I believe it is important not to start a fight with a pup in the presence of sheep. Be it a young pup or a adolescent dog seeing sheep for the first time I want to be sure NOT to correct any barking or pulling with sheep in front of them. They are excited & keen to the action and I don't want anything to squelch their enthusiasm . Rather, I want to see their enthusiasm maintained. The obnoxious behaviors we sometimes see when they are young will go away if they have regular time with sheep. Don't worry about it. I fear more a misguided correction may cause anxiety, worry, or teach the dog not to hear me when sheep are present. None of which I want in my dog.