GSD's do tend to have sensative tummies but if you are feeding the same food it shouldn't be too bad.
Are you talking loose stools? or watery? Is your pup able to hold it or is it explosive?
I know when I walk my dogs alot they poo more and it's looser. It's the watery/explosive poos that are bad news in my house. Not so much the thick brownie batter type results.
But that's my dogs.
Did you talk to your breeder and see what their experiences are? Plus they should be able to immediately check with the other puppy owners to compare and see if there is an issue.
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