I have a 6month old female Lab and a 9 yr old Lab. When my puppy plays with him, she behaves very aggressively. She jumps, bites although not hard enough to draw blood, and all the while her hair on her back is standing up. My neighbors 1 yr. old Shepherd came over to play with her and she wanted to go home within 5 mins. because of this behavior. She is also growling the whole time although it appears shes trying to play, just too hard. I don't understand why she behaves this way, nor how to stop it. Shes really wearing out my older dog, when I was hoping she would keep him company since my other Lab has passed. Can you help me with this?