My mare is on a diet right now and the vet restricted treats to sugar-free only. The ones I've found that she really likes are peppermints & also butterscotch (that's a new one she LOVES)
They were both at the local supermarket...here's a good website if you want to stock up: Sugar Free Candy, Sugar Free Lollipops, Diabetic Candy
They have a hard candy mix that I'll bet the pony will LOVE! I want to get the IBC root beer hard candy and see what my pony thinks about it, I love letting her try out new treats!