I love all dogs. When I lived in Florida there were quite a lot of Pit bulls. I was afraid at first, but they're gorgeous and not at all like their reputation!
People can be scared of them because they were originially fighting dogs
That's right. Some people still train them for that cruel sport. But if they're properly trained they make great family pets.
They are also used as catch dogs in the US, and as family pets
What's a catch dog? I haven't heard that term before.
They are trained dogs for catching large animals, such as when hunting or working livestock
Oh, I see - sort of like a herding dog I guess. What are their origins?
Herding dogs have been around a long time.  Collies are considered good herding dogs
I like collies. Where I come from pretty much every farm has a collie for herding.
Collies come from Scotland and England mostly