The trainer of Nyquist says the Kentucky Derby winner is sick and won't run in the Belmont Stakes on June 11.
Doug O'Neill said Tuesday that Nyquist is "out because of sickness."
Nyquist's bid for a chance at the Triple Crown ended when he finished third behind Exaggerator in the Preakness at Pimlico Race Course on Saturday.
O'Neill's assistant Jack Sisterson said from Baltimore that the colt's blood work came back and showed an elevated white blood cell count. He said "we just want to do right by him and get him to 100 percent."
When he's healthy again, the plan is to ship him back to California, with a summer schedule that could include the Travers Stakes at Saratoga.
In 2012, O'Neill's Derby and Preakness winner I'll Have Another was retired the day before the Belmont with a tendon injury and missed a Triple Crown chance.