We have our little 4-month-old Max who is a super little dog. He stays outside all the time except for 'visits' when we bring him inside the house to play for a short time or take him for a ride in the car. Well, he never complains at all outside - no whining, no crying, no barking unless something or someone strang is seen. But, tonight it's going down to 18 degrees F here in Oklahoma and I'm a little concerned about him. He has a dog house with a flap over the door so it's not airtight, but it's close. There is no heat inside it however. I'm wondering if just the little guy's body heat is enough to keep him warm. Oh, he is half Anatolian or Saint Bernard and half Great Pyrenees. He weighs about 35 lbs. What do you think? Will he be ok?