You'll have trouble practicing in Ontario as a DO or an MD. They simply have too many physicians there.
DO's can be employed in Canadian hospitals. However, you should remember that DO's are considered as Foreign Medical Graduates and they must take the MCC Evaluating Exams before they can take the LMCC 1 & 2. I'm sure that you won't have to worry about passing the EE, but you should know that it is an extra hurdle.