Normally the treats for our horses are carrots or apples, every now and then an actual horse cookie.
The most unusual treat for my mare is a kosher dill pickle. She loves them.
Once after a trail ride I gave her a pickle and my friends old guy was watching as I usually offered him a sweet treat, too. I handed him a part of a pickle, he took it and then dropped it in horror. He stood there a minute working his mouth (still tasting the pickle) and then WOW! Light bulb went off, that ain't half bad. He reached down and picked his pickle off the ground, munched it down and turned to me to ask "do you have any more?"
Just DO it and be happy that you can!