Bad Dog

Question
I have a 5 month old APBT. He is wonderful, or has been until this past week. He was completely house broke by two months, has never chewed anything except his bone, never got in the garbage or on the table, etc. He is a wonderful boy and the only four legged member of our family. I social lize him constantly and he goes every where with us. Last Thursday my sister broke her leg and asked me to keep her dog because she was unable to care for it. I hesitated and didn't want to because her dog sucks. due to guilt I accepted and brought the mutt home. the first couple days were fine and the dogs played well together, but my sisters dog has no manners and is not very well trained. Since Thursday my dog has now decided to use the house as his toilet (no walking habits have changed, I walk him by himself on our normal routine and take her dog out after), he has torn up the garbage, chewed up his bed and is not listening to basic commands. Prior to this I would call him he would come and sit and wait for the next order, he would not move until I gave him his release command, now when I call him he goes the other direction. I know it has something to do with this other dog, but what can I do?

Answer
Start back at square one with him, Jeanne. Since he behaved well before, it will not take him long to get back to that level of obedience. Also, if you have time, work with your sister's dog as well, so that IT can learn some manners and stop rubbing off all of its bad habits on your puppy. Don't allow the two of them to be together all the time. Separate them for short periods of time every day. Since your sister's dog is not a well balanced dog, you might be better off keeping the two completely separated, except for daily walks, providing you can walk them both without having to fight either one of them to keep them walking nicely beside you on a loose lead.