I don't know about Canada, but the US is the only place where "Greyhound therapy" is a thing, and no it's not homeless playing with dogs. Basically, cities just ship their homeless/mentally-ill to another city via Greyhound bus lines. Some cities get the short-end of the stick more than others.
I discovered it first hand taking a bus from Philadelphia to Pittsburgh.
https://en.wikipedia.org/wiki/Greyhound_therapy