“Every horse story is a love story,” writes Jane Smiley, who has loved horses for most of her life and owned and bred them for a good part of it. To love something is to observe it with more than usual attention, and that is precisely what Smiley does in this irresistibly smart, witty, and engaging chronicle of her obsession.In particular she follows a sexy filly named Waterwheel and a grey named Wowie (he “tells” a horse communicator that he wants it changed from Hornblower) as they begin careers at the racetrack. Filled with humor and suspense, and with discourses on equine intelligence, affection, and character, A Year at the Races is a winner.