I have used this "Plexidoor" from petdoors.com for many years and it has held up fantastic. But it is not cheap and the XL may be too small for your dog
http://www.petdoors.com/plexidor_wall_unit.htm
At our last house I build this dog house, on the outside was a cheap flap door, then on the inside was the plexidoor into our laundry room.
By far the best solution yet. It was never drafty and the extra room helped keep dirt outside.
Pat