I don’t know about Canada but down here in the hellscape(I mean America), stuttering is a condition protected under the Americans with Disabilities act. If we protect candidates and employees then I’d certainly assume Canada would also have protections. Actually I just reviewed google and you have the ACA up there. If you are qualified and capable of the requirements within the job, they can’t deny you the position just because you stutter. I would be upfront about your condition even prior to the interview. Short answer is that every company can and must hire a person who stutters if they are an otherwise fit person for the job. If you are finding you are being repeatedly denied positions and you genuinely are qualified for these positions, I’d look into how you report that with the human rights commission.