
The trainer told stewards the colt would have "immediate treatment" for the condition.
McEvoy was hopeful Sun City would be able to recover in time for the Magic Millions, but late on Wednesday advised stewards the colt would require further vet treatment and was out of the rich race.
The withdrawal of Sun City will be helpful to the fortunes of McLachlan Stakes runner-up Rome, who is on the borderline of a start with $44,200 in prizemoney.