To many of us, our pets are members of the family. As such, we extend our healthy lifestyles to our pets… this includes wanting to feed them the healthiest diet possible. There are so many different foods available, and often conflicting theories on the best diets for pets, it’s enough to make your head spin!

We spend so much time researching and reading labels, trying various food brands, and experimenting with various levels of processing. After all of this exhaustive work, we finally find a diet that our pet LOVES and one we were confident that would contribute to a longer, healthier life, but then… Just when we think we have a handle on how best to feed our pets, new information is released which leaves us back at square one… confused!

Most recently, grain-free diets were called into question. A link was suspected between these diets and a canine heart disease known as Dilated Cardiomyopathy (DCM). It was speculated that the high levels of legumes in these foods were causing a flare in cases of DCM. This has been a very controversial and confusing subject, with many vets recommending that pet parents avoid grain-free, legume-heavy diets at all costs, however, a new comprehensive study has shown that there is no evidence to support that grain-free legume-based foods are linked with heart disease. Today’s blog will discuss all of this and more!

Diets Linked to Heart Disease in Dogs-

So, what happened? Back in June 2018, a veterinary nutritionist published an article online expressing concern that that veterinary cardiologisits were seeing an increase in heart disease in dogs being fed certain diets.

The FDA then released a statement, in July 2018, that there could be a relationship between certain types of food and Dilated Cardiomyopathy (DCM). The FDA then went so far as to list the top 20 foods that had been fed to a majority of affected dogs. However, because the actual link was not determined, the FDA did not advise changing diets.

The following December, a group of cardiologists and nutritionists published an article in the Journal of the American Veterinary Association. They stated that a group of veterinary cardiologists had an impression of an increase in DCM cases recently, not only in breeds that are genetically pre-disposed to it, but in other breeds as well.

This impression involved mainly dry dog foods which were “grain-free”, contained novel protein sources (“exotic” meat sources such as kangaroo, and peas/lentils, beans as protein sources), or were mostly sold by “boutique” (smaller) manufacturers; referred to as “BEG” diets by the authors of the article. “BEG” was an acronym for Boutique pet store, Exotic ingredient, Grain-free.

How Peas & Lentils Got Involved-

The proposed theory was that by removing grains and adding in higher levels of legumes (peas and lentils), the absorption of the amino acid taurine, which is necessary for normal cardiac function, was adversely affected.

Is a Taurine Deficiency to Blame?

Taurine deficiency was previously found to be a cause of DCM in cats. Cats cannot synthesize taurine internally, so they must ingest it from their food. This was not originally understood, and their formulated diets lacked adequate levels of taurine. By simply supplementing their diets with taurine, the issue was resolved.

Dogs are different; they are known to be able to synthesize taurine from the ingredients in their food. However, some of the affected dogs were found to be deficient; others, conversely, had normal levels. The response of taurine-deficient dogs to taurine supplementation was variable. This conflicting information indicated that there were likely other factors involved other than simply a lack of taurine.

Unfortunately, a more comprehensive and thorough follow-up study was not pursued to ensure the release of more accurate data. And even though the information relayed was incomplete and not properly investigated or verified, it was enough to cause widespread concern. Although neither the article’s authors nor the FDA could identify an exact causal agent, many veterinarians immediately recommended that pet parents change diets, preferably to a grain-inclusive diet from one of the four major US pet food producers (

Many people, perhaps including yourself, were concerned that the diet they had carefully chosen for their pet was no longer considered healthy. This was a horrifying proposition, which led to panic in the veterinary community, amongst pet parents, and within the food industry itself. Panic and concern which is still in evidence today.

Why Some Vets Disagree With Grain-Free Diets-

Within the veterinary community, there is already unease over grain-free diets; many traditional vets just don’t believe in feeding pets a biologically correct diet. This is likely due to the fact that they have been educated by corporate food companies during their veterinary studies.

Pet food companies, and the industry as a whole, do perform some great research, but they don’t seem to believe in the quality of ingredients. Alternatively, many holistic veterinarians do support a grain-free approach to feeding pets, and thankfully, some level-headed veterinarians, who prefer making decisions based on science rather than fear, advised pet parents to take a deep breath and pause while we waited for some factual, verifiable information; information which was not provided by the initial report.

That information finally came along last month with the publication of an excellent scientific literature review in the June 15, 2020, Journal of Animal Science.

A panel of animal nutritionists reviewed over 150 studies involving diet and DCM and found no evidence of a link between grain-free, or BEG diets, and DCM. They also made a series of recommendations regarding further research within veterinary nutrition. If anything, this issue has highlighted how much we DON’T know about canine nutrient requirements and the complexities of ingredient interactions.

What is Dilated Cardiomyopathy and the Concern?

Before we continue on, let’s take a step back to look at DCM… what it is, and it’s causes, and then we can see how the original publication citing a link was truly not based on scientific evidence.

Dilated Cardiomyopathy, otherwise known as DCM, is a disease of the heart muscle. The lower two, more muscular heart chambers, the ventricles, progressively dilate and lose their contractile strength. This results in a heart unable to pump blood adequately, eventually leading to heart failure or failure of the pump. Abnormal heart rhythms may also develop, some of which may result in sudden death. The disease may exist for some time without clinical signs of disease. We start to see clinical signs when the heart can no longer compensate which is why a proactive approach is important.

Warning Signs of Heart Disease/DCM Include-

  • Lethargy
  • Reduced appetite
  • Exercise intolerance (shortness of breath on walks or after play)
  • Weakness
  • Fainting
  • Coughing

Because it can cause sudden death when undiagnosed, identification of the disease and preventative care is critical.

Causes of DCM include-

  1. Genetics
    • An inherited predisposition to DCM affects Boxers, Dobermans, English Cocker Spaniels, Great Danes, Irish Wolfhounds, Portuguese Water Dogs, and Newfoundlands. 
    • An inherited predisposition to taurine deficiency can lead to DCM. This is seen primarily in Golden Retrievers and American Cocker Spaniels. English Setters, Irish Wolfhounds, Newfoundlands, and Saint Bernards are also thought to be predisposed. 
  1. Myocarditis which is inflammation of cardiac muscle cells can commonly lead to DCM or heart failure. It is suspected to be an under-represented cause of DCM because it can only be confirmed by the post-mortem exam. It may be seen in patients with parvovirus infection, Lyme disease, or with infections caused by Bartonella, Nocardia or Trypanosoma species of bacteria. 
  2. Hypothyroidism can also lead to DCM by adversely affecting the contractility of the heart muscle and nerve impulses controlling heart rhythm. 
  3. Tachycardia-induced Cardiomyopathy (arrhythmia) can cause cardiac changes similar to those seen with DCM.
  4. Nutritional causes include deficiencies of protein and amino acids, vitamin deficiencies, nutrient interactions, use of thyroid-suppressive ingredients such as cassava (tapioca), soybeans, sweet potatoes, broccoli, and others), presence of heavy metals (such as those contained in fertilizers, pesticides and other chemicals used in the production of ingredients), or internal factors (such as gender, pregnancy, lactation, and presence of infection). This was the heart of the AVMA report, nutritional DCM.

What Were the Problems with the AVMA and FDA Reports?

Firstly, the publication of the AVMA article was premature and lacked scientific verification for the claims made. A causal mechanism was not established, and the numbers of dogs affected, compared to the overall population of dogs, was very small. The percentage of dogs affected was actually less than the percentage of dogs which developed DCM genetically.

There was also sample bias. The FDA requested that only DCM cases associated with the suspected diets to be reported, not all DCM cases which would provide appropriate incidence. Additionally, not every pet owner could afford the expensive tests required to diagnose DCM, which means even more pets were left out, skewing the data.

Next, was the lack of complete medical records and incomplete testing parameter requirements, which would detail the presence of any concurrent disease states that may have contributed to the development of DCM, such as hypothyroidism, Lyme disease, or other cardiac diseases such as valvular disease or arrhythmias.

Also missing were detailed dietary histories such as diet changes, length of time eating the current diet, and lists of treats or supplements. Interactions of certain dietary ingredients are known to change nutrient absorption and can cause DCM.

As you can see, there was a lot of critical information missing from this publication.

Other problems: Conflicting Data on “BEG” diets-

Another cause for concern was that the data submitted to the FDA conflicted with the claim that BEG diets were to blame for the issue.

The claim that boutique diets were the main culprit of DCM was refuted by the fact that almost half (49%) of the brands listed were manufactured by one of the 6 largest pet food producers in the US.

The claim that the main protein source was “exotic” was proven unfounded as the top 7 proteins in most (76%) of the implicated diets were chicken, turkey, beef, pork, lamb, salmon, and whitefish, hardly exotic ingredients.

Finally, past studies do not support that grain-free diets lead to DCM. For example, one study found that a whole grain diet actually caused taurine deficiency, and another showed that a 45% legume (peas, lentil) diet did not alter taurine levels.

Conflicts of Interest at Play-

Lastly, there were conflicts of interest involved with the original report as three of the five authors of the AVMA article had connections to MARS’ Royal Canin, Hill’s, and Nestle’s Purina, the companies whose foods were deemed safe, even though some diets manufactured by these companies were included in the FDA list. In contrast, there are no conflicts of interest listed for the authors of the literature review published in June. 

Should You Get Your Pet Screened for DCM Now?

If your pet’s breed, whether purebred or mixed with, is one that is pre-disposed to DCM or taurine deficiency, or you are at all concerned about your pet’s health status, you should schedule an examination/consultation with your veterinarian, regardless of what you have been feeding your pet. You can use the following checklist as a guideline:

  1. Book an appointment to have your dog screened for DCM.
  2. Ask your vet to examine your pup and listen to their heart, checking for a murmur and for any abnormal rhythm, during their full exam.
  3. Ask your vet to measure your pet’s blood taurine levels. Whole blood sampling may be more accurate than plasma sampling.
  4. Have them screen for heart disease with a NT-proBNP blood test (it measures the presence of a hormone released by cardiac muscle cells when they are stressed or stretched), or schedule an echocardiogram (basically an ultrasound of the heart and how DCM is diagnosed) to assess cardiac structure and function.

If your pup is diagnosed with DCM, taurine deficiency or both, follow your veterinarian’s recommendations. Taurine supplementation will likely be recommended. Further diagnostics will likely also be recommended to rule out infectious disease, hypothyroidism and cardiac arrhythmias. 

What to Feed Your Dog-

If your pet is not of a breed with a predisposition to either issue, there is no evidence supporting a need to change her current diet.

So, what do you do if your vet suggests changing to a grain-inclusive dry food? First, make sure she is up to date regarding current information about the above literature review. She may simply not be aware of the fact that there is currently no evidence to suggest that grain-free diets, with high legume content, are a cause of DCM in dogs.

If your vet remains tied to whole grain kibble, ask her why? Ask how s/he feels about processed food for people. Discuss your views and concerns. See if you can come to a solution together as it should be acceptable to feed a minimally processed diet. This could involve home-cooked diets, dehydrated diets, or perhaps raw food diets. If your vet is not flexible, you can always get a second or third opinion.

Ideal Diet for Pets-

Feeding a minimally processed, wholesome, balanced, and varied diet is critical. Variety and rotation of ingredients is recommended for humans AND animals to help to avoid deficiencies and excesses and to provide diverse nutrients. Consistently feeding dogs the same diet every day has been suggested as a contributing factor to taurine deficiency and DCM, since some foods are deficient not only taurine, but it’s building blocks.

Our pets’ diets should not only contain muscle meat, but also organ meat. They should contain a variety of fruits and veggies. Some carbohydrate sources are ok too. Always use a vitamin-mineral supplement if cooking for your pet to ensure adequate calcium and phosphorus levels, as well as other nutrients, just as you would take a daily vitamin supplement to ensure you are meeting your body’s daily needs.

Dehydrated diets, such as the Honest Kitchen, are great and super easy to prepare – just add water, and they are ready within 5-10 minutes. Use code WELCOME15 for 15% OFF your first order!

Pre-made raw food diets, such as Nature’s Variety, are complete diets, and their batches are rigorously tested for bacterial contaminants. The Farmer’s Dog will also deliver fresh food diets formulated with veterinary nutritionists directly to your home.

Take 50% OFF Farmer’s Dog here.

Educational Sessions on DCM & Biologically Correct Diets-

If you are looking to change your pet’s diet but your vet seems unsupportive of your desire to feed your pet a more biologically correct diet, our parent company Organic Bunny does offer educational consultations on this topic and we would love to help you make the best choices possible for your pet! To book an educational session with our licensed vet, click here.

In general, we believe that, just as processed diets are unhealthy for human beings, they are also unhealthy for our pets. Processed diets are known to be inflammatory for humans so with similar digestive and immune processes, it only follows that this would be true for our pets as well. 

What About Cats?

This issue has not been reported to affect cats at this time. 


In conclusion, there is currently no evidence to suggest that a grain-free diet, with or without high legume content, is a cause of DCM in dogs. Remember, when it comes to caring for your pet, you are her or his best advocate.

There is so much information and research available; always do your homework and discuss any concerns or questions with your vet. If you have further questions regarding this issue, you can always schedule a general, informational session with us here.

*No medical advice can be provided for your specific pet; this is a general, educational consult only.

Dr. Kristen Colleran, DVM