
When I introduced an adult dog to my two Staffies, one of whom is very dog aggressive, I had the luxury of a couple of weeks introduction before the dog moved in .
I took them all out for walks with the help of a friend, I intially had my friend walk the new dog a few yards in front of mine, so they could observe the safe end and have a good sniff at the scent he was leaving behind, they got as much info about him as possible without feeling threatened. I then turned it about and had them walk in front, it only took a few days before the Staffies were ok, I then progressed to car journeys and house visits.
Once the new dog came to stay for good, it was pretty much plain sailing .