Certain treats like that are good for them. My trainer and her father have been feeding their horses all kinds of stuff for over 80 yrs and they were all healthy. The vet said that as long as you don't give them too much of anything it wont hurt them.
Every christmas we would make our horses carrot cake and every one of them would get a slice! They enjoyed it very much.
But I too give my horse beer everyonce in a while bc the vet said it's good for their digestive tract. But I also give him soda, and animal cookies, watermelon, cookies, pizza, you name it and he'll eat it. Except for sugar cubes, none of my horses will eat them. But he's still healthy and i've never had ne type of health issue bc of the stuff i've given my horses!
"The horse you get off is not the same as the horse you got on; it is your job as a rider to ensure that as often as possible the change is for the better."