Pet Nutrition

The Truth About Grain-Free Diets and Heart Disease

📅 Published December 2025 🕓 6 minute read

In 2018, the FDA made an alarming announcement: they were investigating a potential link between grain-free dog foods and a serious heart condition called dilated cardiomyopathy (DCM). The news sent shockwaves through the pet food industry and left countless dog owners confused and concerned.

If you feed your dog a grain-free diet or have considered switching, you need to understand this issue. This article breaks down what we know, what remains uncertain, and how to make informed decisions about your dog's food.

Understanding Dilated Cardiomyopathy (DCM)

Dilated cardiomyopathy is a serious heart disease where the heart muscle weakens and the chambers enlarge. As the heart muscle stretches and thins, it can't pump blood effectively. Left untreated, DCM leads to congestive heart failure and often death.

DCM has a genetic component and typically affects certain breeds:

• Doberman Pinschers
• Great Danes
• Boxers
• Irish Wolfhounds
• Saint Bernards
• Cocker Spaniels

However, veterinary cardiologists began noticing DCM in breeds not typically predisposed to the condition, including Golden Retrievers, Labrador Retrievers, and many small breeds. The common thread? Many affected dogs were eating grain-free diets.

The FDA Investigation

In July 2018, the FDA announced it was investigating reports of DCM in dogs eating certain pet foods. By 2019, they'd received over 500 reports of DCM, primarily in dogs eating "BEG" diets: foods containing peas, lentils, chickpeas, and other legume seeds (pulses), or potatoes as main ingredients.

Key Findings

The FDA's investigation revealed several patterns:

• Most reported cases involved dogs eating grain-free formulas
• Foods high in peas, lentils, other legumes, and potatoes were common
• Many affected dogs were breeds not genetically predisposed to DCM
• Some dogs improved after dietary changes and appropriate medical treatment
• Not all grain-free foods were implicated equally

However, and this is crucial: the investigation didn't prove causation, only correlation. The FDA hasn't definitively identified the specific cause or mechanism.

What Might Be Causing the Problem?

Scientists have proposed several theories about why certain grain-free foods might be linked to DCM:

Taurine Deficiency

Taurine is an amino acid essential for heart health. While dogs can typically synthesize taurine from other amino acids, some grain-free foods may interfere with this process or increase taurine excretion. However, not all affected dogs had low taurine levels, so this doesn't explain all cases.

Protein Quality and Digestibility

Many grain-free foods use plant-based proteins (peas, lentils, potatoes) to replace grains. These may be less digestible or have different amino acid profiles than traditional protein sources, potentially affecting heart health in ways not yet fully understood.

Other Nutritional Imbalances

Grain-free formulas represent a significant departure from traditional dog food recipes. It's possible that removing grains and replacing them with legumes and potatoes creates nutritional imbalances we haven't yet identified.

Manufacturing or Ingredient Issues

Some researchers suspect specific ingredient sources, processing methods, or even contamination might play a role, though this remains speculative.

The Grain-Free Marketing Myth

It's worth understanding how grain-free diets became so popular in the first place. Marketing campaigns successfully convinced many pet owners that:

• Grains are "fillers" with no nutritional value
• Dogs are carnivores that shouldn't eat grains
• Grain-free diets are more "natural" or "ancestral"
• Grains commonly cause allergies

None of these claims are accurate. Dogs have evolved to digest grains and can derive nutrition from them. True grain allergies are relatively rare, with meat proteins being far more common allergens. Grains provide beneficial nutrients, fiber, and energy.

The grain-free trend was driven by marketing, not science. Many pet owners switched unnecessarily, believing they were providing better nutrition when they may have been increasing health risks.

What This Means for Your Dog

If You Currently Feed Grain-Free

Don't panic, but do take this issue seriously. Consider the following steps:

1. Assess necessity: Does your dog have a confirmed grain allergy or medical reason to avoid grains? If not, grain-free food isn't necessary.

2. Check the ingredients: Does the food list peas, lentils, other legumes, or potatoes among the first ten ingredients? These are the foods of most concern.

3. Know your dog's risk: Golden Retrievers, Labrador Retrievers, and other breeds genetically predisposed to DCM may be at higher risk.

4. Consult your veterinarian: Discuss whether switching foods is advisable. If your dog has been on grain-free food long-term, your vet might recommend screening for heart issues.

5. Watch for symptoms: Signs of DCM include lethargy, weakness, decreased appetite, coughing, difficulty breathing, and abdominal distension. Seek immediate veterinary care if these develop.

If You're Considering Grain-Free

Unless your dog has a documented grain allergy (confirmed through an elimination diet trial), there's little reason to choose grain-free food, and there may be risks. Talk to your veterinarian before switching.

Choosing Safe, Nutritious Dog Food

Given the uncertainty around grain-free diets, what should you feed your dog?

Look for These Characteristics

• AAFCO statement: Confirms the food is complete and balanced
• Established manufacturers: Companies with nutritionists on staff and quality control standards
• Feeding trials: Foods tested through AAFCO feeding trials, not just formulated to meet nutrient profiles
• Named meat proteins as primary ingredients: Chicken, beef, fish, not just plant proteins
• Grains are fine: Rice, oats, barley, and other grains provide beneficial nutrition

Red Flags

• Heavy reliance on peas, lentils, chickpeas, or potatoes
• Exotic proteins marketed as "premium" without veterinary reason
• Boutique brands without established track records
• Claims that seem too good to be true
• "Grain-free" as the primary selling point

The Bottom Line on Grain-Free Diets

While the FDA investigation hasn't definitively proven that grain-free diets cause DCM, the association is concerning enough that pet owners should take it seriously. The potential risks outweigh the benefits for dogs without confirmed grain allergies.

Here's what we know for certain:

• Most dogs don't need grain-free food
• Grain allergies are uncommon in dogs
• Some dogs eating certain grain-free foods have developed DCM
• The specific cause hasn't been definitively identified
• Some affected dogs improve when switched to different diets

Moving Forward

The grain-free diet situation illustrates an important lesson: popular doesn't mean better, and marketing claims shouldn't replace scientific evidence. Well-formulated foods from reputable manufacturers, whether they contain grains or not, provide excellent nutrition.

If you're feeding grain-free food and your dog is healthy, don't make abrupt changes. Discuss the situation with your veterinarian. They can assess your individual dog's risk factors and help you decide whether changing foods is advisable.

If you're choosing a new food, there's little reason to select grain-free unless your dog has a documented medical need. Focus on quality ingredients, reputable manufacturers, and formulas backed by feeding trials and nutritional expertise.

Your dog's health is too important to leave to marketing trends. Base food choices on science, veterinary guidance, and your individual dog's needs. When in doubt, trust your veterinarian over the pet food aisle packaging.