[Sanne]

Was it liquid or just a bit soft? It’s not uncommon for sensitive dogs to have a soft stool or two after having something new introduced. If it was just soft you could still try adding a small amount to his regular food to see if he gets used to it. Soft stool is nothing to be too worried about when trying something new. You need to give it about week to let his system get used to it. If the stool is watery/liquid then yes I would discontinue the new food completely and not bother with it