Your breeder is probably right, the jagdterrier is one badass dog. My breeder has around 15 jagdterrier for personal use/hunt. My dog get along with my 2 other dogs but he can be a little agressive agains other unknown dogs. I have worked very much with his obedience-training. His lust for hunting seems almost endless. He pretty much wants to kill every other animal. At home he's very calm and pleasant, but in the woods he's a monster....