I carry a backpack with me when I leave for the day. My dog who is housebroken and will not go in the house unless I don't let him out, pissed on my backpack the other day. He managed not to get any on the carpet below. So I washed the thing. like 5 days later he pissed on it again, once again managing not to get a drop on the carpet. What is going on? Is he doing this because he is upset that I have to leave him to go to work?