you would be better off with back to basic there has never been a problem with this dog food and you can buy it direct at www.backtobasic.com plus you will always have firm stools also I would give nutri-cal since they have been so sick be careful when feed snacks as they may have an ingredent that has been causing this plus your dog will love this food you will be shock and best part no loose stools or smelly ones and just give it to him right away you don't need to mix old food with new trust me he will eat it like as if he always had it