NEW YORK — Big Brown’s Triple Crown bid is finished. So is his undefeated career record.

In one mystifying run at the Belmont Stakes, Big Brown’s legacy disintegrated with racing’s 12th Triple Crown on the line in New York. The convincing Kentucky Derby and Preakness Stakes victories, the talk from his audacious trainer and brazen boasts out of the colt’s ownership group meant nothing once Big Brown finished dead last in a race won by 38-1 longshot Da’ Tara.

The bay colt that had a racing community wondering if he could be the straggling sport’s savior instead left a more unexpected question Sunday: What went wrong with Big Brown?

“Big Brown wasn’t Big Brown,” said Nick Zito, who trained long-shot winner Da’ Tara.

Right now, no one really has the answers to Big Brown’s woes.

Co-owner Michael Iavarone said Big Brown had a thorough examination after the race and again Sunday morning.

“There’s nothing physically that’s shown up,” he said, speaking by cell phone. “I’m as confused as anybody. The only thing we’re resorting to right now is the track might have been too deep for him and he didn’t like it out there.”

Iavarone said Big Brown’s problem feet, other than a loose left hind shoe, were not an issue.

“We’re perplexed,” he said. “Nobody can figure this one out.”

There are no obvious answers, and Big Brown might undergo blood work or need X-rays to figure out exactly why he was flat at the Belmont.

Jockey Kent Desormeaux knew Big Brown was finished as he turned for home and eased up in the homestretch.

“When I got outside going into the first turn, I said, ‘This is it, the race is over, I got it,” Desormeaux said.

Except Big Brown didn’t respond.

Da’ Tara opened up a clear lead turning for home, while Big Brown angled to the far outside under restraint. Big Brown still wanted to run, but Desormeaux knew it was over and focused on getting the colt home safely.

Desormeaux, who fell a Belmont win shy of the Triple Crown for the second time in 10 years, said the horse had nothing left by the end of Saturday’s race.

No energy, no run.

And to think, trainer Rick Dutrow Jr. proclaimed victory was a “foregone conclusion.”

Dutrow also said the colt’s patched left hoof was a “non-issue,” and the colt showed no signs of favoring the hoof after the race. Exercise rider Michelle Nevin led him in circles outside Barn 2 on Sunday and he appeared fine. Big Brown got a bath, playfully nipped at a leather lead and looked no different from Friday when he was viewed as horse racing’s Next Great Hope.

Big Brown walked perfectly on his patched left front hoof.

Anyone looking for answers at the barn came up as empty as Big Brown in the Belmont. Dutrow — whose bluster couldn’t be stopped the entire Triple Crown season — no-showed Sunday. Nevin also declined to talk about how Big Brown could be beaten by eight other horses.

Dutrow was criticized after acknowledging he used an anabolic steroid on Big Brown, then said last week that the horse hadn’t had a dose of Winstrol since April. The drug is legal in the three states where the Triple Crown races are run.

“By this time next year, steroids will be banned from horse racing competition,” Alex Waldrop, president and chief executive of the National Thoroughbred Racing Association, said Sunday. “The Big Brown campaign only underscores the need to act to ensure the safety of the horses and to remove any suspicion concerning steroid involvement with our stars.”

On the advice of Hall of Fame trainer Bobby Frankel, Dutrow had said he was going to reduce Big Brown’s dose of electrolytes, which are salts such as sodium, chloride and potassium that help prevent dehydration. It wasn’t clear whether he followed through on that plan before the Belmont.

Big Brown was taking Lasix, a legal anti-bleeding medication that can cause a horse to become dehydrated. Highs were in the 90s and there was oppressive humidity Saturday. Several horses throughout the day were sweating excessively and needed to be cooled off with buckets of water and sprayed with hoses after they ran.

Racing desperately needed the jolt a Triple Crown would have provided. Instead of the Big Brown magazine covers and human connections hitting the talk show circuit, the sport will likely fade back to relative obscurity.

It’s now 30 years and counting since Affirmed was the last horse to sweep the Kentucky Derby, Preakness and Belmont.

“Should they change it? I say absolutely not,” Zito said. “I don’t think so. It’s one of the toughest things to do in sports.”

Zito has Da’ Tara pointed toward the Travers Stakes where a rematch with Big Brown potentially awaits. Iavarone said that unless his horse is at risk of injury, Big Brown will maintain his training schedule and prepare for the Travers in August at Saratoga.

Big Brown, of course, is worth millions to Iavarone and his other two owners. They’ve already locked up an estimated $50 million deal for his breeding rights with Three Chimneys Farm in Kentucky.

Dutrow has said he’d like Big Brown to run this fall in the Breeders’ Cup Classic in California.

Big Brown could finally look eye-to-eye with Japanese import Casino Drive in the Breeders’ Cup. Casino Drive has a bruised left hind horse and was scratched Belmont morning. He was set to be shipped back to Japan on Tuesday, but the colt was expected to return to the States to race in the Breeders’ Cup.

Maybe by then, there will be answers for what ailed Big Brown. Zito could only wonder what Dutrow was thinking a day after his biggest professional disappointment.

“He knew he knew he had something special,” Zito said. “He was very confident. He knew he had something on his hands that was really tremendous.”

Now all Dutrow has are a whole lot of questions.