(1) send a letter to the company explaining your concerns. in theory, if they get dozens of more letters from people that support dogs than from people that want to get rid of them, they should reverse the ban. and, send the letters to all of the companies, not just the ones in canada.
(2) while you're waiting, boycott companies that ban dogs.
but, you have to realize that this struggle exists before you can react to it. you don't realize it, and that's at the crux of the problem.