It seems like male/female pairs tend to do better than male/male or female/female pairs. I guess the reason for that is because packs have female and male alphas, not just one sole alpha. Since he's more dominant, I think maybe that would be the best choice.

I had a really hard time getting Kaedyn to tolerate being near Kai. He warmed up eventually. I think fostering might be good. Sometimes it takes a bit for the dog to get comfortable and really show their true self. Kaedyn acted like an angel at the pound. Then we got home and he was a nightmare.

I guess breed can matter but.. you never really know how a dog of that breed will get along with Max. I think in this case, breed should be taken into consideration (if at all) after you've found a dog that's compatible with Max.

I think your best bet is just going to the shelters regularly and maybe actively fostering until you find the right dog.