The episode gives a bit of history behind the ghost dogs; they used to be robbers hiding from the law, but they were attacked by dogs and killed. The robbers now haunt the woods looking for humans to switch bodies with them.
In the episode, Cooper and Margaret are turned back to normal, but Cooper's older brother Mickey is transformed into a chipmunk as a punishment for harassing and bullying him.
In the episode, the Changing Room is called the Changing Tree. It's the former in the book.