We rescued a year old boxer mix a year ago so he's 2 now. We instatalled a doggie door so that he can go out whenever he wants, it is fenced in and secure. He uses it all the time when we are home to relieve himself. However, when we are not home he has accidents all over the house. He is impossible to contain in any area of the house, as he opens doors and can jump over or break out of any area where we have tried to contain him. He is too big to stay in the largest crate for any period of time. We have instilled all the alpha techniques and generally he is a very good dog. Since he knows how to use the doggie door and knows what it is for I believe this is just spiteful behavior.
Please let me know if you have any suggestions.