The stablemaster in Valentine is Samuel (Sam) Goode.
Running a large stable in a busy livestock town, selling and boarding horses, doing farrier work, and fitting tack keeps Sam very busy. While he is quite kindhearted and knowledgeable, he's nearly always extremely overworked and a little bit frazzled (with no time for your typical Valencrime shenanigans); however, this means he's almost always willing to offer work to someone down on their luck that isn't above shoveling shit (or shmud) for a few hours. He may not often have the time to speak to you for more than a minute, but there are never enough stablehands in a town like Valentine and he always appreciates good, honest business.