In 2018, the FDA began investigating a potential link between certain dog foods and dilated cardiomyopathy (DCM), a serious heart condition. The investigation sparked widespread concern about grain-free diets, leading many pet owners to question their food choices. But what does the science actually tell us?
This article examines the FDA investigation, current research, and practical guidance based on evidence rather than fear.
What Is DCM?
Dilated cardiomyopathy is a disease of the heart muscle where the heart becomes enlarged and weakened, reducing its ability to pump blood effectively. In dogs, DCM can be:
- Hereditary: Certain breeds (Doberman Pinschers, Great Danes, Boxers, Irish Wolfhounds) are genetically predisposed
- Non-hereditary (nutritional): Potentially related to diet, which is what the FDA investigated
The key difference: dogs with hereditary DCM typically cannot be cured, while dogs with nutritional DCM often improve or fully recover when their diet is changed.
The FDA Investigation: Timeline and Findings
What Happened
- July 2018: FDA announces investigation into reports of DCM in dogs eating certain diets
- 2018-2020: Majority of case reports submitted during this period
- January 2014 - November 2022: FDA received 1,382 total DCM reports
- December 2022: FDA ends routine public updates, stating no causal link established
Key Observations from the Data
The FDA noted several patterns in the reported cases:
- Legume-heavy diets: Most associated diets had legume seed ingredients (peas, lentils, chickpeas) high in their ingredient lists
- Not just grain-free: Both grain-free AND grain-containing formulations were associated with reports
- Breeds not typically affected: Many cases occurred in breeds not genetically predisposed to DCM
- Decreasing reports: Case reports dropped significantly after 2020, with only 255 cases reported between July 2020 and November 2022
What the FDA Concluded
The FDA explicitly stated: "While adverse event numbers can be a potential signal of an issue with an FDA regulated product, by themselves, they do not supply sufficient data to establish a causal relationship."
In other words: there's a pattern worth investigating, but no proven cause-and-effect relationship has been established.
Current Scientific Understanding
What Research Suggests
Ongoing studies since the FDA's investigation have provided some insights:
- Peas and lentils appear significant: High levels of legumes in the diet seem to be the strongest predictor for diet-associated DCM
- Multiple compounds investigated: Researchers are studying various mechanisms, including taurine levels, fiber interactions, and anti-nutritional factors
- Reversibility is key: Many dogs with diet-associated DCM show significant improvement when switched to different diets, suggesting a nutritional rather than genetic cause
What We Still Don't Know
Despite years of research, several critical questions remain unanswered:
- The specific mechanism: How exactly might certain diets cause DCM?
- Which ingredients are problematic: Is it legumes specifically, the absence of grains, or something else entirely?
- Risk factors: Why do only some dogs on these diets develop DCM?
- Dose-response relationship: How much of a problematic ingredient causes issues?
Practical Guidance for Pet Owners
Don't Panic
The absolute risk of diet-associated DCM remains low. Even at the peak of reported cases, the number represented a tiny fraction of the millions of dogs eating grain-free diets. This doesn't mean there's no concern—it means the risk is not as dramatic as headlines suggested.
Consider Variety
One evidence-based approach is dietary variety:
- Rotate between different protein sources
- Consider foods with diverse carbohydrate sources (not just peas/lentils)
- Don't rely solely on one formula or brand indefinitely
Evaluate Your Current Food
Look at your dog food's ingredient list:
- Multiple legumes in top ingredients? Consider alternatives
- Legumes are the primary carbohydrate source? Variety might be wise
- Your dog is a breed predisposed to DCM? Extra caution is warranted
Watch Your Dog
Regardless of diet, know the signs of heart disease:
- Decreased energy or exercise intolerance
- Coughing (especially at night or after activity)
- Rapid or labored breathing
- Fainting or collapse
- Distended abdomen
If you notice these signs, consult your veterinarian immediately.
Consult Your Veterinarian
The FDA's official recommendation remains: work with your veterinarian, who may consult with a board-certified veterinary nutritionist, before making significant diet changes.
The Grain-Free Myth
One important clarification: "grain-free" itself is not the problem. The FDA investigation found that the pattern was more strongly associated with legume content than the absence of grains.
A grain-free diet that uses sweet potatoes, tapioca, or other non-legume carbohydrates may pose different considerations than one heavily reliant on peas and lentils. Similarly, some grain-inclusive foods also contained high levels of legumes.
The marketing term "grain-free" has become a proxy for concern, but the actual nutritional composition matters more than the label claim.
Breeds at Higher Risk
While diet-associated DCM has been reported in many breeds, certain dogs may warrant extra attention:
Breeds Genetically Predisposed to DCM
- Doberman Pinschers
- Great Danes
- Boxers
- Irish Wolfhounds
- Newfoundlands
- Scottish Deerhounds
- Cocker Spaniels
For these breeds, working with a veterinary cardiologist and being particularly thoughtful about diet is advisable.
Breeds Overrepresented in Reports (Non-Traditional DCM Breeds)
- Golden Retrievers
- Labrador Retrievers
- Mixed breeds
The appearance of these breeds in DCM reports was notable because they don't typically develop hereditary DCM.
The Bottom Line
The grain-free/DCM story is a case study in how nutritional science works—slowly, with uncertainty, and rarely with clear-cut answers.
What we know:
- Some dogs developed DCM while eating certain diets
- There's an association with legume-heavy formulations
- Diet-associated DCM can often be reversed with diet change
- No definitive causal mechanism has been identified
What to do:
- Don't make fear-based decisions—evaluate your specific situation
- Consider dietary variety, especially regarding carbohydrate sources
- Monitor your dog for signs of heart disease
- Work with your veterinarian for personalized guidance
The FDA has not recalled any dog foods or advised against grain-free diets broadly. They've encouraged continued research and veterinary consultation. That measured approach is worth emulating.