Grain-free legume-heavy diets linked to 1,382 DCM heart disease cases but FDA stopped investigating

The FDA received 1,382 reports of dilated cardiomyopathy in dogs eating grain-free diets high in peas, lentils, and potatoes, including hundreds of deaths, but closed its public investigation in 2022 without identifying the causal mechanism or issuing any regulatory action. This matters because grain-free diets remain on shelves with no warning labels, pet owners who switched to grain-free believing it was healthier unknowingly put their dogs at risk of fatal heart failure, and veterinary cardiologists continue to see new cases. The problem persists because proving causation in diet-related disease requires expensive multi-year controlled feeding trials no manufacturer will fund against their own product, the FDA lacks authority to mandate reformulation based on epidemiological correlation alone, and the grain-free market represents $4+ billion in annual sales that the industry will not voluntarily shrink.