker, a journalist and editor who has been closely tracking U.S. pet food recalls and safety for the past decade. This article was last reviewed and updated Jan. 24, 2019.

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