Gidday from Canada
Yup, as the name indicates, I'm from Canada and have a lifetime of experiencing cold winters. "Jinx", being a typical boxer, never grows much of a winter coat (OK, none), so I got her a thin doggie blanket (not unlike a horse blanket) for when the temp starts to drop to below the freezing mark, and a nylon shelled, thinsulate-lined coat for the really cold stuff that usually arrives after Christmas. She generally does just fine without any coat until we hit about 0 to -5C (I guess that's about 23F). Below -5C (23F) she wears the thinner coat which is also a windbreaker, and once the thermostat drops below -20C (-4F) she wears the "parka". She does very well when bundled up and sometimes she even wears boots (-35C and below). No, I'm not exaggerating, we generally see at least a couple of weeks in the winter of -35 to -40. (Just to let you know, -40C = -40F.) "Jinx" loves her coats and plays/jumps/bounces/wiggles, etc. with no problems, even in the boots. Maybe I'll take a photo of her decked out in her winter duds and post it on this site!
Jane