I think I can join Mike in the expert category. I live in Northern Manitoba in Canada. Our city, Thompson, is about 600 miles to the US boarder. We get LOTS of snow. We got Bailey in January (stupid time to get a dog in our climate)
and I have to say, I tried her once in the snow and that was it! We had by this time about 3 feet of snow so we thought because she weighted a little over a pound, the snow would support her. Wrong. She sunk like a lead balloon! So needless to say, never again. From that point on, we have used puppy pads. The other worry we have is the cold. It can get down to 50 below zero ( or -50 celsius for my Canadian counterparts and UK Poster). On the milder days, even if she is going for a cart ride, we dress her in booties and sweaters. I know a great place to get booties that fit, so if you move, contact me.