Does he only growl when he has a toy? Navarre would kind of growl and swing his head around when I would pick him up as a pup, and sometimes I was like "ok, I'll put you down" WRONG!! That's just reinforcing that when he growls he will be left alone. So, while the training will definitely help, I would also address the growling especially if it's not in a playful way. If he growls when something is being done, like picking him up, don't give in. Pick him up and hold him until he's calm and continue to hold him and love on him for a few minutes after he calms down then put him down. This especially needs to be done while he's little, which won't be for much longer!!! And if your kids can get involved in that somehow, safely, they need to be because Goliath needs to learn that he has to respect and mind them too!! Good luck!