I can understand that the incessant rains may have loosened the track surface and increased the resonance from the hard base, and therefore contribute to the number and gravity of injuries.
However, there is a factor which everybody in the U.S. seems to ignore: that these injuries become fatalities could possibly be due to the fact that horses are training on bute. Pain is nature’s warning signal, and if you blunt or mute that voice, you are looking for trouble.
The modern Thoroughbred, through selection, has evolved into such a brave and devoted animal, that he will perform through the pain barrier, but any discomfort will shorten his gait and/or action, and tell his handlers that he is hurting. If you add painkillers to this resilience and abnegation, you should not be surprised to get “catastrophic breakdowns” as they are called.