Your dogs digging might be a sign of not being stimulated enough. Either find him/her a activity to that will keep it busy or train it. Training can be done by first bringing it outside. Once it...
In the book "Holes" By Louis Sacher, they are digging holes at Camp Green Lake, the Juvinile Correction camp, because the camp warden believes it helps them gain character but later in the story you...
With wild mice it's hard to tell because they usually start digging under a bush and you can't see it, if your talking about a pet mouse, I guess it would be dirty, but I'm not sure how a mouse could...