Almost Hopeless Horse — Kathryn Judson

When the Forresters' favorite cow horse has a colt, everyone assumes he'll be a good cow pony just like his mother. But Billy isn't good at any sort of ranch work. He's silly, friendly, and lots of fun - but the Forresters can't afford to keep a horse who doesn't earn his keep. So Mr. Forrester keeps trying to find something Billy can be good at. Children's fiction.