The FDA just released its third public report on the link between grain-free diets and dilated cardiomyopathy (abbreviated DCM), revealing the top brands, ingredients, and breeds associated with DCM. The most common diets associated with DCM were Acana, Zignature, and Taste-of-the-Wild (almost 50% of the cases). The most common breeds were the Golden Retriever, Labrador, and Mixed Breed (especially of larger body size), whereas previously it had been the Doberman, Great Dane, and Irish Wolfhound. Product testing did not find any nutritional deficiencies in these diets, including adequate Taurine levels. However, there appeared to be a correlation with diets containing legumes (peas, lentils, and/or potatoes) as main ingredients. The DCM appeared to improve when these patients were switched to grain-based diets.

Although the link between grain-free diets and DCM is still under investigation, 1. these studies create doubt about their safety, and 2. there is no medical benefit to feeding a grain-free diet (most pet allergies are to animal proteins rather than grain). Therefore, we recommend switching all pets, especially high risk breeds listed above, to a grain-based diet. In particular, we recommend avoiding diets with legumes (peas, lentils, and/or potatoes) as main ingredients. Consider choosing a diet from one of the few companies that actually perform feeding trials, have nutritionists on board, and are AAFCO certified: Royal Canin, Purina, and Hills/Science Diet.

If you decide to continue feeding a grain-free diet anyway (if your pet is extremely picky and/or finding the right diet has been challenging), consider testing for blood Taurine levels (one nutrient that is sometimes linked with DCM, especially in Golden Retrievers), or at least consider supplementing with Taurine at 250mg per day (safe even in healthy dogs). Just adding grain (such as rice) to a grain-free diet will not offset the risk of DCM.

Here is a link to detailed information on the FDA website:
https://www.fda.gov/animal-veterinary/news-events/fda-investigation-potential-link-between-certain-diets-and-canine-dilated-cardiomyopathy

Here is an excellent blog with more details:
https://vetnutrition.tufts.edu/2018/06/a-broken-heart-risk-of-heart-disease-in-boutique-or-grain-free-diets-and-exotic-ingredients/