Just a thought, but what about that bitter orange stuff? My GSD Abby pulled a nail once and had to have it cut out. They put a bandage on it and sprayed bitter orange on it so she wouldn't try to chew it off. Worked like a charm. Maybe you can get some, I know they sell it at petsmart here, or even check with your vet, and spray it on the poop as soon as they go. It's worth a shot, or anything you can spray that won't harm them but tastes bad, like a lot of lemon juice or something???
Best of luck,
MD
Best of luck,
MD