Which deterrents have you tried? Is he eating his stool only when you're not home, or will he do it right in front of you?
Thanks for replying Gwen. I would try 2 things for this.
First, the only deterrent that I have seen work with good success is For-Bid. If not available at your local pet supply stores or veterinarian, it can be purchased online. They sell tons of these deterents, and I have even heard people use hamburger meat tenderizing powder in the food to make the taste foul, but only about 50% of people claim any of these work with consistency. Try the ForBid for starters. Here's what it looks like (at bottom of page):
http://www.sitstay.com/store/health/healtha.shtml#HBFR
Second, it's possible this habit is starting out of boredom when you're not around. I've found that having a tasty long lasting snack/bone only when you are leaving him works wonders at stopping bad habits while away. It'll taste much better to go for a bone with frozen peanut butter inside it, or even pre-made bones with flavored foods built in, some made even for the strongest jaws, and others tiny and made for little breeds. I'm sure you can find one appropriate for your Scottie and his chewing bilities. They even have veggie flavored for those on natural diets and such. Kong toys with treats stuffed in and "puzzle" type toys with something yummy also get their attention. Distracting him for the first few weeks of this new routine will get him in the habit of concentrating on something else while you're gone, and with something long-lasting, he'll be going to the box to do his business, but rushing back out to get to his tasty toy. between that and the ForBid, I think you'll see good success!
Hope the problem is fixed soon! Best of luck,
Christine
Certified Veterinary Technician
Licensed veterinary technician (B.S. Mercy College), 10 yrs in animal medicine and training