LEXINGTON, Ky. -- The 100-acre bluegrass pasture at the state prison where Tomo, a retired thoroughbred, spends most of his days grazing under the hot Kentucky sun is a long way from the glitzy, fast-paced racetracks where he grew up. At age 6, with a less than stellar career behind him, Tomo was headed to a slaughterhouse last year, like thousands of horses whose racing days have ended. But he is one of the lucky ones. He landed a slot at the Blackburn Correctional Complex, where inmates care for the horses as if they were their own. It was on...