Don Cossack's trainer Gordon Elliott has confirmed the 10-year-old, owned by Michael O'Leary's Gigginstown House Stud and who had been working his way back to the track next month, had instead been retired.
Elliott told his Betfair blog:
I am very sad to report that Don Cossack has suffered a setback and will now be retired.
"We found that he had a bit of heat in his leg yesterday and we've made the decision to call time
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