Johnny:

Wheel may have been referring to "The Kid", by Pete Axthelm, the story of
Cauthen's Triple Crown win with Affirmed.

Also recommended "Wild Ride" by Ann Hagerdorn Auerbach, the story of how one man
single handedly bankrupted Calumet Farm. Determine for yourself if foul play was
involved in the death of Alydar.

In terms of individual racehorses, I really enjoyed "The Kingmaker: How
Northern Dancer Founded a Racing Dynasty". I do not recall if the author told of
"The Shot Heard Round The World", which was Doc Harthill administering LASIX to
Northern Dancer before the Derby years before LASIX was widely used (legally or
illegally).