I use vanilla yogurt, buy it in the large tubs. Yes, it would work with dry food, makes them want to eat it more. Winter is a hard time of the year, almost all my dogs like poop sicles
Or go to the health food store and buy a probiotic blend. I use one called PB 8, it's in capsule form, so I open the capsule and sprinkle it on. I've had really great luck with this and pups who will turn around and eat their own poop. What probiotics do is help you to digest your food better, so you are using your food better and your stomach doesn't get upset during digestion. I used to have a lot of stomach issues, but have been on probiotics for years now and can finally eat without pain all of the time. I was one of those always on antibiotics kids, so my gut was probably totally stripped of good bacteria that aids in digestion.
I've also heard of people buying the HOTTEST hot sauce you can find, pouring it on and then letting the dog eat it, they vomit quite a bit, but may be reluctant to eat poop again. Don't let him see you do it though.
Or adding ground up pineapple to the food.
My boston terrier has big time gut issues and I've been unable to curb his poop desires. But am working with a holistic vet now on getting him well again, so maybe....