I'll Have Another has been declared a non-runner for the Triple Crown's final event, the Belmont Stakes (gr. I) according to trainer Doug O’Neill.

O’Neill said the colt has a tendon injury that could threaten his racing career. According to owner Paul Reddam heat was discovered in one of I'll Have Another's legs the afternoon of June 7. Although Reddam added that the colt jogged fine on the morning of June 8, a subsequent scan after his trip to the track showed inflammation and the decision was made to scratch the son of Flower Alley from the Belmont.

"He's been doing great. It's a freakish thing," O'Neill said. "It's like a human athlete. When you give 110% every time you step on the court or the track, it's something that can happen. I'd been hoping and praying that he'd stay healthy."

The injury ends a remarkable season for I'll Have Another. Like Affirmed, I'll Have Another prepped for the Triple Crown with a victory in the Santa Anita Derby (G1). I'll Have Another then overcame the 19 post position in the Derby, surging past Arkansas Derby (G1) winner Bodemeister in deep stretch to post a clear victory. Those two hooked up again in the Preakness, where I'll Have Another edged past his rival in the final strides for a neck victory.

After winning just one of three starts last year, I'll Have Another had won all four of his races this season, all stakes. He opened the year with a 43.30-to-1 upset victory in the Robert B. Lewis Stakes (G2) at Santa Anita Park.

I'll Have Another is the first classic winner for O'Neill, Reddam, and jockey Mario Gutierrez.

"I'm not disappointed," Gutierrez said. "We have to take care of the horse."

The 25-year-old rider burst onto the scene with I'll Have Another, to date, his only Grade 1 winner.

"This horse means the world to Mario," Reddam said.

I'll Have Another was the morning-line 4-to-5 favorite.

"It's a shame, it's sad for the sport. It would have been a great race," Romans said. "It's very disappointing for [I'll Have Another], for his connections, and for the sport, and I was hoping to make history by beating him."

Other prominent racing personalities also took to social media on Friday morning to share their thoughts on the shocking development.

"Sad to hear about [I'll Have Another]. Reminds me of Eskendereya," tweeted the official Zayat Stables page of owner Ahmed Zayat. Eskendereya was the early favorite for the 2010 Kentucky Derby, but was withdrawn the week of the race with an injury and later retired.

Zayat, whose Bodemeister finished second to I'll Have Another in the Kentucky Derby and Preakness, will be represented in the Belmont by Paynter.

"So sad," tweeted retired Hall of Fame jockey and HRTV commentator Gary Stevens. Later, he posted, "Hats off to Doug and the team."