Though grain-free diets for dogs have frequently popped up on store shelves, you should avoid feeding your dog a grain-free diet except under the direction and care of your vet. An FDA investigation into 515 dogs diagnosed with dilated cardiomyopathy (DCM) found 90% of them were fed a grain-free diet. Some breeds are genetically predisposed to DCM, but veterinary cardiologists have noted an increase in DCM diagnoses in breeds without a genetic predisposition. If your veterinarian feels a grain-free diet is appropriate for your dog based on other health factors, they should monitor them closely for signs of DCM.