Jessica, I went through this with my male whippet puppy from 8-10 weeks old. It was *dominance* not aggression. And yes, he was establishing his place in the pack. My daughter was the only one he felt he could be above and being a fairly dominant puppy, he would bite her and he wasn't kidding. I know what I did, but, wouldn't suggest it to someone who doesn't know what they were doing. Maybe Jim Garvie can help out as he has Rotties as his breed