If dogs can have costumes, then so can every other animal; the Horse Tailor is a company that specializes in costumes custom-fit to your horse.
Perhaps the only thing funnier then a pint-size Pug Superman is a giant horse-sized Superman. The Puerto Rican company will ship your horse costume to you--all you have to do is supply its measurements. If I had a horse, I would be buying everything the Horse Tailor made.
Implications - Pet owners are constantly on the search for the newest and most interesting releases for their beloved animals. Companies should make things like costumes and accessories available for animals of any kind, not merely for domesticated cats and dogs.