California Chrome may not race again with a bruised cannon bone ruling him out for the rest of the season and and stud deals being discussed.
The injury was detected in X-rays taken on Sunday as part of a thorough check of the four-year-old for a potential sale to breeders.
The winner of the 2014 Kentucky Derby and Preakness Stakes, California Chrome has been at Arlington Park outside Chicago since Tuesday when he arrived back from an aborted campaign in England.
He was scheduled to run in the Arlington Million on August 15.
“He’ll be fine,” trainer Art Sherman told the Daily Racing Form.
“It’s not life-threatening or anything, but it looks like he’ll be out for the rest of the year.
Sherman said he was unsure about California Chrome’s racing future but he believed the prospective sale had been called off.
He said the owners were considering whether the horse would race again.
California Chrome has not raced since finished second in the $10 million Dubai World Cup on March 28.
He went straight to England from Dubai but a bruised hoof ruled him out of the Prince Of Wales’s Stakes at Royal Ascot.