As a Canadian speaking here.. We were down to -22 Celuis, which is only -8 fahrenhiet. (sounds so much better in fahrenhiet)
Anywhoo, yesterday/last night we were down that low. What we do, protect aganist drafts, number one, a heat light num two, and num three, a heated water bowl. So they don't have to drink ice cold water.. I'm sure it's still cold, but not frozen at least.
I think protecting against drafts a must, we also picked breeds that are cold hardy. Knowing that at some point, winter is a coming!!
At some point we will reach -40, it's expected, and we will repeat the same steps as above...
I would never do the chicken sweater thing, but I also would never do the dog sweater thing. I have a german sheperad, thier pretty tough in the cold. I would never have a little dog, that couldn't take the cold either. Cause I know our lifestyle, The most I would do for a dog, is put booties on them, and this wouldn't be to protect against that cold, but the salt and ice that will harm thier feet.
Good luck!! I love winter!! Oh also a must, shovel the way to the chicken coop.. Way easier to get to!!