I used to live in the UP....still live in MI and have to deal with
below zero temps. I've found Dog booties are really the best
way to go if you can get your dog to wear them.....but if your
dog loses them a lot or won't wear them (like my current Jack
Russell - she refuses to move with them on) something that
works well is to clean their feet when they come in to get the
salt off and then put Bag Balm on their feet and put baby
socks on them for a few hours til it absorbs in.
otherwise they like to lick it all off ;-)
it's loaded with Lanolin and is very good at healing chapped,
cracked, bloody pads. If you use it regularly it will prevent the
severe chapping and cracking.

I also used baby socks, doubled and taped them on with
duct tape that worked as well as the fleece booties with the
velcro tabs and it's much less expensive when they lose them.

hope that helps
jude