Exploring the myths: Grain Free Diets and DCM PART ONE

Dog watching his food being poured into a dog bowl

Disclaimer: These blog posts are based entirely on my personal opinions, experience and (general) research. I am not involved with the FDA report in any way or affiliated with any of the brands of dog food discussed in these articles. My intention in writing these posts is to share my opinions how to best feed and care for your animals in light of this developing story.

Part ONE Exploring the myths: Grain Free Diets and DCM

Part TWO Changes in Grain Free diets: Could these be causing DCM?

I have also put together a PDF available for download that includes my recommendations on dog foods, supplements and what to feed your pets in light of these recent DCM controversies (COMING SOON)

I am a veterinarian who has recommended Grain Free diets for pets for over a decade now. I have done this, as I explained in this blog series, because I saw many health improvements in my patients that were eating these diets over conventional diets with grains in them.

As I said in my previous posts, I have no problem with grains themselves, but more with the problematic grains traditionally included in pet food. I worry about the high glyphosate (Roundup) and pesticide use in ingredients such as corn, soy and wheat, and how these contaminants might be having negative health impacts on both people and our pets.

And while the Grain Free diets were, and are not perfect, I still feel that they are a step in the right direction.

At the same time, I was equally concerned last year when I heard about Grain Free diets being possibly linked to recent cases of heart disease in dogs.

In the summer of 2018, the FDA issued a preliminary warning about a sudden clustering of incidences of dilated cardiomyopathy, or DCM, found in dogs belonging to breeds that are not normally susceptible to this disease. Because cardiologists are aware of the connection of DCM to diet, they noticed that a large proportion of these dogs were eating grain free, and what the FDA initially called: exotic protein and boutique diets.

As with any scare, the situation quickly spiraled into a lot of panic and misinformation.

So here’s a quick rundown of what we know now, based on the most recent FDA report, that we didn’t in the summer of 2018 when this all first came to light:

Starting in 2018, the FDA received reports of dogs developing a relatively uncommon type of heart disease in dogs, called dilated cardiomyopathy, or DCM. Traditionally, DCM has been linked to nutritional deficiencies in the diet for cats and dogs and in particular linked to inadequate amounts of the amino acid: taurine.

It seemed that the majority of the dogs affected in these new complaints to the FDA (91%) were eating grain free diets, and so many people are suspecting a dietary cause.

What is going on?

I decided to write this blog post in two sections.

In this part, I tackle some of the common misconceptions about this situation.

In part 2, I look at what actually is happening, and more importantly, how grain free dog food has changed in the past few years.

Let’s begin by taking a look at what we know today, that we did not know when this all first came to light in the summer of 2018.


Because of the name: Grain Free, many have jumped on the idea that the lack of grains is what is causing the DCM.

As I explained in this blog post here, the Grain Free name is more of a distinction between two corporate players and philosophical differences on ways of feeding.

It is unlikely that the lack of grains such as corn and wheat would be causing this problem.

For one, grains grains do not contain either taurine or carnitine, which are the nutrients needed to support the heart and prevent DCM, or dilated cardiomyopathy.

Furthermore, one type of grain, rice, has actually been shown in studies to decrease the taurine concentrations in the body and pull it out in the feces.

Dogs have no inherent need for grains or any carbohydrate. This was shown in studies as far back as the 1970s (p.291 NRC).

Some dogs who were affected with dilated cardiomyopathy were subsequently switched to another grain free diet and were able to reverse the disease without the addition of any grains.

91% of the dogs that developed DCM were eating Grain Free diets. However, 9% were eating diets with grains in them and still developed the disease. The lack of grains was not protective in any way.

It is more likely that the disease is related to the high legume content of many Grain Free diets. Some Grain Free diets use legumes (peas and lentils) as their carbohydrate source, and in recent years, companies have actually increased the legume content in many of the diets.


A lot of the initial articles were targeting the idea (based on the initial FDA reports) that this was related to exotic proteins and boutique diets. It turns out from the recent reports, that the most common proteins found in the diets in question were (in descending order) chicken, lamb, salmon, white fish and then followed by kangaroo.

However, after closely examining the exact diets that the dogs were eating in the FDA complaints, I can understand why “exotic proteins,” and in particular, kangaroo, was thought to be a problem. More on this topic in the next blog post of this series.

While chicken was the highest offender according to the FDA report, it is likely that chicken is over-represented because it is the most common ingredient in dog food. Lamb is more likely to be a problem. It is a low taurine meat and has been implicated in DCM cases going back as far as 2003.

However, lamb is not exactly an “exotic” protein when it comes to dog food.

Purina, considered one of the largest pet food companies in the world, has used lamb in its formulas going back as far as 2001 (probably even before this, but this is one mention I found of it using the internet archive website: WayBack machine).*

Purina dog food

*Two dogs in the recent DCM complaints (2018 – 2019) were eating Purina’s Lamb and Rice formula.

Lamb is not an exotic protein in dog food. Chicken is also not an exotic protein in dog food. Kangaroo is exotic, but its problem may be that it is low in taurine. The common denominator among these proteins is not their “exotic-ness” but rather, their taurine content when combined with other ingredients.


The name “boutique” diets implies small scale, mom-and-pop shops making their own dog food. In reality, the main dog foods implicated in this scandal, are Acana, Taste of the Wild and Zignature. Some of the corporations that owned the Grain Free diets implicated in the DCM cases include Diamond, Champion and General Mills. These are not boutique companies.

4) Not due to lack of nutritionists or improper scientific formulation

One common theory that is being circulated around the internet is that Grain Free diets caused the DCM because they are not scientifically formulated and the companies do not employ veterinary nutritionists.

Having a board certified veterinary nutritionist on staff would have likely not prevented this from happening. DCM in dogs eating legume-based diets was not a known concern for dogs.

Two of the larger grain free companies actually do employ board certified veterinary nutritionists on staff (Canine Instinct and Blue Buffalo). There are possibly more that do.

Feeding trials, the way they are conducted today, could have also easily missed problems in these diets. After all, the majority of dogs eating these diets do not develop DCM.

Feeding trials only last 6 months and require 8 animals. They also only check basic blood parameters. They do not look for heart disease.

One cardiologist actually did a small feeding trial at Ross University to look for changes in heart parameters on dogs specifically fed a high legume diet and found no heart changes or signs of DCM at the conclusion of the feeding trial period.


DCM, or dilated cardiomyopathy, is a disease that has historically been associated with lack of the amino acid: Taurine (in animals). In the 1980s, cats were developing this same heart disease (dilated cardiomyopathy) and it was found to be related to a lack of taurine in the diet. Taurine is an amino acid that is now believed to be (after these problems in the 80s) required for cats, but non-essential for dogs.

Dogs have always been believed to be able to make their own taurine as long as there is enough of its precursors, methionine or cysteine, in the diet. Some controversy still exists on this topic as certain breeds might actually need taurine (or at least more of it) in the diet than we initially thought.

However, after an initial scare that it was a lack of taurine that was causing this problem, it was revealed that a number of dogs in these recent DCM cases had normal or even high levels of taurine in their blood.

The dog foods themselves were also analyzed and all had adequate levels of methionine (the precursor to taurine) in the diet according to the FDA report and met current AAFCO nutrient recommendations.

All of the Grain Free diets implicated followed the proper guidelines and current nutrient profiles recommended for all dog food today.

In summary, we don’t know what exactly is causing the DCM in dogs affected by this problem. However, low taurine proteins combined with high legume diets may be part of the problem.

Let’s take a closer look at this now.

Click here to read PART TWO of this blog series.

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