Kentucky Derby winner Nyquist will miss the Belmont Stakes because of a high white blood cell count.

The colt's bid for the Triple Crown ended when he finished third in the second leg, the Preakness States on Saturday, as the odds-on favourite.

He succumbed to a fever on Monday and has since been recovering at Pimlico Race Course in Baltimore.

"He's out because of sickness," trainer Doug O'Neill said.

Although Nyquist appeared to be improving on Tuesday morning, the decision was made to withdraw the colt from the Belmont Stakes in New York on June 11 following the results of his latest blood work.

"There was a slightly elevated white count and we took his temperature again and that was slightly elevated," O'Neill's assistant Jack Sisterson said.

"So I spoke to Doug and Doug wants to do what's best for Nyquist and get him back 100 per cent health-wise here at Pimlico and then fly him back to California.

"We're not sure exactly the day we will do that but Nyquist will tell us when he's ready."

Exaggerator won the the Preakness Stakes with Nyquist suffering his first defeat at his ninth start.