As has already been pointed out the turnbuckle doors are a problem. Stuffing a small dog in front is one solution but may not fit all needs (and you need 4 dogs).
Any other ideas on what could be placed out side the door that might insulate and cut down on air infiltration? I thought of a small down pillow but it is likely to get wet out there.
I plan to put a flap of reflectix insulation over them this fall.