Housebroken/bell/crate trained dog having accidents.

Question
Our 7 year old Maltese (Molly)has been having accidents in the house several times a week.  She has been sneaking off to do it. She was our only pet until we took in a stray dog 9 months ago.  She and the new dog do snuggle and sleep together so I think she is over marking her territory or any jealousy.  Usually I just clean up the mess as quickly as possible (sometimes she watches me).  If I catch her in the act I say no and immediately take her outside.  She usually sneaks off when we make start making dinner or sit down at the computer.  She is bell and crate trained.  We also shampoo the carpets frequently.  How do I retrain her to be housebroken again. She is absolutely loved and adrored consistently and constantly and is such a good dog (and healthy too!) that I am baffled about this.

Answer
Hi, Michelle.  What you are experiencing is not that rare.  Dogs often have regression in their house-training when there is a change in the household, such as new baby, moving, adding a pet.  The solution is just to go back to housetraining 101 - i.e. she gets no freedom in the house, you praise for going outside, you do NOT scold for mistakes (that's what makes her hide - she's doesn't want to pee in front of you since she knows you will get upset, but she doesn't realize that over-marking the pup's scent is not OK).  Hopefully, once she realizes that you want her to continue outside elimination, and not do anything about the funny puppy smell in the house, things will get back to normal.  Be sure to use an enzymatic cleaner when you clean up, such as Petastic, so that she won't go back and think it's ok to mark over old puddles.