How to stop my dog from pooping inside?

I have a 5 1/2 year old Shih-Tzu. He was completely potty trained and doing great up to the point of him being attacked by a coyote at 6 months old. Ever since then it's been a struggle. He doesn't usually pee inside the house and if he does you know that it was because he just couldn't hold it or if it's to "mark his territory," even though he's been fixed since 6 months. He has on occasion pooped inside. It hasn't been an issue until recently. In the past year or so he poops inside at least 3-4 times a week. It's getting ridiculous. We constantly let him outside to potty and every time he starts sniffing or wants to go out we let him. He only poops inside when no one is home. Our other dog (2 year old mutt) has only pooped inside twice - once when it was raining outside (she hates rain) and once after eating another dogs dog food. We feed them both at the same time and they both go out at the same time. She doesn't have a problem but he does. Every time he does poop outside we REALLY praise him and give him treats. When he does poop inside, he knows he's done something wrong. I don't understand why he's constantly doing this when he knows he's doing something bad and when he knows he should go outside..Please help!!

Some adolescent and adult dogs (over six months of age) urinate or defecate inside the house. If your dog soils indoors or at inappropriate times, it's important to visit his veterinarian to rule out medical causes before doing anything else.

I would consult your vet. He could be suffering incontinence due to a medical issue. It's important to have a running dialogue with your vet about any health or behavioral problems that are going on, because things that may seem insignificant to you could be the sign of a larger problem. I had to have my cat put to sleep recently because I didn't realize how serious his issue was until it was too late. I usually call my vet about things, and I regret not taking my cat's strange behavior more seriously.

Dogs do not have any idea about the nutritional content of the food that they eat so do not be surprised if you caught them eating poop.Read more information you got here: http://www.knowswhy.com/why-do-dogs-eat-poop/