Keeping Captain by N. L. Sharp is a great book for horse lovers of all ages.
Carly and her horse Captain have been champs at the local barrel racing circuit. Until she finds out they will be moving and her dad has promised to sell Captain to a schoolmate. So Carly's plan is to have Captain lose his races so maybe they won't want to buy him. But her plans fall apart, and in the end she learns what is really important for Captain.