As does YVR but not YYZ if I am not mistaken.
I would suggest checking the floor map of the Ottawa International Airport to clarify.
I don't believe that Ottawa has a lot of US flights at all ties of the day. That means that the US pre-clearance facility may not be open at all times. This could cause some problems for you.
The other risk is you could get denied boarding by a check in agent that doesn't feel you have all the appropriate paperwork. However, that's only a risk you can assess and determine whether you feel comfortable with...