How do I get my friends large breed, dominant dog to get along with my boxer?
If you KNOW that your dog doesn’t get along well with other dominant dogs then you need to hire a behaviorist to help with this introduction. There are certain things that you can do to ease the transaction but we cannot tell you those over the internet – a behaviorist needs to show you hands on. Until you can hire a behaviorist then do NOT make any attempts at introduction. You do not know how to read body languages and/or prevent/break up fights should they occur. You do not know if their interactions are purely dominance scuffles or plain aggression. Any time you bring two dominant dogs together you can almost guarantee a fight to break out once, if not several times. Usually a pair of dogs will work things out themselves if it is true dominance, but if you have two stubborn dogs then things can end badly.
