How canine heart disease was tied to grain-free dog food

Dog food is shown in a pet store in Westfield, Ind., Tuesday, July 19, 2022. In 2018, the FDA began investigating whether the increasing popularity of grain-free dog foods had led to a sudden rise in a potentially fatal heart disease in dogs. Four years later, the FDA has reached no conclusion, but the publicity surrounding the issue has shrunk the once-promising market for grain-free dog foods. (AP Photo/Michael Conroy)