as a reiner

[frindle]

Hello. I wonder what 'a reiner' means in these sentences below.
Please help. Thank you.

"His name is Dash," her dad said. "He's not working out as a reiner.
I was planning to sell him, but he might make a good barrel racer."

[BobK]

Sounds to me like something to do with racing horses - by which I mean 'racing HORses' not 'RAcing horses'.

b

PS Conceivably - just my guess - a 'reiner' would be one of the front two horses in a team, one who has to take directions through the reins rather than just following the leader.

[frindle]

Thanks!^^