After a good training, I give them sugar cubes, because usually I give them treats while they have the bit in their mouth and sugar dissolves in their mouth!
I have some treats that you buy in horse stores to give them when I put them in the stable!
Hope it helps
There are a great variety of healthy treats to give. I like giving apples and carrots. They love licorice as well, but I tend to limit how much I give because of the sugar content. I also sometimes give dried beet root which has some good health benefits.