My year old Border Collie mix has been completely houstrained for more than seven months. We recently got a new German Shepherd puppy. Last night and tonight, my older dog pooped right in my dining room. WHY?

There is no doubt in my mind it was a deliberate showing of who is who. It may have been meant for you or the puppy. The key to most behavior problems is approaching things using the dog's natural instincts. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at Raising Your Dog with the Monks of New Skete For more on being top dog, see Establishing and Keeping Alpha Position

See the sticky for help with the puppy, https://www.askmehelpdesk.com/dogs/i...tml#post251802

While it is not unusual for a dog to have an occasional 'accident' for the first year or so after they are housetrained, I have to agree with labman that this seems to be a behavioral thing. The Border Collie could be saying to you "I don't like you bringing this new puppy into the home!" and to the puppy "This is MY house, and don't you forget it!".

For immediate help, I think you should crate both dogs at night. This will help the Border Collie feel a little more secure, will control the "pooping" issue and will let both dogs know that YOU are in charge. I personally think it will wear off quickly as the dogs establish their pecking order in the home.

Good luck!

Didi