My good friend has a Boston that she runs in agility. And Jitterbug(the Boston) comes from health tested and titled lines. She is much more of a bulldog mentality than a little dog. She is extremely driven and a wonderful dog, she is dog aggressive but from my understanding that is not typical of the breed. Her parents were titled to UD titles in AKC. I believe the kennel name is WyNot. I need to double check that. Jitter is tiny, less than 10 pounds. You can see pics of her on my Facebook. Watching her in agility is amazing, she is an amazing agility dog and trains with Barb Davis regularly. She has never had a problem with overheating and it gets warm here.