Just got an American Pit Bull Terrier (Lola Faye) as a companion for my lab/shepherd mix (Bear).
He's 7 or 8, she's about 5. He's a Hurricane Katrina rescue, she's a mystery transferred to my local humane society from another humane society in a rural part of the state. That's all we know about her past.
We are one our first full day in the home together. They were playing very well last night, taking turns humping each other after play-bowing, but this morning Bear is not interested in the humpy game. She's quite tenatious about playing but backs off if I spritz her with water. If I'm sitting still, they are both sacked out. If I get up, she explores whatever room I'm in briefly before returning to my dog and mounting him. Normally I'd let them outside to work it out (supervised, of course) but there's a foot of snow on the ground and it's about 30 degrees. Neither will stay out long enough to tussle! Meanwhile, I live in a tiny house.
Good things about the dogs: when I fed them breakfast, she first ran to Bear's dish and started eating from it at the same time he was eating from it. He didn't growl and she didn't care when I picked her up and placed her in front of her dish. Also, she apparently doesn't know stay, so we've been working on some basic commands in short spurts with treats. Both dogs are digging on this. We took them on a walk last night and they walked very well together.
However, I've been reading up on the breed and have to say, I'm a little worried. I don't have the pit breed bias, but I do have a thing about terriers. She seems pretty mellow for a terrier, but the tenacity of her humping and the terrier's known hyperactivity/voracious mind/easily bored temperment is worrisome. Especially in light of the stories I'm reading online about not leaving APBT's unsupervised with other pets under any circumstances. I'm worried I've gotten the Eddy Haskell of breeds - sweet to your face, a jerk when away from the adults!
I have several questions for anyone who has experience with the breed, especially with the breed interacting with other pets in the house. (Oh yeah, I also have two cats who she's shown interest in but has not chased at all.)
1) Do I have any hope that this humping/dominance behavior might some day subside?
2) Do I have to crate her when I'm gone to work? I'm only working 20 hours a week, and my partner is home many of the hours I'm gone, so at most she'll be unsupervised with the other pets perhaps 8 hours during the week. This may change in January when I may have the opportunity to move into a full-time position at work. That's one of the reasons I got my dog a companion; I'd hate to leave him with a companion who's locked away or who is constantly worrying him.
3) I would not have picked a terrier. She is my partner's pick. (He wanted a Jack Russell but I knew I couldn't deal with that level of energy!) The training falls to me both because of my work schedule and because I have a lot more experience with dogs. Tell me love stories of terriers, DUers, because they are few and far on the webs!
4) What kind of toys might you recommend for Lola Faye? My dog loves buffalo bones but is pretty bone aggressive. He's been very good at sharing stuffed toys and tuggies with other dogs. I was thinking I might get her a Kong and fill it with peanut butter so he can still have his bones. He won't touch any latex toy. Any ideas here?
5) Her coat seems short and thin - do I need to get her a dog sweater for walks?
I'm sure more questions will arise as this goes on. It's been less than 24 hours since we met her and it's all still got to be a little weird to her (and us all). I may be over-worrying - it's been known to happen. But I thought I'd post anyway to see what wisdom my fellow DUers will have to impart.
Thanks! 
= new reply since forum marked as read
She is the sweetest dog on the planet, smart as a whip and very cuddly to me, my partner, and our other dog. (The humping stopped in less than 24 hours after a few short sprays with the water bottle.) However, she absolutely cannot be trusted around the cats. She's gone after them both and whenever they enter the room it's like watching a Hitchcock film: when will the shower scene occur? Her normally laid back demeanor becomes rigid, her whole body tightens, her muscles twitch, she's even drooled a few times. Calling her name and using the spray bottle has no effect whatsoever. She is much more interested in the cats than the squirrels in our yard. I've had many homes with cats and dogs and know the difference between a dog's curiosity towards a cat and the dog kicking into predatory mode. All I can say is, I'm glad our local humane society is a no-kill facility. I'm sure this dog will make a wonderful pet in a cat-free home. Unfortunately, that's not the home I live in. 