Keegan's surgery is over. So far, so good. He's just gotten home and is sleeping. I've had to move the others' kennels so he has his quiet place (he was already growling when he got here)...Fingers crossed that, over time, his aggression issues will fade with his hormones.
Sidenote: Keegan's girlfriend Summerlin (not even kidding--these two have been love-struck with each other since puppyhood) was spayed today at the same location. We had, once, wistfully thought about what adorable pups these two would have had together, but we're not BYB, Keegan is an off-standard Yorkie, and we don't wish to contribute to pet overpopulation (hence the rescue pup, instead). So, we're looking forward to them being able to visit each other more safely now.