Wolfdogs dig holes.
This is a natural behavior that most if not all wolfdogs will exhibit. To try and stop the digging is not only futile, but ultimately a cruel attempt to stifle a perfectly natural behavior.
Digging at the fence-line, however, should be corrected. As I've explained in my previous pages, wolfdogs are wonderful at understanding human speech. Explain to your wolfdog that digging at the fence-line is not okay.
If he tries to dig in the center of the yard, ignore him. This way, he understands that certain areas in the yard are okay to dig in, but others are not.
You will occasionally get the 'gross' wolfdog who won't mind digging in his own poop. One with such an ambitious wolfdog may need to resort to lining the fence line with concrete at least 4 feet below ground level, or burying the fencing at least 4 feet below ground level.
But I believe you should always leave a small spot in the center of the yard or enclosure so your wolfdog can still relieve the natural behavior of digging.