it depends on the dog, some dogs have really sensitive tummies. my yorkie does. so i would make the switch as slowly as you possibly can. otherwise if you have a yorkie with sensitive tummy, it will take them a while to recover, and you will have to clean their runny poop for a while which really sucks.(usually if i upset my yorkie's tummy she takes a long time, like 2 weeks to start having normal stool again) so i recommend doing it as slowly as you possibly can. especially with a puppy, you will have enough to deal with all the potty training, and getting the puppy used to the new environment. sometimes just the stress of being in a new environment will cause them tummy upsets. plus it's nice for the puppy to have same food for a while i think, probably comforting to them. good luck!
