Whether the U.S. Food and Drug Administration (FDA) realized it or not, their recent warning letter (July 12, 2018) regarding dilated cardiomyopathy (DCM) in dogs has implicated all grain-free diets, not just those fed to dogs suffering from this disease. The implication that all diets containing legumes and tubers are somehow suspect is a big stretch, but that is how the market is reading it.
Don't panic yet about peas and potatoes in dog food diets
There is likely more to the canine dilated cardiomyopathy story than the current focus on only grain-free pet foods would suggest.