Berner cold weather tolerance

[Thomas Torsney-Weir]

Ok, my 9 month old berner loves being outside (especially in the snow) and I'd love to take him camping on the Appalachian trail. I definitely don't want to wake up next to a frozen puppy and it can get pretty cold at night, so how cold can it be for these guys to be comfortable (and not freeze to death)? He does curl up in the snow and go to sleep on the other hand snow is a great insulator...