I've used both the powdered form and also some pills. In both cases, I could just add it to the horse's grain and they ate it fine. I usually keep some on hand in case my one hivey horse has an outbreak, with instructions from the vet on dosage.
The powder used to be call Azium. Anyone remember? Then they stopped making Azium and you can only get it from a compounding pharmacy but most vets have some on hand. I've fed it to multiple horses over the years and never had problems with the taste.