The work being done to monitor and detect gene doping practices and understanding the future perspectives in breeding
The pursuit of genetic perfection no longer ends with traditional selection. Alongside meticulously planned breeding programs and increasingly sophisticated genomic profiling, a new and controversial possibility is quietly gaining ground - gene doping. The idea of altering a thoroughbred’s gene expression to enhance muscle power, endurance, or cellular recovery is both compelling and profoundly unsettling.
In experimental research, these tools are already being tested using animal models and although no official cases have been reported in racing so far, the specter of their potential use is growing increasingly real. The discourse around gene doping and gene therapy more broadly, is emerging with greater urgency, raising complex ethical, technical, and regulatory questions.
This is an extremely dangerous development, not only because it threatens the integrity of competition, but also due to the unknown risks it poses to the animals themselves, who may be subjected to genetic manipulation without the capacity to understand or consent. Both the World Anti-Doping Agency (WADA) and the International Federation of Horseracing Authorities (IFHA) have taken a clear stance against such practices, prohibiting their use in both human and equine athletes.
Despite these regulatory safeguards, the rapid pace of genetic science is testing the limits of current frameworks. Advances in biotechnology are no longer confined to the laboratory or speculative discourse they are beginning to manifest in the real world. While equestrian regulators have outlined strict prohibitions, enforcement is inherently reactive, often lagging behind innovation. The gap between what is technically possible and what is legally permitted is widening, and within that space, experimental applications of gene editing are quietly advancing. It is in this grey zone, between regulation and research, that the first real-world example of genetically edited equine athletes has emerged.
This shift from theory to application became strikingly evident in October–November 2024, when Argentina’s biotech firm Kheiron Biotech announced the birth of five genetically edited polo foals, marking the world's first CRISPR‑Cas9–engineered equine athletes.
These horses were derived from mesenchymal stem cells of Polo Pureza, a champion Argentine polo mare celebrated in the breeders’ Hall of Fame. Rather than cloning, scientists used CRISPR‑Cas9, a highly precise genome-editing tool, acting like molecular scissors to modify specific DNA segments. The primary target was the myostatin (MSTN) gene, which restricts muscle growth by silencing or altering this gene. The resulting foals were designed to possess enhanced muscle mass and explosive speed, while preserving the mare’s natural agility and temperament.
The editing process involved removing an oocyte’s nucleus, replacing it with DNA from Polo Pureza’s edited stem cells, and implanting the embryos into surrogate mares; five live foals were born from eight pregnancies.
In the context of the horse racing industry, where the value of a Thoroughbred can hinge on milliseconds of performance and the ability to sustain speed over distance, gene editing presents an especially tempting field.
Can we imagine this scenario extending into the racing world?
Scientifically, the answer is yes. The same techniques used to enhance athletic potential in polo ponies could, in principle, be applied to racehorses. Several genetic traits directly influence race performance and could be enhanced through precise gene editing. The range of traits that could be enhanced is both broad and strategically targeted. The ultimate goal would be to produce a horse that runs faster, resists fatigue better, recovers more quickly, and possibly even suffers fewer injuries, all thanks to targeted genetic interventions.
One of the primary areas where gene editing could intervene is muscle development. Racehorses rely on explosive power and speed, and one of the key genes responsible for regulating muscle growth is myostatin (MSTN).
This gene acts like a natural limiter, preventing muscles from growing excessively. By suppressing or modifying MSTN, it’s possible to significantly increase the mass and strength of skeletal muscles, giving horses more power during acceleration and allowing them to maintain higher speeds.
Enhancing muscle development could be especially valuable for short-distance (sprint) races, where raw power is a major performance factor. Alongside MSTN, scientists may also target follistatin, a glycoprotein that naturally inhibits myostatin and encourages muscle growth. Its manipulation, already studied in other species, could serve as an indirect yet powerful enhancer of muscle development in horses.
Another key aspect involves muscle endurance and recovery, where hormones like Insulin-like Growth Factor-1 (IGF-1) and growth hormone (GH) play essential roles. IGF-1 stimulates protein synthesis and helps in repairing tissue damage after intense effort.
Gene therapy involving IGF-1 has shown increased muscle mass in animal studies, even without training. When combined with exercise, its effects are amplified, and it may also reduce muscle loss during periods of rest (highly relevant in racing horses recovering from injury or off-season periods).
Performance in longer races, however, is not just about power, it’s about how efficiently a horse uses oxygen. Here, oxygen transport genes like erythropoietin (EPO) and HIF-1 become highly relevant. By increasing red blood cell production, these genes allow muscles to receive more oxygen during effort, delaying fatigue and improving aerobic endurance. In practice, a horse with genetically enhanced EPO expression could maintain high levels of exertion for longer without performance dropping off. In addition, HIF-1 also activates other processes, such as the formation of new blood vessels (angiogenesis) and improved mitochondrial function, both of which contribute to athletic stamina.
There is also the possibility of influencing muscle contraction efficiency through genes like ACTN3, which is associated with fast-twitch muscle fibers, those responsible for rapid, explosive movements. Variations in this gene may help differentiate a horse better suited to sprints versus long-distance racing.
Beyond functional performance, gene editing also opens the door to phenotype modification, adjusting physical traits that contribute indirectly to racing ability. This includes aspects like limb length, back structure, stride angle, body mass distribution, and joint strength. Studies have identified quantitative trait loci (QTLs) and genes like TBX15 that influence skeletal development and muscle fiber differentiation.
By acting on these, one could refine the physical ideal standard of a horse to better match the ideal conformation for speed and biomechanics. This would mark a radical shift from traditional breeding, where physical traits emerge through generations of selection, to a scenario where conformation is engineered at the embryonic stage.
In essence, the application of gene editing in horse racing presents the theoretical possibility of designing equine athletes tailored not only for general fitness, but for specific racing distances, styles, and even track conditions. A genetically customised thoroughbred could, in theory, be built for explosive sprints, long-distance endurance, or optimal biomechanics on certain surfaces.
“Does the end justify the means?”
This timeless question, posed by Machiavelli centuries ago, feels strikingly relevant in today’s ethical debate over gene editing in sport horses. The growing scientific evidence that gene editing in horses is not only possible but increasingly feasible brings to the forefront a complex and deeply important moral dilemma. Just because we can manipulate the genome of a future equine athlete, should we?
At the heart of the discussion lies the fundamental value of fair play, a core principle that defines the legitimacy of competitive sport. If one horse is genetically enhanced before birth while others are bred through traditional means, can they still compete on equal terms? Gene editing, by its very nature, introduces an artificial advantage, one that is not earned through training, nutrition, or breeding judgment, but through direct technological intervention at the biological level.
Such practices risk turning the racecourse into a competition not of horses, but of laboratories and geneticists. The fairness of the sport would be compromised, not only for competitors but for owners, breeders, and spectators who trust in the authenticity of the contest. Moreover, equine athletes cannot give consent to be genetically modified. Altering their genome for human-defined goals raises profound questions about animal welfare, autonomy, and dignity. Is it ethical to “design” an animal for performance, knowing that such manipulation may also carry unknown health risks or reduce genetic diversity?
While innovation has always shaped sport, from training techniques to equipment, the line between enhancement and manipulation must be clearly drawn. Gene editing, when used for performance purposes, crosses that line. It challenges the spirit of horsemanship, the unpredictability of natural talent, and the integrity of racing itself. Ultimately, preserving fair play may mean accepting the biological limits of even the most elite Thoroughbreds and recognising that what makes sport meaningful is not control over the outcome, but the uncertainty of it.
Indeed, these ethical concerns have not gone unnoticed by the governing bodies of equine sport. Organisations such as the World Anti-Doping Agency (WADA), the International Federation of Horseracing Authorities (IFHA), and most notably the British Horseracing Authority (BHA) have already taken a firm and proactive stance against the use of gene editing for performance enhancement.
The BHA, in particular, is now leading the way globally in developing and implementing anti-gene doping protocols within its world-class equine anti-doping programme. In a decisive move to protect the integrity of British racing and the welfare of thoroughbred horses, the BHA has officially expanded its anti-doping operations to include routine testing for gene doping, both on raceday and out-of-competition.
This includes the detection of direct DNA manipulation via gene editing as well as gene transfer, where foreign genetic material is introduced into the horse’s cells to boost athletic traits or accelerate recovery.
Such practices are clearly prohibited under the Rules of Racing, and the BHA recognises gene doping as a serious and growing threat, not only to fair competition, but also to equine health and the future integrity of the breed.
To confront this emerging risk, the BHA has invested nearly £2 million in cutting-edge scientific research in collaboration with the LGC laboratory in Fordham, establishing a dedicated gene doping detection team as early as 2019.
In partnership with the Centre for Racehorse Studies, researchers at LGC have successfully developed analytical techniques capable of identifying evidence of gene doping, achieving UK Accreditation Service approval to perform this next generation of highly sensitive testing. This new gene doping detection framework is already active, forming part of a comprehensive testing programme that combines random sampling with intelligence-led investigations.
The goal is not only to ensure compliance with the Rules of Racing, but also to act as a powerful deterrent preserving the fairness of the sport and prioritising the welfare of the horse. With this initiative, the BHA is sending a clear message: that the use of genetic engineering to manipulate equine performance will not be tolerated, and that the tools now exist to detect and act upon it.
Gene-doping represents the current frontier of innovation and concern within the world of racing. While science continues to demonstrate the increasing feasibility of genetic intervention, both in theory and in practice, this progress brings with it a set of unresolved questions that extend beyond biology or regulation.
The potential to influence a horse’s genetic makeup with surgical precision is no longer a distant possibility, but a reality under active discussion. Yet, embracing such power uncritically could signal a shift in the very foundation of equestrian sport: from a celebration of natural ability, training, and partnership, to a controlled outcome engineered in a lab.
At its core, this conversation is not just about doping, it is about the boundaries between humans and nature, between technological capability and ethical restraint, and between competition and manipulation. The choices made now will shape not only the future of the sport, but also its meaning. As the line between what is possible and what is permissible becomes increasingly thin, the challenge will not only be to detect gene doping, but to decide, collectively, whether sport should allow itself to go down this path at all.