It takes on a whole other meaning for horses, and a lot more work. They need to be outside moving around, and will be fine in subzero Temps as long as there is no wind, and they have lots of hay and water.
However, with the windchill as cold as it is supposed to be, mine will be inside, with lots if hay and water. This also means lots more poop inside, and that they will be like a coiled spring when they get to go back out, ready for a good buck.