It very well could. Or the current dog could learn to accept it in time. Again, to use my own dogs to demonstrate, Sawyer wouldn't let Aubrey get within 3 feet of me at first, because he sees me as "his". He knows that I run the show and all, but he didn't want to share my attentions. But eventually, he calmed down some. He still has to be right on top of me whenever possible, especially if Aubrey's getting attention, but he's adjusted.
I think given time and the right introduction/continuation, it may work. Getting an older (2-3) year old spayed female might help as well, instead of looking for another male. Mixed pairs usually get along better than same-sex pairings.
I think given time and the right introduction/continuation, it may work. Getting an older (2-3) year old spayed female might help as well, instead of looking for another male. Mixed pairs usually get along better than same-sex pairings.