I have the WORST behaved dogs on the planet. The puppy has torn up just about everything. But they don't dig. Riley (the puppy) brings in about 100 pounds of dirt into the house every day either by way of paws or with the dozens of rocks and sticks he brings in. My dog sitter actually referred to the laundry room (where they stay with a doggie door to the outside while I'm gone) as "the sandbox". I could FedEx you MY dirt for YOUR holes
What's really weird is when I hear a strange screeching noise - he is actually CHEWING on the glass door. It's pretty funny to watch from the other side ;)