He has a very thick winter coat. He is like a sheep, LOL! He does not have a run in or any trees in his pasture. I checked him before I left (it was 25F when I got in my car) and he was not shivering or showing any signs of distress. I checked his belly, between his legs, etc. and he was actually pretty toasty!
My boyfriend's horses insist on standing out in the elements. They bought a lovely barn and run in for the horses and it really ticked my boyfriend off when the horses refused to go inside. Horses are just horses it seems!