Dog pooing in house

Question
Hello. About a month ago we got a new dog. He was 1 yr. old in April. He spent most of his first year being in a place where he and alot of other animals were abused very badly. When we brought him home, it was touch and go until he realized that he is safe now. As I said, he is 1, part Pomaranian and part Long hair Chihuaha and since we brought him home he has never peed or pooped in the house. He's always went outside. Until a few days ago, he started pooping on a throw rug during the night. We don't feed him after 6PM and always take him out at least 2 times after he last eats. The last time we take him out is around 9:30 or 10:00PM. When we get up, we find that he has pooped. We really want to stop this before it gets worse. Any advice will be greatly appreciated. Thank you.
Kathy W.

Answer
The throw rug might present a surface that approximates grass or some surface he associates with outdoors.  OR, the dog may have intestinal parasites which makes it almost impossible to control feces.  First, take a stool sample to the veterinarian.  If the stool sample comes back negative, repost and we'll address this as a behavioral problem (one which CAN be solved.)