Belmont Stakes winner Union Rags has been retired due to the suspensory injury he suffered earlier this month.
The three-year-old colt failed to make an impression in the Kentucky Derby, but claimed the last leg of the Triple Crown with a narrow victory at Belmont Park.
Michael Matz's colt was due to make his next start in the Haskell Invitational at Monmouth Park on 29 July until a leg injury was discovered last week.
Owner Phyllis Wyeth feels that it would be in the best interests of Union Rags to pursue a career at stud, rather than being brought back to race next year.
Wyeth's advisor, Russell Jones, said: "I spoke to Phyllis. She discussed it with Jamie (her husband) and it was all about the risk factor.
"This was a time to make the tough decision. The horse is very much in the limelight as far as breeders go at this moment, and they felt like it would be a challenge and a risk to be back in this position next year.
"There was a lot of risk involved because if they did not get him back to where he is now, it would be at a significant cost."
The Classic crop in the US lost Kentucky Derby and Preakness Stakes winner I’ll Have Another to retirement earlier in the season when his career was prematurely ended by injury.