Ok so I'm switching the cats to Felidae tonight but I'm pretty much out of the old food. Is that gonna be a big problem? Will they get diarrhea? or vomit? If we but another bag of Purina then I can't switch them for a while and I have been asking Dad to switch for a week (at the time that I had plenty of food for the switch)and today he finally decides we can go, when we are out of the old food
so will it work out ok?