Harbinger's racing career looks over after he suffered serious injury on the gallops at Newmarket this morning.
The record-breaking winner of the King George VI & Queen Elizabeth Stakes at Ascot is believed to have a cracked a cannon bone, although this is yet to be confirmed.
Sir Michael Stoute's cahrge was due to have his next start in the Juddmonte International at York before a shot at the Prix de l'Arc de Triomphe in October for which he was 2-1 favourite.
