Mini schauzer is obsessed with a drainage pipe...

Question
Our 7 diversions. old schnauzer is obsessed with a drainage pipe in our yard.  Further investigating has uncovered a family of mice dwelling inside.  The dog is quite intelligent and will walk the retaining wall to check both ends of the pipe nonstop for an hour if allowed.  She is now so fixated that the typical favorite diversions of toys, treats, or a walk will not deter her.  This housebroken dog "forgets" to go to the bathroom outside.  When she is inside, she stares through the window at the pipe.

Previous springs have brought a fixation with a rabbit hutch, squirrel, or bird but never anything like this.  

An obvious solution would be to get rid of the mice, but I fear using poison having already lost a dog that way.  Further, I suspect she would turn her obsession to another item.  

Any and all suggestions are appreciated.  We miss our loving pet.

Answer
Hi, Lisa.

Does she like to play tug-of-war and fetch? Other than obsessing about the mice, what are her favorite activities? Does she get a chance to engage in rough-and-tumble play with other dogs on a regular basis? How much hard vigorous playful activity does she get every day?

LCK