No domestic dog breed in North America is 'vicious'. The breeds that have lives this long have survived because their good tempers. Some dogs were bred to hunt, to fight, and to guard, but they were not bred to be vicious.
Just like with a child, if you raise them with violence (Hitting them, abusing them, and neglecting them) they will most likely grow up to reflect that upbringing, not all will, but most. The same is true with dogs.
I live in Ontario, and it is the only province in Canada where pitbulls are banned from what I know. The one and only reason they are banned, is because of the media. Over the past few decade the news media has tried to sell fear, and it works. People don't want to watch the news and hear about a pitbull who is a well mannered, nice dog, they want to hear about the pitbull who bit the the 10 year old kid. To be able to sell fear, you have to focus on one target (pitbulls, terrorists, the economy). If you say "all dogs are vicious" people will know its a lie, but if you pick a certain breed which has a bad reputation, people will believe you.
In my opinion, the reason pitbulls are known to be vicious is because people buy them for self defense, and poorly train them. They don't buy the dogs as a companion, but as a weapon. Once pitbulls are banned, people switch to the next "vicious dog" like rottweilers . The only way you can avoid bad owners using dogs as weapons, is to ban every breed of dogs, with the exception of chihuahuas.
