We don't get temps nearly that cold here in Oklahoma so I can't imagine what -50 would even feel like.

This is just my opinion, but I think that's much to cold to have him out in for a walk. I don't let mine out for more than a couple of minutes when the temps get down in to the teens. Their little bodies just don't have enough insulation, even if you do have them all layered up.
I know he'll need exercise but I'd recommend you find a way to keep him indoors. Can you play fetch or chase or something inside to keep him active?
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