Looking for some advice. Kaiser is my 2 year old GSD, not fixed. My fiancé also have a 6 month old golden retriever in the home. These two get along great and play all day. I have a big fenced in back yard with lots of room to run. Recently, a friend of mine rescued a Pitbull mix. She works long hours and asked if she could drop him off while she is at work sometimes. He's very friendly with people and other dogs, and was recently fixed. So yesterday was day 1, and Ogie (Pitbull) and Cooper (golden) get along great. They play play play. But my GSD is territorial, and is very on edge. They have had multiple interactions sniffing each other out, but it usually escalates to a mini fight. I can tell both dogs are dominant, and my GSD is feeling like his territory is being threatened. I've tried to "introduce" them by telling Kaiser it's okay, etc but no luck yet. Today is day 2, and same situation. I want to take them both down to the park (neutral territory) and see if they get along better. Wondering if anyone on here has been in a similar situation, and had successful positive interactions between the dogs. Thanks!