It has become an all-too-common scenario: a thoroughbred suffers a ghastly injury before a packed grandstand and a national television audience and has to be euthanized by injection on the track. This past Saturday at Saratoga Race Course, an undefeated colt named New York Thunder was just strides from winning a $500,000 stakes race when he stumbled and unseated his rider.

The jockey, Tyler Gaffalione, got up. New York Thunder had to be put down after shattering his left front fetlock.

It was the 12th horse fatality — the eighth while racing — at the Saratoga summer meet. Combined with the deaths of a dozen horses last spring at Churchill Downs, including two on Kentucky Derby day, the fatalities have brought renewed scrutiny of horse racing and again left owners, trainers and racetrack executives struggling to reassure the public that racing is safe for its human and equine athletes.

In the wake of the deaths, New York racing officials have vowed to spend millions on PET and CT scans and outfit horses with sensors in the hopes of diagnosing pre-existing injuries before they become fatal. And a synthetic racing surface, which equine injury data shows to be significantly safer than dirt and turf tracks, is being installed for winter racing at Belmont Park and is being considered for both Aqueduct and Saratoga.

“We can strive for zero fatalities and part of that is aggressive imaging, synthetic surfaces and sensor tracking,” said David O’Rourke, the chief executive officer and president of the New York Racing Association. The association is in the process of acquiring the diagnostic equipment and hopes to have it in place soon.

Also, the director of the Horseracing Integrity and Safety Authority, which oversees racing safety nationwide, said the authority will soon implement a rule lengthening the time horses must wait to race after they have received a steroid injection. Steroids can mask pain and may cause horses to run hard even when they are hurt.

In recent years, racehorse deaths have deepened the sense of crisis in an industry that is dwindling in popularity as racing fans turn to other sports and forms of gambling.

In 2019, 30 horses died at Santa Anita Park in California in a span of six months, creating national headlines and drawing the scrutiny of state lawmakers and animal rights activists. In response, state regulators and racing officials strengthened rules regarding the use of riding crops, medications for horses, education for trainers and jockeys, track safety and recuperation policies for injured horses.

The reforms appeared to be effective. Last year, 12 horses died at Santa Anita. Thoroughbred fatalities throughout California fell 54 percent from 2019 to 2022.

Dr. Scott Palmer, New York’s equine medical director, said the number of fatalities had been declining in New York as well.

Nationally, since 2009, the Jockey Club has kept a database to track fatal breakdowns on American racetracks and analyze how they can be prevented. That first year, thoroughbreds had fatal injuries at the rate of two per 1,000 starts.

The rate of fatal injuries has declined every year for the last four years. In 2022, the rate was 1.25 deaths per 1,000 starts.

But the high-profile breakdowns at big races have occurred when casual fans are tuned in and, ultimately, turned off. While 12 horses died at Saratoga the previous two years, a majority of the deaths occurred during training hours. This year, eight horses have died while racing.

“The Kentucky Derby teed this up,” Palmer said, referring to the repeated and highly publicized deaths at Churchill Downs in May. The pattern continued at the Preakness Stakes in Baltimore, where Havnameltdown — trained by Bob Baffert, the most recognizable figure in the sport — broke down in a race preceding the second leg of the Triple Crown.

“It’s been awful,” Palmer said.

New York Thunder, the horse that broke down in front of the Saratoga crowd, was brilliantly fast but prone to injury, according to his veterinary records obtained by The New York Times.

The horse’s trainer, Jorge Delgado, declined to comment on his handling of the colt, the third of his horses to die since July 27. The colt’s London-based owner, Kia Joorabchian, could not be reached for comment.

After winning his first two races last year as a 2-year-old, first on a synthetic surface and then on turf, New York Thunder had a slow start to his 3-year-old season. He spent two weeks in the spring on the Kentucky vet’s list described as “lame,” according to vet records, making him ineligible to compete. Horses are put on the vet’s list when they are deemed unsound by regulatory veterinarians or have undergone certain procedures that require extra time or scrutiny.

He returned to racing on April 30 at Woodbine Racetrack in Toronto, easily winning a stakes race on a synthetic surface.

In June, Delgado entered New York Thunder in the Woody Stephens Stakes on the undercard of the Belmont Stakes. But the horse was scratched by state veterinarians the morning of the race because he was injured, according to the vet records. No other information was given in the records.

On July 14, New York Thunder went on the vet’s list again for two weeks after he was given a joint injection, the records say. The injection was allowed under rules set by the national horse racing authority, which was created by Congress 2020 to oversee the sport. It is common for trainers to inject horses with steroids to battle inflammation and reduce pain.

On July 28, the colt came off the vet’s list and won the Amsterdam Stakes on dirt in Saratoga by an eye-catching seven and a half lengths.

Racing a horse two weeks after it has received an injection is allowable under the rules but controversial in the sport. Before the national racing authority took over antidoping and medication control on May 22, California had a rule that prohibited steroid fetlock injections within 30 days of a race.

Before the rule went into effect, the state had 83 catastrophic fetlock failures in 20 months. Afterward, it had 24 in the next 19 months.

Dr. Greg Ferraro, the chairman of the California Horse Racing Board, said the use of medications too close to a race limits the ability of regulatory veterinarians to identify pre-existing conditions that may progress to catastrophic injuries.

“Fourteen days is a step backward,” said Ferraro, a former racetrack veterinarian. “If you put any athlete in significant training, the health of joint disintegrates, you can’t slow it down, but you can speed it up by putting corticosteroid in the fetlock. You inject to run. That culture needs to be eliminated.”

The culture still existed when New York Thunder was racing this summer. On Aug. 12, two weeks before the H. Allen Jerkens Memorial Stakes in Saratoga, he again received a joint injection.

On the day of the Jerkens Memorial, the colt bounced out of the gate and led every step of the seven-furlong sprint. He was gliding like a swamp buggy, five lengths ahead, as the finish line approached. There were more than 48,000 people at the racetrack for the 154th running of the Travers Stakes, or “Midsummer Derby,” later that day.

A full-throated roar powered New York Thunder down the stretch.

And then the colt seemed to come apart, crumpling to the ground and tossing Gaffalione. Gasps and groans turned to silence. The horse ambulance arrived; a screen was raised. Tear-streaked faces in droves headed for the exits.

It seemed a cruel replay of the scene three weeks earlier, on another big day with a national broadcast audience, when a filly named Maple Leaf Mel fatally broke down just yards from the finish line.

Lisa Lazarus, the chief executive of the national authority, acknowledged that the rule in place and the process for determining a horse’s soundness failed New York Thunder.

“There’s two ways to look at a horse — on paper and through his vet records and past performances and in person on the day of the race,” Lazarus said. “The regulatory vet can only act on what they see on the day and in the moment.”

In the final days of the Saratoga meeting, which ends Monday, a veterinarian from Lazarus’s staff is examining the records of horses entered in every race. Lazarus anticipates that the authority, along with state racing associations, will create a review panel to daily determine the fitness of horses entered to run that day, much like the model that California employs.

Lazarus said the authority would adopt the California rule of banning steroid fetlock injections within 30 days of a race.

Changes in racetracks are also likely to help. Horses break down 0.41 times per 1,000 starts on synthetics compared with 0.99 times on turf and 1.44 times on dirt, according to the Jockey Club’s database.

Mark Casse, a Hall of Fame trainer in the United States and Canada, said he has trained or raced horses at least 150,000 times on Woodbine’s synthetic racetrack over the past decade. He said synthetic tracks are more consistent and have more give, especially in inclement weather.

“It’s been safer year after year after year,” Casse said. “What happens on dirt is that the preferred way to win is to train for speed and get to the front. Getting dirt kicked in their faces discourages horses. On synthetic, it’s not as fast as you can, it’s more tactical. Speed on hard dirt kills.”

Santa Anita and Del Mar in California and Keeneland in Kentucky experimented with synthetic tracks more than a decade ago. Breakdown rates fell significantly, but complaints from trainers and breeders skyrocketed. Trainers said they saw more soft tissue and hind injuries. Breeders were afraid horses that performed well on synthetics might not transfer that quality to dirt, diminishing the value of their stallions.

“We, as an industry, do not like to change,” Casse said. “But if we continue to cling to tradition, we will be out of business.”

With the amount of scrutiny on horse racing, however, Casse believes the sport is at a crossroads and without change will go out of business.

“We have to be better,” Casse said. “I’m not sure that I’m as proud to be a horse trainer as I used to be.”