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.”

After running for 60 miles through snow, up steep, root-filled switchbacks with thousands of feet of elevation gain, Courtney Dauwalter entered what she calls her pain cave. For the next 40 miles of the Western States 100-Mile Endurance Run through California’s Sierra Nevada, she imagined she was holding a chisel and chipping away at the furthest reaches of her pain, while staying focused on every step she took. By the time Dauwalter crossed the finish line in 15 hours, 29 minutes and 33 seconds, she had obliterated the women’s course record by more than an hour and had run the 23rd-fastest time, by anyone, in the race’s 45-year history.

To put Dauwalter’s time in perspective, it would have won the men’s division of Western States — arguably the most competitive 100-mile race in the world — every year from 1978 through 2009. Scott Jurek won Western States seven times (most recently in 2005) but never once ran as fast as Dauwalter did this year. She beat a 1994 Western State record set by Ann Trason, who won the race 14 times, by more than two hours.

Dauwalter is one of the most colorful characters in ultrarunning. She is known for her love of candy, nachos and beer, as well as her loose shorts and her vivid on-course hallucinations, which are illustrated on hats and T-shirts. In the past 10 years, she has won more than 50 races of 30 miles or longer. In 2017, she won a 240-mile race in Moab, Utah, by 10 hours. In winning Big Dog’s Backyard Ultra in 2020, she ran 283 miles and hallucinated that Mickey Mouse was standing on a circus stage handing out T-shirts to a crowd.

Now she is trying to do something even the most accomplished ultrarunners would consider extraordinary: win three highly competitive 100-mile races in a single summer. Twenty days after her performance at Western States, she won the grueling Hardrock 100 in Silverton, Colo., breaking her own record by 20 minutes and placing fourth overall. This weekend, seven weeks after winning Hardrock, she will toe the line at the Ultra Trail du Mont-Blanc, a brutally steep, 106-mile race in Chamonix, France, with terrain more suited to billy goats than humans. She has won the race twice and currently holds the women’s record.

“In general, I am pretty tired,” said Dauwalter, whose mottos when things get tough in a race are “This is fine” and “Be brave and believe.” She said running all three races was not the plan at first, but that she just had to try it.

“I am so curious what will happen and excited to test myself,” she said.

Lanky and blond, with a deep tan, expressive blue eyes and permanent laugh lines, Dauwalter, 38, believes one of the greatest evolutions in her running career has been her embrace of the “pain cave.” Initially, she thought of it as the place where she could no longer bear the suffering and would have to stop running. Indeed, she quit the first 100-mile race she attempted in 2012 because she was overwhelmed by pain. But as she ran more races, she started to understand that she could work through it. She said she envisioned herself in a hard hat, wielding a chisel and “going to town, trying to make it a dust pile while I am in there.”

She continued: “It feels like this is a special opportunity every time it arrives because we can’t summon it whenever we want. We have to be doing something hard, push ourselves, and then maybe we will get the chance to go in. And if we do, we should celebrate that we get to be there.”

Sitting on a deck that overlooks the Rockies at her home in Leadville, Colo., on a sunny, mid-August afternoon, Dauwalter sipped a fruity seltzer and pointed to two 14,000-foot mountains that she often runs to from her house. In a sport where most elite runners have a coach and map out their training schedules weeks in advance, Dauwalter trains herself and does not know how many miles she will run on any given day. Her mornings usually begin around 4 a.m. with a cup of coffee with vanilla crunch creamer. She responds to emails, then does about 40 minutes of strength training. By 7 a.m., she hits the trail and runs for an hour to five hours. She often adds a bike ride and a second run with her husband, Kevin Schmidt.

“I try and go into every week really open to whatever happens so that I will actually tune into my body and listen to it,” said Dauwalter, who wears a running watch but does not post her workouts on popular running apps like Strava, as many ultrarunners do. “If I go into a week thinking it is going to be a really big mileage week or I have all these grand ideas about it, then I find it harder to listen to my body and actually respond to what it is telling me.” Her big mileage weeks are often 140 miles.

Schmidt, a software engineer who said he didn’t know about ultramarathons until he met Dauwalter over a decade ago, tracks the possible mile splits she could have and meticulously plans the support stations along the course. Though Schmidt sets time goals, the couple does not focus on them or get too confident about a race until Dauwalter is at the finish line. In 2019, she was leading Western States, but had to drop out at mile 80 because of a leg injury. In 2021, her stomach issues were so severe at Hardrock that she couldn’t go on. Even when all goes as planned, random events can intervene, like when Dauwalter had to go off course to avoid a moose or lost her vision when her corneas swelled from the dust on the trail.

The pair said that nutrition is now a big part of their plan. A friend who works as a dietitian said Dauwalter had stomach problems in races because she was not getting enough calories. Dauwalter now picks up a plastic bag at each support station filled with an assortment of gels and energy waffles and carries water and a sports drink. Her job is to hand back a bag with empty wrappers.

Schmidt believes Dauwalter’s supportive family and her athletic background in her home state of Minnesota helped her learn to be aware of what she was feeling. She ran cross-country in high school and was a state champion Nordic skier, which earned her a skiing scholarship to the University of Denver.

“She had fantastic parents who raised her really well, encouraged her to be competitive and didn’t put restrictions on her, so she never felt like she couldn’t compete against her brothers,” Schmidt said. “And she had really great coaches who taught her how to be in tune with her body, which I think has helped her have this very unstructured training format that works for her.”

Meghan Hicks, the editor in chief of iRunFar, an ultrarunning website, said many runners unintentionally set limitations on themselves by focusing on a course record and the splits it will take to beat it.

“Courtney does not work that way,” she said. “She goes and runs by the way she is feeling.”

Hicks said Dauwalter has “a wide-open approach that you don’t see a lot of runners doing and I think that is perhaps part of her key to success.”

Dauwalter’s performances have led some to wonder whether women will become faster than men as distances get longer. Dr. Sandra Hunter, the director for the Athletic and Human Performance Research Center at Marquette University, said they will not. Men’s physiological and anatomical advantages, including less body fat, greater hemoglobin and higher oxygen uptake, mean that they will always be faster overall, she said.

For example, Jim Walmsley, who holds the men’s record for Western States with a time that is about 9 percent faster than Dauwalter’s. According to an article in Sports Medicine, in major ultra trail races where the best men and women are present, this number rarely dips below 8 percent. That was the difference between Dauwalter’s time and the fastest men’s time at Ultra Trail du Mont-Blanc in 2021. The gap between the best male and female performances for running events from sprints to marathons usually hovers around 10 to 12 percent.

“There is a fundamental sex difference between males and females that won’t go away,” Hunter said. But Hicks said women have reached a place in ultrarunning where they need not be compared to men because their performances are valid without that comparison — a view widely held by women in the sport.

Hunter said Dauwalter’s running economy, which is measured by the oxygen consumption of a runner at a set speed and often improves as runners get older, may be superior to most other participants in the sport. While there has been a boom of women ultramarathoners, there are still far fewer women than men in ultra running, and they usually run shorter distances like the 50K. Hunter said that Dauwalter’s stellar performance shows that there is still a great deal of room for women to evolve.

Dauwalter, who is known for being generous with her time and cheering on the people around her, continues to elevate others in the sport, especially women, Hicks said. In 2020, when Hicks set the fastest known supported women’s time in a roughly 90-mile challenge called Nolan’s 14, which involves hiking and running 14 14,000-foot mountains, Dauwalter paced her through the night, telling jokes and stories to make the time pass. Around midnight, she asked Hicks if she wanted a bite of pizza and pulled out a slice wrapped in tinfoil from her pack.

“Who does that?” Hicks asked. “Maybe your husband or your best friend? But who in the top of the sport is doing that?”

Dauwalter’s approach to the business of running reflects her desire to lift others in the sport. She used her sponsorship with Salomon to influence a new line of women’s running shorts that are longer and looser than most shorts on the market. Dauwalter hopes that the shorts will give women another option to be comfortable and that maybe “the length is the thing that makes someone get out on the trail and try.”

She also wants to inject some humor into what can be an intense pursuit. Recently, Tailwind Nutrition debuted a “Make New Friends” line of T-shirts and hats featuring images that Dauwalter has seen in hallucinations on the trail: a giant cowboy, puppets on a swing set, a giraffe.

John Medinger, the former publisher of UltraRunning Magazine, has been at every Western States since 1983 and has collected statistics on the race for over four decades. Dauwalter’s performance can’t be quantified, he said. No runner has posted times like hers in such a wide range of races — fast ones, steep ones, extraordinarily long ones and races of attrition in which the last person standing wins.

“There are courses for horses and horses for courses, but I’m not sure there’s a course that isn’t a good one for Courtney,” he said.