Just like the title says, Halloween costume ideas for barrel race, for an open runner (i.e. not a kid, LOL). The horse is grey, if that helps with ideas. Nothing too extravagant but something fun!
Since he's gray, you could make him a shark; a fin for his head and a tail and you could be a mermaid on his back! Maybe even a bloody one. Or be simple and you could be a mermaid and he could be a "sea horse". Lol