rspca pets are definately behaviour tested, and will often have a note in their profile, like not good with other animals, children etc, if a problem has been detected.

all of our dogs bar 1 since i was a kid have been from the rspca, it's a great thing to do, most puppies in pet shops will get sold, whilst a lot of rspca pets will sit there for months.

our puppy max, who is now 1, was found as a baby, having been abused etc, we got him at around 12 weeks, he is the nicest dog, chews everything, but is brilliant with the kids so we forgive him. the only thing we've noticed with him is that he is submissive around other dogs and people he doesn't know, which isn't entirely a bad thing.

go the rspca, you'll feel good, get a great pet and save a life - but check those notes first!