Editor's note: After 60 Minutes aired a segment called "Horse Racing Reform?" on its Sunday night broadcast, Dark Hollow Farm's JoAnn Hayden posted a letter she had written to 60 Minutes on her Facebook page and urging friends and racing industry members to do the same. She writes: "I have always felt proud and grateful to be part of Maryland's thoroughbred racing community. Over the past 50+ years my circle of friends, employees, trainers, and colleagues have been exemplary humans who have provided the best care for my horses and...