Hi T.,
We had the same problem w/ our two dogs...it's such a pain!
Anyway, here's all the advice I got:
1. Put shaving cream in the hole they dug and on their nose and paws
2. Burry their feces where the dig (I thought this was rather gross; but you can try it)
3. Catch them digging and shake a tin can full of rocks to startle them. They supposedly learn not to dig because they don't like the sound of the can shaking.
4. Create a space where they can dig and burry bones there. Praise them for digging in the right spot. Every time they dig in the wrong spot, take them to where they are supposed to dig.
We tried all but #2; but couldn't do it consistently enough to make a difference. Eventually, they both stopped digging on their own.
Good luck!
G.