Diet-Associated Dilated Cardiomyopathy in Dogs: From Grain-Free Diets to Cellular Biology (Part 1)

How Our Understanding of Nutritional DCM Has Evolved—and What We Know in 20026

By Christina Bové, DVM, MS, DACVIM (Cardiology)

Over the last decade, few topics in veterinary cardiology have generated as much discussion—and controversy—as diet-associated dilated cardiomyopathy (daDCM).

What initially appeared to be a straightforward question—

"Are grain-free diets causing heart disease?"

—has evolved into one of the most fascinating and rapidly changing areas of veterinary medicine.

Today, our understanding extends far beyond grains. Emerging evidence suggests that diet-associated DCM is likely a complex, multifactorial disease involving nutrition, metabolism, genetics, and cellular biology.

Although many questions remain unanswered, one thing is clear:

The conversation has changed dramatically since 2018.

Why Diet-Associated DCM Matters

Dilated cardiomyopathy (DCM) is a serious disease characterized by:

• Enlargement of the heart chambers

• Reduced contractility

• Progressive heart failure

• Ventricular arrhythmias

• Increased risk of sudden death

Unlike many inherited cardiomyopathies, some cases of diet-associated DCM appear to be partially—or even dramatically—reversible following dietary modification and appropriate cardiac therapy.

That possibility of recovery is what makes this disease so important.

Early recognition may improve:

• Cardiac function

• Quality of life

• Long-term survival

Because of this, understanding the relationship between nutrition and heart disease has become increasingly important for veterinarians and pet owners alike.

Traditional Dilated Cardiomyopathy

Historically, DCM was considered primarily a genetic disease affecting breeds such as:

• Doberman Pinschers

• Great Danes

• Irish Wolfhounds

• Boxers

• Newfoundlands

• Portuguese Water Dog

• Cocker Spaniel

These dogs typically develop progressive myocardial dysfunction because of inherited abnormalities.

For decades, veterinary cardiologists viewed DCM largely through a genetic lens.

Then something unexpected happened.

Unexpected Breeds Began Appearing

Beginning around 2014–2015, cardiologists started seeing DCM in dogs that traditionally were not considered predisposed.

Examples included:

• Golden Retrievers/Goldendoodles

• Labrador Retrievers/Labradoodles

• Miniature Schnauzers

• Shih Tzu

• Yorkshire Terrier

• Other Mixed-breed dogs

• Other small-breed dogs

Even more intriguing, many of these dogs improved after changing diets.

This observation immediately raised an important question:

Could nutrition contribute to heart disease in some dogs?

The FDA Investigation Changed Everything

In July 2018, the U.S. Food and Drug Administration (FDA) announced an investigation into a possible relationship between canine dilated cardiomyopathy and certain diets.

Many affected dogs reportedly consumed foods containing:

• Peas

• Lentils

• Chickpeas;

• Potatoes

• Other legumes and pulse ingredients.

The FDA emphasized that the issue appeared complex and that causation had not been established.

Nevertheless, the announcement generated tremendous public attention.

Suddenly, veterinarians, breeders, nutritionists, and owners were asking:

"Are grain-free diets causing DCM?"

The Grain-Free Era

Because many reported cases involved grain-free foods, the term "grain-free DCM" quickly entered both veterinary and public discussions.

Later, another term emerged:

BEG Diets

Boutique
Exotic ingredient
Grain-free

These terms were useful initially because they helped identify common characteristics among many diets involved in early reports.

However, as more research accumulated, the limitations of these labels became increasingly apparent.

Why We No Longer Use the Term "Grain-Free DCM"

Current evidence suggests that the disease is far more complicated than simply the absence of grains.

Investigators recognized several important observations:

• Not all affected dogs ate grain-free diets

• Some dogs improved after switching from one grain-free diet to another

• Home-prepared and unconventional diets could also be involved

• Multiple dietary patterns appeared capable of producing similar disease

Even in the original review by Freeman and colleagues in 2018*, the authors emphasized that causation had not been established and that multiple factors were likely involved.

As our understanding evolved, many cardiologists moved away from terms such as:

• Grain-Free DCM.

• BEG diets.

*https://avmajournals.avma.org/view/journals/javma/253/11/javma.253.11.1390.xml

Instead, most experts now prefer:

Diet-Associated Dilated Cardiomyopathy (daDCM)

or

High-Pulse Diet-Associated DCM

These terms better reflect what we currently know—and what we still do not know.

What Are Pulses?

One of the biggest conceptual shifts in recent years has been the focus on pulse ingredients.

Pulses are the edible seeds of legumes and include:

• Peas

• Lentils

• Chickpeas

• Split peas

• Dry beans

Pet food manufacturers may also use pulse fractions such as:

• Pea protein

• Pea fiber

• Pea starch

• Lentil flour

• Chickpea protein

Because these ingredients can be separated into multiple components, a single plant may appear several times on an ingredient list.

For example:

• Peas

• Pea protein

• Pea fiber

• Pea starch

All may originate from the same ingredient source.

Pulse Burden May Matter More Than Grain Status

Current evidence increasingly suggests that the overall pulse burden ("pulse dose") may be more important than whether a food contains grains.

This represents one of the biggest changes in thinking over the last decade.

Instead of asking:

"Is this food grain-free?"

Many cardiologists now ask:

"How pulse-rich is this food?"

The answer may depend on:

• The number of pulse ingredients present

• The use of pulse fractions

• Ingredient placement on the label;

• Duration of feeding

• Individual susceptibility

Importantly, this does not mean that peas, lentils, or other pulse ingredients are inherently harmful. Many dogs consume diets containing these ingredients without developing heart disease, and current evidence does not support eliminating all pulses from canine nutrition but to avoid high pulse diets.

The disease is likely far more complicated than a single ingredient causing a single disease.

Why This Disease Is So Complex

Diet-associated DCM represents the intersection of cardiology, nutrition, genetics, and metabolism.

One of the challenges in understanding the disease is that millions of dogs consume diets containing pulse ingredients without developing heart disease, while some affected dogs experience significant improvement following dietary modification.

These observations suggest that diet-associated DCM is unlikely to be caused by a single ingredient or explained by a single mechanism. Instead, current evidence supports a complex interaction among diet composition, metabolism, genetics, and individual susceptibility.

As with many areas of medicine, our understanding continues to evolve as new research emerges.

Looking Ahead

The biggest question facing researchers today is no longer:

Are grains protective?

Instead, investigators are asking:

What metabolic and cellular pathways are being altered?

In Part 2, we'll explore:

• The history of taurine deficiency and reversible nutritional cardiomyopathies

• Why taurine deficiency does not explain most modern cases

• Metabolomics and foodomics research

• The emerging concept of pulse burden

• Feeding trials that helped change our understanding of the disease

• Evidence suggesting that measurable cardiac changes may occur within weeks—not years

As it turns out, the story becomes even more interesting from there.