New Food
Im getting the impression from their reviews, a number of new users aren't transitioning their dogs over a few weeks when changing foods, and just giving them a bowl, which they duly scoff.
Of course a dog will get the runs, or become unwell. They need to change food gradually, mixing old with new until its 100% new..... 80/20, 70/30, 50/50, 30/70, 10/90.......over 2 weeks!