My favorite winter coats are definitely these:
Designer Dog Clothes (Scroll down to the APACHE RIVER coats). These are not the most stylish but when it's *really* cold (and mine potty outside) these are awesome. They wrap around and cover their bellies completely so they are great for the snow. Seriously my favorite winter coats. Super functional. I bought them 2 winters ago and they are still in great shape so don't be scared by the price. They are very good quality.