NEW YORK (AP) — An aggrieved harness-racing bettor has gone to court to recoup more than $31,000 in winnings he said he was cheated out of when a doped horse won a race in New Jersey two years ago.

Leading figures in harness racing said they had never before heard of such a lawsuit, which accuses the trainer of fraud and racketeering. The general practice is to reallocate the purse to other owners in the event a winning horse is later proven to have been doped, but not to pay back bettors.

The trainer’s lawyer said the lawsuit was flawed, and that he might demand its retraction.

The lawsuit, filed Wednesday in U.S. District Court in New Jersey, represents an effort by People for the Ethical Treatment of Animals to open the gates for more litigation by bettors, which the animal rights group hopes would dramatically curtail illegal horse doping. PETA contends that injured horses are sometimes dying on the tracks because they were doped illegally or overmedicated to keep them running when they should be recuperating.

The lawsuit was filed on behalf of Jeffrey Tretter, an experienced gambler from Granite City, Illinois.

The lawsuit says Tretter placed wagers through an online betting site on a harness race at the Meadowlands Racetrack on Jan. 15, 2016. The horses he picked to place first through fourth instead finished behind Tag Up and Go, who had been a longshot in the race.

Meadowlands later revealed that Tag Up and Go had tested positive for EPO, a banned performance-enhancing substance, based on blood samples taken in December. As a result, trainer Robert Bresnahan Jr. was barred from competing at Meadowlands, but there was no redress for bettors such as Tretter.

According to his lawsuit, he correctly picked the horses that finished second, third, fourth and fifth behind the doped horse in a variety of wagers that would have paid a combined $31,835 if Tag Up and Go had been disqualified.

The lawsuit alleges fraud on the part of Bresnahan and the company that owned Tag Up and Go. It also alleges violations of the federal and state anti-racketeering laws known as RICO (Racketeer Influenced and Corrupt Organizations Act), contending that the federal law was violated because Bresnahan was engaging in interstate commerce.

The suit asks that Tretter be recompensed for his lost winnings in the race and be awarded additional punitive damages.

Bresnahan, who runs a stable in Manalapan, New Jersey, referred The Associated Press to his lawyer, Howard Taylor, who said the lawsuit would not hold up in court.

According to Taylor, the testing involving Tag Up and Go has no official standing in the U.S. legal system because it was conducted at a racing lab in Hong Kong. He also said the suspension imposed by the Meadowlands on Bresnahan was the act of a private business, and did not represent any official finding of wrongdoing by the trainer.

Taylor said he planned to contact the New Jersey law office representing Tretter, demanding that they retract the lawsuit and apologize to Bresnahan.

“If not, we’re looking into filing a suit for libel,” Taylor said.

In February 2016, Bresnahan issued a statement insisting he neither administered EPO to Tag Up and Go, nor authorized anyone else to do so.

“This news was a complete shock to me and obviously very upsetting,” he wrote.

Shortly after that statement appeared, Meadowlands announced that a second horse of Bresnahan’s had tested positive for EPO.

Bresnahan also was fined and suspended for 60 days for illegally administering the painkiller oxymorphone to a horse called Mr. Caviar in 2012, according to the Racing Medication and Testing Consortium.

The owner of Meadowlands, Jeff Gural, has been among the leaders in harness racing trying to curb doping. The Tag Up and Go doping case emerged through one of his initiatives, establishing “out of competition” drug testing that subjects horses to the possibility of testing at any time.

But he said unscrupulous trainers are constantly changing tactics to avoid detection.

“It’s a cat and mouse game, the same as in human sports,” Gural said. “They know what drugs are being tested for — they try to stay one step ahead.”

There has been some federal engagement in the fight against horse doping. For example, a federal prosecutor in Pennsylvania last year won the conviction of a horse trainer at Penn National race track on charges of conspiring with three veterinarians to fraudulently administer prescription drugs for her horses on race days.

There is also a bill pending in Congress that would establish a national anti-doping and medication authority for horse racing in the U.S., operated under the oversight of the U.S. Anti-Doping Agency, known as USADA. The bill, introduced in the House last year, has not advanced out of committee.

Gural said he supports the bill as a needed step toward standardizing rules that now vary among the 38 different racing jurisdictions in the U.S. Many leading harness racing figures oppose the bill, including Mike Tanner, CEO of the U.S. Trotting Association.

“There are too many holes in it,” said Tanner, who worries that the bill would impose significant new costs on owners to underwrite additional drug testing.

PETA is critical of horse racing, but is pushing for reforms rather than actively campaigning for an all-out ban. The group hopes the lawsuit will curtail doping.

“Horses continue to be drugged, bettors get cheated, and trainers get slaps on the wrist,” said PETA senior vice president Kathy Guillermo. “Maybe if they’re hit squarely in the wallet, they will pay attention and stop hurting horses.”

In this Nov. 20, 2013, file photo, letters spell out Meadowlands over top the new grandstand at the race track in East Rutherford, N.J. The CEO of Meadowlands, Jeff Gural, has been among the leaders in harness racing in trying to curb doping. Meadowlands revealed that Tag Up and Go had tested positive for EPO in 2016. The Tag Up and Go doping case emerged through one of his initiatives, establishing “out of competition” drug testing, which means horses can be subject to testing at any time, on the track or off. (AP Photo/Mel Evans, File)