is not a woolen kennel coat sufficient ,in colder nights,.a good deep bed of straw/wax paper and a kennel coat ? in the winters when snow was heavy and temps .hit minus i had heat lamps on all night ,then turned em off by day and put kennel coats on till night time ,back on with the lamps..once the dogs held their weight and never lost condition i was satisfied they were sound, good quality warm food plays a large roll in the ,situation too i think