My 4 silkies who are 5 months old were so cold this morning when I went out to get them. They had frozen condensation?? on their head mostly. I didn't want it to progress so I brought them into the garage and put them in a large box. They are loving it. How long should I keep them in? I am also worried about now they are so warm and I don't want to shock them when I put them out. Last night was -28 F and today it's about -10 F. How should I go about doing this?