I have recently posted on my 18 month old dog lunging at another dog at CGC class. Since then, the only other episodes were with another dog in the class constantly trying to lunge at my dog so needless to say, we survived CGC class and he passed without further aggression from him. Thank God. So, at our christmas party last week, my highly trained dog (kindergarden-Advanced and CGC) was out of line and I wanted to strangle him. Here's what happened. We frequently visit my mothers house and her boxer alot. I think he is territorial at her house too- so my aunt got a new puppy GSD- cute 8 month old very petite baby and brought her over. So, stupid me, decided that they should meet outside first so there is no issues indoor. I took him by the collar which was my first mistake because the leash was MIA. Brought him outside when he spotted the pup on a leash fifty feet away in the driveway. He immediatley started growling and barking so I put him in a sit and stay. Then once he settled down in that position, I thought he'd be fine with me just releasing him so they could do the doggy thing and sniff each other and since she seemed so laid back and nonaggressive, I thought he would be fine. Then disaster hit. He went charging over to her with his hackles up and barking like he was going to rip her to shreds (maybe it sounded worse than I thought) and what seemed like he crashed into her and of course this scared the crap out of the poor puppy and the puppy reacted and tried to hide behind her owner. She did growl I think or something because they exchanged snaping at each other. I ran and grabbed him, put him in a sit/stay and walked over to the puppy and patted her. I felt sooo bad. After the initial meet, they ended up loving each othe and played outside all day. He was amazingly patient with her puppy anctics and let her walk all over him and beat up on him. Anyone have any idea of what this behavior was and how I should have better handled it? I have a good idea but I would like to know what everyone thought of this behavior and do I have a vicious dog killer here and how do I train him not to crash into another dog? I felt pretty discouraged.