She might need boots. The snow and ice gets into their paws. I only put a coat on my dog when it was EXTREMELY cold and/or snowing/raining, but he was a lab so in general not bothered by the cold. Smaller dogs will get colder, faster.

Cannot recommend Weatherbeeta jackets enough. So well made and long lasting! I ended up buying one at a local tack shop b/c pet stores didn't have coats big enough for my dog (lol) and I will never go back.