(CNN) -- The Kentucky Derby resides on a summit of high-society pomp.
But with the clink of champagne glasses, the flutter of feather-bedecked sunhats and the drumming clomp of purebred hooves just weeks away, animal rights advocates may have turned over a rock, revealing an alleged equine hell beneath it.
Injured horses compete under peak demands, PETA said. It alleges they are doped against the excruciating pain of worn-out joints, hooves with holes and bleeding lungs.
Their handling and training are so grueling, prized chargers drop dead before making it to the racetrack, People for the Ethical Treatment of Animals said.
The group targeted one of America's top horse trainers, Steve Asmussen, and his main assistant, Scott Blasi, in a monthslong undercover operation that included video recorded clandestinely.
Though the sting singled out the men, the group said what it found is "standard practice" in the horse racing industry, where "death and injuries are business as usual."
PETA backs its allegations with a lengthy report and hidden camera video that the activists posted to YouTube on Wednesday.
The images of alleged doping are grueling. They are matched by what appears to be incriminating conversations -- laden with profanity -- with workers who appear disgusted by the suffering of the animals.
The videos are edited.
Racehorses receive so much medication that they are often called "chemical horses," PETA said.
Horses in Asmussen's care received a thyroid drug to "speed up metabolism," Lasix to prevent lung bleeds during overexertion, muscle relaxants and sedatives, the group alleges.
It did not say whether the treatments were legal or customary.
PETA has a reputation for a sometimes puritanical approach to animal rights and protection, and it advocates a vegan lifestyle. The group said it has filed 10 complaints against Asmussen and others working with him in Kentucky and New York.
Authorities in those two states are taking the allegations seriously.
The Kentucky Horse Racing Commission and the New York State Gaming Commission have opened investigations based on the undercover operation.
"The behavior depicted in the undercover video and supporting materials is disturbing and disgusting," said veterinarian Scott Palmer of the Gaming Commission.
Clark Brewster, the attorney representing Asmussen and Blasi, told CNN affiliate WAVE that his statement Wednesday in The New York Times will be the statement for all the media.
"It is certainly a surprise to Mr. Asmussen and Mr. Blasi," the statement published in the Times said, "that anyone would deceptively get a job and keep surveillance and their notes on their conduct for the agenda of others. They will reserve comment with regard to any accusations until they have had the opportunity to fully review them. Then they will respond factually."
CNN has reached out to Brewster for comment.
PETA also accused Asmussen of paying less than minimum wage and hiring undocumented workers.
The recordings and allegations also tarnish the shine of two of the country's top horse racetracks.
PETA said its activist obtained access to Asmussen by going to work for him, and made the recordings from April to August 2013 at the Churchill Downs racetrack in Louisville, Kentucky -- the home of the Derby -- and at New York's Saratoga Race Course.
The New York Racing Association, which conducts racing at the Saratoga Race Course, said it was concerned about the allegations brought to the Gaming Commission.
"The New York Racing Association takes the health and well-being of its equine athletes very seriously," the group said. "We pledge to continue to work in partnership with the Gaming Commission and all industry stakeholders to promote the safety, integrity and transparency of our racing."
Churchill Downs issued a statement expressing concerns about the health of horses.
"This has always been a topic of great importance to us, and we've made long-term and far-reaching commitments to incorporate health and wellness measures for every race, every day," it said.
The racetrack describes the Kentucky Derby as "the greatest two minutes in sports."