The modern backbone of an ancient sport quivers and quakes amid a relentless fear hovering at the barns of American horse tracks. The fear, almost like some smothering yet invisible blanket, howls at wake-up, lingers through the rigors in the stables and harasses eyelids at bedtime. The backbone, the laborers from Mexico and Guatemala and other lands who feed, water, walk, wash, massage, sustain, coddle and converse with the racehorses, finds the fear even in periphery: