Gronkowski, the Kentucky-bred 3-year-old named after the New England Patriots star, will miss the Kentucky Derby, his ownership group said Monday on social media.
"We very much regret that #Gronkowski will miss the @KentuckyDerby after spiking a fever over the weekend and being treated with antibiotics. He can't make the long journey to Louisville but is doing well," Phoenix Thoroughbreds said in a tweet.
Gronkowski, who trains and races in England, qualified for the Kentucky Derby after finishing first in a new points system for European horses.
Last week Rob Gronkowski joined Phoenix Thoroughbreds for a stake in the horse's ownership and was expected to meet his namesake before the Derby on May 5.
Phoenix Thoroughbreds is a Dubai-based “investment fund” that dropped millions of dollars at sales around the world last year.
Kerri Radcliffe, a bloodstock agent, purchased the horse on behalf of Phoenix Thoroughbreds for 300,000 British pounds (roughly $425,000 U.S. dollars) at the Tattersalls auction for 2-year-olds in training last year. Gronkowski has a 4-1-0 record in six starts.
“I loved the big rangy horse, just basically built like a tank,” Radcliffe told USA TODAY this month. “He is built in the equine form of Gronk.”
Racingpost.com first reported Monday morning that Gronkowski had a setback over the weekend, putting his Derby participation in jeopardy.
Gronkowski was immediately treated with antibiotics and the illness seems minor, the Courier-Journal reported, citing a news release.
The NFL player tweeted Monday that he fully supported "what is best for the horse" and was looking forward "to see him race again very soon."
