More than two dozen horse racing industry employees were charged Monday with participating in “a widespread, corrupt” doping scheme, the latest black eye for the troubled sport.

Federal prosecutors brought charges against 27 people in a far-reaching operation involving performance-enhancing drugs, alleging that racehorse trainers, veterinarians and others manufactured, distributed and received “adulterated and misbranded PEDs and … secretly [administered] those PEDs to racehorses,” according to the charging documents.

The investigation found that the trainers and vets were able to deceive horse racing regulators by administering PEDs that were “difficult or impossible to detect in anti-PED tests,” some of them unapproved and administered using methods “that can injure and, in extreme cases, kill the horse.” The drugs also masked the horses’ ability to feel pain, causing the animals to overexert themselves during exercise.

“These substances stimulated endurance, deadened nerves, increased oxygen intake and reduced inflammation,” William F. Sweeney Jr., assistant director in charge of the FBI’s New York field office, said Monday at a news conference. “What actually happened to the horses amounted to nothing less than abuse.”

The indictments were handed down amid a time of increased scrutiny on the industry, which has seen a rise in fatal racehorse injuries over the past year. In January, a House of Representatives committee heard testimony from supporters of the Horseracing Integrity Act, which would establish an independent, private nonprofit corporation that would administer an anti-doping program for racehorses.

Graham Motion, who trained 2011 Kentucky Derby winner Animal Kingdom and is an advocate for the act, wrote Monday on Twitter that it was “a sad day for racing but a long time coming."

“If it happened in any sport it would be disappointing, and when you’re talking about horses being put at risk, it’s even more troubling,” Motion said in a telephone interview.

“Look, it’s a sad day for the sport because it’s sad to know that there are people who are prepared to go to these lengths to cheat in our sport,” Motion added. “Let’s face it. It’s like any sport. We’re no different than any other sport in that respect. It’s a shame that it’s taken this long to catch these guys, who clearly, according to the indictments, have been using some pretty dramatic medications.”

Among those charged was trainer Jason Servis, who was accused of “orchestrating a widespread scheme of covertly obtaining and administering adulterated and misbranded PEDs” to “virtually all of the racehorses under his control.” One of Servis’s horses, Maximum Security, crossed the finish line first in last year’s Kentucky Derby, but he later was disqualified for interference. Last month, Maximum Security won the inaugural Saudi Cup, the sport’s most lucrative race.

The investigation covered a period beginning in January 2017 and continuing through January of this year, and it involved races across the country. FBI agents on Monday raided barns at Gulfstream Park West, near Miami, and the Palm Meadows Training Center in Boynton Beach, Fla.

“By evading PED prohibitions and deceiving regulators and horse racing authorities, among others,” the indictment alleges, “participants sought to improve race performance and obtain prize money from racetracks throughout the United States and other countries, including in New York, New Jersey, Florida, Ohio, Kentucky, and the United Arab Emirates.”

Jorge Navarro, a trainer whose horses have earned close to $35 million over his career, is at the center of the alleged scheme. Federal prosecutors allege Navarro gave a horse named X Y Jet adulterated and misbranded performance-enhancing drugs before wins in Florida and Dubai last year that earned $1.5 million. The 8-year-old X Y Jet died of a heart attack in January after a career in which he earned more than $8 million in purses over 26 starts.

Veterinarians Erica Garcia, Seth Fishman and Gregory Skelton were charged as accomplices to Navarro; prosecutors allege they either illegally manufactured the PEDs or illegally administered them at Navarro’s direction. A number of other people were charged with helping Navarro obtain, ship and administer the drugs.

In 2017, Navarro was fined $10,000 by the New Jersey Racing Commission for “conduct extremely detrimental to racing” after a video surfaced in which he was heard suggesting the use of illegal substances while rooting on a horse, trained by Jorge’s brother, Marcial, at Gulfstream Park in Florida. Jorge Navarro’s horses were banned by tracks in Delaware, Maryland and Indiana after the fine was levied.

At least two of Navarro’s horses tested positive for cocaine and other drugs in 2017, though the trainer maintained that the blood samples were contaminated.

Trainer Nick Surick also was charged for administering a PED called “red acid” that reduced inflammation in horses’ joints, thereby improving race performance. The PEDs used by the trainers in the indictment were not approved by the Food and Drug Administration for use on an animal and were designed not to show up on drug tests, according to prosecutors. They also featured false or misleading labels, using the terms “for research purposes only” or “homeopathic.”

In an intercepted telephone call recorded on Feb. 1, 2019, Surick implicated Navarro in a conversation with defendant Michael Tannuzzo, saying that Navarro secretly disposed of the bodies of horses that had died under his care.

“You know how many f----- horses [Navarro] f------ killed and broke down that I made disappear?” Surick allegedly said. “You know how much trouble he could get in … if they found out … the six horses we killed.”

A total of four indictments were handed down Monday. One accuses veterinarian Louis Grasso and others of manufacturing and distributing customized PEDs and says trainer Thomas Guido III obtained and administered the drugs to racehorses. Another says Sarah Izhaki and daughter Ashley Lebowitz distributed an adulterated and misbranded version of the drug erythropoietin, known in the industry under the brand name Epogen or the shorthand “epo.” The women also are accused of selling a masking agent nicknamed “the Devil,” which Izhaki described in a recorded telephone call with a confidential informant.

“You put it in the horse, you can use coke; it will come back negative,” she said.

A final indictment accuses Scott Robinson and Scott Mangini of operating an “online marketplace” at which racehorse owners and trainers could obtain misbranded and adulterated PEDs.

At a news conference Monday, Geoffrey Berman, the U.S. attorney for the Southern District of New York, said additional charges could be forthcoming.

"What’s most sad for our sport is that we haven’t been able to police our sport ourselves,” said Motion, the trainer. “That’s why I’m a big supporter of the Horseracing Integrity Act, which is something that we desperately need.”

Kyle Melnick contributed to this report.