Thomas Chippendale's trainer Lady Cecil said she was "heartbroken" at the horse's death following his Hardwicke Stakes win at Royal Ascot.
Lady Cecil, whose husband Sir Henry Cecil was honoured during this year's Queen's Vase, said the colt was "in good form" leading up to the race and enjoying himself".
She continued: "He loved and enjoyed it all - it's heartbreaking. We had never been happier with him beforehand. We're just devastated.
"The horse and jockey seemed fine so I wondered what had happened. It was quick so the horse wouldn't have felt anything.
"We've gone from one emotion to the other, from a real high to a real low".
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Even the help of rain delays could not save England's desperate attempt to push for a draw in Perth as the hosts claimed the series win.
Guillier conceded a "severe defeat" defeat to his supporters as the result came in.
The outage struck Hartfield-Jackson Atlanta International Airport at around 1pm local time, stopping all outgoing flights.