Hi.  I just got a Rat Terrier mix puppy.  His name is Tucker and he is about 12 weeks old; I got him at 6 weeks.  He is doing well with potty training, but is exhibiting some dominant traits.  When he is at home with me, his behavior is fine, but when my sister watches him, he growls and tries to bite her young children.  What can I do?  I am with her kids (ages 1, 2 and 3) a lot and I want to be able to include Tucker on our outings.  We are in puppy training class and I know that terriers can be territorial.  He also only seems to display this trait toward other males, either dog or human.  Help!

Welcome to the forum!  You might want to copy/paste this post as a new topic in the Training Forum where our training moderator, Nora, will likely see it.  Also there are numerous topics on that forum dealing with this very topic.  Look at the last 2-3 pages as this stopic of growling/biting small children has come up very recently.