Soledad O’Brien, Off-track Thoroughbred convert

On a morning earlier this summer, Soledad O’Brien failed to pick up the phone for a scheduled interview, calling back a short time later with effusive apologies. “I got dumped by my horse,” she said. “He got spooked, took a side step, and I fell off.” She is matter-of-fact about the experience, the result of a lifetime around horses, which began, as…