Hi, I have a 14 week old Tibetan Terrier, who bites and plays very aggressively with us. She bites, latches on, shakes her head and makes a type of growling noise. It's like she thinks we are a toy or something. The more we try to stop her the more she comes after us. I try holding still when she bites, but that doesn't stop her, plus the bigger she gets the more it hurts and it's impossible to ignore. we've had her since she was 9 weeks old and she started doing this a few days after we got her. We've tried saying ouch, she doesn't seem to care and usually gets worse. She attacks my hands as I try to put the leash on her. She sometimes just goes from nice and calm and loving to "Killer Attack mode" as I call it, instantly. She goes for the face a lot of times or anywhere else she can reach. I don't think she Is vicious, I hope its just play, but she seems to get mad when we try to stop her by picking her up or trying to restrain her at all. This is really starting to get dangerous, as she has bit several people in the face. I think one issue may be pent up energy, because she always seems to be very excited when she does this, though she sometimes is very calm when it starts.