It's time for the Dream Horse to die.
It is. The Dream Horse is an archetype distressingly common in children's literature, spawning awful books like this one for generations of obsessed little riders. Young teen Sarah Wagner is a Talented Horseless Rider who, through the interventions of an Amazingly Kind Adult, is gifted with a choice of four horses just off the track. The one she picks, a gelding of remarkable, valuable breeding who never raced because he is so poorly behaved under saddle (a fantastic choice for a kid!), is immediately found to have a reversible medical condition (somehow missed by the track vets) that will made him tractable. A real, honest teenager would at this point immediately return the horse for one of the others—his racing career is presumably restored, and since she's only owned the horse one day and never ridden him, he's the equal to her of the others. But no. This is a Dream Horse. Our Heroine must throw temper tantrums until she can keep the horse; the adults, instead of counseling her toward appropriate moral behavior, applaud her Loyalty and Perseverance. There's also a Poor Little Rich Girl, a Stalwart Friend, an Irascible Groom and a Token Boy Rider. Despite the liberal use of tropes, far too much of the prose is unnecessary, laborious detail.
Worse, it's first in a series. (Fiction. 10-13)