During this summer's World Cup, an intriguing story was almost lost amid the carnival. As many as eight Tunisian football players tested positive for Clenbuterol, a drug banned in human sports and regulated in horse racing due to its anabolic properties.The players were stationed in the Mexican city of Monterrey, and the positives have been largely linked in the news to the consumption of drug contaminated meat. Indeed, the UK's Times reported that the “trace” levels were below a threshold “introduced owing to the sheer number of cases involving contaminated meat–in particular in Mexico.”The Federation Internationale de Football Association (FIFA) did not respond to multiple requests for comment into what kind of investigation it had conducted into the incident.Though it's illegal to do so, Mexican ranchers have historically used Clenbuterol to help fatten their cattle. Indeed, World Anti-Doping Agency spokesperson James Fitzgerald shared with the TDN a factsheet detailing how, outside of clenbuterol, the synthetic hormones ractopamine, zeranol and zilpaterol are also used as a “livestock growth promoter.”WADA's factsheet raises two possible scenarios from the detection of low concentrations of these drugs in human athletes. One is that they reflect the “tail-end of excretion of a steroid used for doping purposes.” The other is that they are due “to the consumption of contaminated meat.”If that latter, however, what meat exactly? Research into the export of horses from the U.S. to Mexico for human consumption raises the possibility the meat the Tunisian players allegedly ate was horse rather than cattle meat.And if that's the case, then this issue once again raises major ethical questions over the export of horses administered Clenbuterol and an array of other commonly used drugs never intended to enter the food chain, due to their potential to harm humans.“In the U.S., horses aren't raised for human consumption, so, they're getting all kinds of these drugs, both legal and illegal,” said Chris Heyde, who runs the governmental affairs firm Blue Marble Strategy, and who has long worked to push through the SAFE Act, which would ban the transportation of U.S. horses for slaughter for human consumption.“These drugs are not supposed to be going into the food chain,” Heyde added. “And the thing is, nobody's really looking for it either.”Contaminated Horse MeatWhile the management of food animals is strictly regulated in the U.S. to ensure banned drugs don't enter the food chain, “the U.S. Department of Agriculture does not have a system to remove horses administered banned substances from the slaughter pipeline,” notes a paper published by the AVMA.Virtually all slaughter-bound American horses sent to Mexico and Canada are eaten by humans, their meat either consumed locally or shipped globally.Due to food safety concerns, the European Union banned the import of horse meat from Mexico over 10 years ago, while the issue of drug-tainted horse meat sold as beef in Mexico has been on the radar of researchers for a while.Published in 2019, a Clenbuterol-focused story in Science Direct took meat samples from a range of Mexican cities and sources, including supermarkets, street vendors and butcher's shops. They found that 10% of the 433 samples purporting to be beef tested positive for horse meat.The researchers looked at both raw and cooked meats.“Clenbuterol was observed in all of the raw meat samples containing horse meat,” the study notes.Eating Clenbuterol-contaminated meat can cause an array of health effects including palpitations, myalgia, vomiting, even atrial fibrillation. As such, the drug is deemed a consumer health risk.Heat stable, Clenbuterol is not eliminated from meat when cooked, even at high temperatures. And it can remain in a horse's system for at least a year after administration.Similar research on other drugs has yielded similar results to the Mexican study.The same AVMA paper also examined bute, a cheap and widely available nonsteroidal anti-inflammatory used ubiquitously within horse racing circles.The Food and Drug Administration (FDA) bans the administration of bute in food animals. Not so horses, as the horse, so says the FDA, is a companion animal.“Phenylbutazone is the drug that prompted the concern in Canada as it can cause fatal blood diseases in people,” wrote Tom Lenz, a veterinarian and former president of the American Association of Equine Practitioners (AAEP).“However, it has a very short half-life and is metabolized by the horse very quickly and therefore, no longer a risk to people consuming horse meat,” he wrote, describing the human health threats from drug-tainted horse meat as “a bit overblown.”The study in the AVMA, however, argues the question of how long bute remains in a horse's flesh is more complicated, impacted by a variety of factors, including the age of the horse, the frequency of bute administration, the dose, and just how chronic the health issues are for which the horse has been receiving the drug.Canada requires U.S. sourced horses slated for consumption in the EU to be held at the feedlot for a minimum six months. Every horse that comes across the Canadian border must also come with an owner declaration that the horse has not received any prohibited drugs over the past six months. There remain questions marks about the efficacy of these restrictions.The study in the AVMA notes that the Canadian Food Inspection Agency (CFIA) tests less than 1% of horse carcasses for the presence of drugs. Belgian regulators detected a metabolite of bute in over 7,000 kgs of horsemeat from Canada in 2017.Two years later, EU regulators classified the risk of Canadian horsemeat containing the drug as “serious.”There's a very good reason bute shouldn't enter the food chain. Back in the 1950s, it was introduced into the market to treat rheumatoid arthritis and gout. But within a matter of years, the drug had been linked to life-threatening blood disorders like aplastic anemia and agranulocytosis, as well as deaths at even at therapeutic doses.By the mid-1980s, bute was banned for use in humans, the health risks just too great. It now comes with a black-box warning about these potential harms to humans.In his email, Lenz wrote that “very few horses” go directly from competition, the ranch or riding stable to the slaughter pipeline, and are usually “shopped around to potential buyers for some time before being shipped to Canada as they are worth a lot more money sold as a riding horse or companion than as a meat animal.”Looking at the entire U.S. horse population, “very few receive drugs” other than dewormers, Lenz wrote. “Horses in competition may be treated for a variety of problems, but the drugs and the time frame in which they can be given is strictly regulated by the competitive authority such as the American Quarter Horse Association, U.S. Equestrian Federation or racing authorities,” he added.“Most of the horses going to Canada or Mexico are lower-quality horses, horses that have never been trained, old, unusable horses or horses with behavioral problems. They are not the horses that are being shown, raced or treated with drugs,” Lenz wrote.But the racetrack to slaughter pipeline (even within a window of days or weeks) has indeed long been a major black mark against the sport.While there's no accurate number of ex-racehorses that end up on foreign dinner plates annually (there's no tracking of horses at the border by breed), those who monitor this issue estimate between 6% and 10% of horses exported are Thoroughbreds. Last year, around 25,000 U.S. horses went for slaughter.“If the United States is unable to put in place a regulatory program to remove horses administered banned drugs as exists for all food-producing animals, the exportation of American horses across both borders for the sole purpose of slaughter for human consumption must end,” the authors of the AVMA-published paper argue.SAFE ActAt the end of May, the House Transportation and Infrastructure Committee passed the BUILD America 250 Act which included a ban on transporting horses for slaughter. The broader BUILD America bill is now awaiting a vote in the House.While versions of the SAFE Act have been knocking around for years, “this would be the second-closest this has gotten to passing,” said Pat Cummings, who, under the auspices of his and Mike Repole's National Thoroughbred Alliance, has been working to push through this legislation.SAFE Act language last passed the House in 2021. But then the Senate took up the bill, and the one that eventually passed excluded any SAFE Act language.While this current version of the SAFE Act has gotten further than many prior versions, it faces a Capitol Hill in many ways rusted shut legislatively thanks to partisan gridlock.Pat Cummings | HBPAThen there's opposition from cash-rich lobbyists, including the influential National Cattlemen's Beef Association (NCBA) which recently released an email to members and other political operatives describing the bill as a “Trojan Horse” led by animal activists with one clear goal.“Activists want to eliminate transport of cattle, pigs, and sheep and destabilize the entire food chain,” the NCBA claims.“The amendment has nothing to do with transportation and creates a burdensome regulatory process that leads to more abandonment, more neglect, and more starvation across all livestock sectors. If enacted, it will set an incredibly dangerous precedent for prohibiting transportation of all livestock, including cattle, that are crucial to American food security,” the NCBA adds.The NCBA did not respond to requests for comment for this story.Proponents of the SAFE Act argue they aren't swayed by the argument it would lead to a mass dumping of unwanted horses.Prior research by critics of horse slaughter found no connection between the end of the practice in the U.S. and an uptick in horse neglect case numbers, which, the research suggested, instead were driven by a stagnant economy.According to the American Horse Council, there are more than 6.6 million horses in America. Last year, an estimated 25,000 American horses were shipped abroad for slaughter.“In 2016, 10 years ago, the total number of horses sent to slaughter in Mexico was 79,214. So, more than 57,000 fewer horses were sent to Mexico last year than 10 years earlier. And we have not seen an uptick in the number of neglect cases,” said Cummings.There might, however, be another new wrinkle in the effort to stop American horses ending up on foreign dinner plates, and that's the screwworm infestation that has hit Mexico, placing an additional demand for horse meat.According to reports, the number of horses slaughtered in Mexico in 2025 was up about 25% from the year prior.“Through all of our different research, the number one reason we believe more horses were slaughtered in 2025 than 2024 was constraints on the beef supply in Mexico,” said Cummings.“Given the clear research that exists recognizing the degree to which horse DNA has been found spread across Mexican beef, dating to 2019,” he added, “it reasons that with substantial constraints on Mexico's domestic beef supply and with rising costs on legitimately sourced beef, the underregulated market is very likely filling orders with meat sourced via horse slaughter.”The post Horse Slaughter, Clenbuterol, and the World Cup appeared first on TDN | Thoroughbred Daily News | Horse Racing News, Results and Video | Thoroughbred Breeding and Auctions.