Do you mean to say you can't own Pit Bull's or Rottweiler's AT ALL in Canada, or just in your city/province?
If they're banned in Canada, why? Couldn't you just shoot them with a gun, which isn't banned?

If it's just in your locale, I'm betting after a rash of attacks (numbering in the tens of tens) by dogs of piss-poor owners, local officials felt the need for ACTION, and quick-like!
I've heard it was a common occurence with landlords all over for those types of dogs, but hey, they own the friggen buidling. You don't like it, move or buy your own place, or wait to buy the dog until you CAN own it without problems.