Horse owners have frequently shared their concerns about horses’ choking eating pellets, but very few have had a horse choke. Assuming there are no structural problems/lesions with the esophagus and oral cavity and a horse exhibits typical eating behavior, a horse is not prone to choking on pellets any more than some other feed form. However, a horse that bolts his feed, senses competition from other horses (even those in the next stall/pen), is generally nervous, or an aggressive eater may need to be managed differently during feeding. That’s not a problem with the feed but an issue with nutritional management of the horse.
Nutritional management with feed bolters, etc. include a feed container that is wide and shallow, feed in smaller amounts more frequently, and use large irregular shape, flat bottom stones (not boulders or rocks) that forces the horse to navigate around the large stones to procure the feed. Stones must be large enough that it cannot be mouthed or picked up by the horse. The goal is to slow down the amounts of feed consumed per mouthful.
Another option is to soften the feed by adding water and mixing to an oatmeal consistency. The term gruel is used to describe this form. I had responsibilities for a lot of horses over the years but never had a horse choke on my watch. Identifying horses that are potential risk by their behavior or pecking order position and being studious on nutritional management fundamentals are important tools to reduce concerns with choke.