ARCADIA, USA--Against the most stunning backdrop in world racing, just as the pre-dawn sky started to pinken with promise, a metaphorical dark cloud was cast across Santa Anita racetrack. Practical Move (Practical Joke), a leading contender for the Breeders' Cup Dirt Mile, collapsed and died of an apparent heart attack on his way back in from exercise in front of onlookers on the apron. The screens arrived eventually, but not soon enough to remind those present of the occasionally desperate nature of the sport we love, and how such a...