As Will Rogers said, the best doctors in the world are the veterinarians-because their patients can't talk. "And that's true," says Gary Lavin. "But at the same time, they don't lie to you either. So that gives us an advantage right there." His long intimacy with the physical structure of the Thoroughbred has taught Lavin to marvel, above all, at those intangibles housed within. Instructively, in fact, this doyen of racetrack veterinarians has observed a correlation between their performance as athlete and as patient. Ruffian, sadly, was an exception. Otherwise,...