A Coolmore representative has confirmed that dual Derby winner Australia has been retired to stud with immediate effect.
The three-year-old had been due to race at the QIPCO British Champions Day at Ascot next Saturday.
However, having recently discovered a hoof problem, those connected with the Galileo colt have decided that the time was right to retire.
"Unfortunately Australia developed a problem in his right-hind hoof during the week," Coolmore's UK representative Kevin Buckley told Channel 4 Racing.
"Following consultation between the resident farrier at Ballydoyle, our vet, John Halley, and the respective owners, the decision was made yesterday to retire him to Coolmore."
Australia won five of his eight outings, which in turn earned £2m in prize money.