I go with either.
I lived in the UP (MI). We never blanketed our horses (except I remember tying on a fleece blanket with baleing twine when it was severely cold for a week or so (Mom wasn't too happy about that one). Other than that they grew really thick coats.
Then I lived in WA. I thought with the mild weather on the west coast no prob. Wrong, the winters aren't too cold but very wet. Guess what, constant rain also presses down guard hairs making for very shivery miserable horses. So I bought a simple rain sheet and my girl was great.
I am now in KY. I tried going the no blanket route last year but the weather is too crazy. It can go from dry and 60's to wet and 40's in a single day. So all my girls have a blanket. My pregnant girls wear a midweight and my other girls wear a simple waterproof sheet. It is difficult in the fall and spring as I have to sometimes take them all off in the am feeding and put them back on at pm feeding. That's simply part of the joy of owning horses.
I think the biggest difference is not the cold but the wet. If you live in a dry, cold area, horses will be fine but I'd recommend a blanket in a wet, cold area. Are they going to die without it... probably not if they are healthy and well fed... but for me it's the knowledge that I won't have muddy, shivering, and miserable looking horses when I go to feed that made the decision.
Last edited by Crossover; 10-20-2011 at 08:44 PM.