Sounds like your weather is a lot like Indiana's too (as of late
anyway!). I know my Cushing's girl has been doing ok, with the
exception of a couple abscesses and her sole is still healing on her
toes from them. That makes her sore walking unless I keep her in her
Sabre Sneakers. So, she's staying in her sneakers. I also have been
putting her canvas/felt blanket on in the evenings. It's dipped into
teh 30's lately here and it seems she is not stiff in the mornings if I
have her blanketed.
I'm checking her (and her IR daughter) crests, and it does seem like
they have a bit more of one (only in a small part though) and I'm not
sure if that's just from what little they can snarf through the tiny
holes in the muzzles. I've sectioned off a small part of my front
pasture that has very little stubble in it, but it is the DRIEST lot
right now. Both are booted and the not-so-dry-dry lot just isn't
productive to healing abscessed feet in boots.
I'm glad you aren't so rattled today! I've never been one to baby my
horses (blankets, no way!) but now, I do and it makes the ones who need
it happy and keeps them healthier. I don't need her gaining weight, and
using her calories to keep warm will maybe make her too thin... so it
makes sense to put a blanket on her!
Maybe adding a sheet/blanket at the cold (under 40 degrees is my limit)
nights will help her not 'crash' as you've heard others in your area
doing on controlled diets.
I'd say as long as she gets to choose to go in and out, it shouldn't
hurt, but see what the others advise (I'm not what I would say and
'expert', I am suffering with this as well!!!)