With science and technologies advancing at such a rapid rate, it is important that the horse industry remains aware of the repercussions, real and potential, of genetically modifying horses.

Taken to an extreme, genetic engineering can be used to alter the appearance and athletic performance of horses, and create super athletes defined solely by the quality of their genetic material.

And in the recently released report Ethical Reflections on the Dignity and Welfare of Horses and other Equids, the Swiss Horse Industry Council and Administration (COFiCHEV) raised concerns over breeding for traits that may cause disease, as well as the use of cloning and gene doping in the equine industry.

Genetic testing for disease

Not knowing which horses are carriers of known heritable diseases dramatically increases the risk of breeding an unhealthy foal. The World Arabian Horse Organization (WAHO), American Quarter Horse Assotiation (AQHA) and American Paint Horse Association (APHA) all recommend testing registered horses to prevent genetic diseases from being passed down to foals, but in any closed stud book, perhaps it should be compulsory.

This is because in a closed stud book, every generation loses genetic diversity, and with it, the deleterious mutations (that is those carrying disease) increase.

The Swiss council warns against the breeding for heritable colour traits known to be associated with genetic diseases. Stating that these “genetic faults have a negative impact on the reputation of a breed and the commercial value of stallions and broodmares.”

Genetic testing is an excellent way of identifying alleles responsible for heritable disease and accurately predicting whether a horse used for breeding will produce affected foals.

A horse who turns out to be a carrier can still be used for breeding with an unaffected horse. Still, breeders must realise that this practice will result in the gene being maintained within the breeding population, potentially causing diseased foals to be born down the line.

(Allele, biology definition: variant of a gene controlling the same trait and occupying a specific region on a chromosome – called the locus.)

Reproductive cloning

Reproductive cloning is a controversial breeding technique that reproduces an animal with the same nuclear DNA as another living (or previously existing) animal. Since the birth of Dolly, the first fully cloned sheep, in 1996, cloning technology has been growing in popularity with horse owners, despite the high cost.

The report highlights concern about the welfare of recipient mares gestating and giving birth to implanted cloned foals. The delicate process of preparing and implanting a cloned embryo often fails and can cause considerable emotional stress and pain to the mare. Cloned foals have a higher infant mortality rate than naturally conceived foals, and often, embryos that gestate to term are stillborn or pass away in the days following birth.

Transparency inconsistencies in cloning practices are also mentioned, with the council noting that some breeders have purposefully kept information about their cloning operations concealed from others, undermining confidence in the process. There is also a need to classify better the difference between cloned horses derived from an original horse and clones of clones.

Cloned polo pony foals

Rules differ considerably between sports and breed associations regarding cloned horses. The breeding technique is not allowed by the thoroughbred, Arabian, and standardbred studbooks nor the American Quarter Horse Association; however, cloned horses are well represented in sports like show jumping, endurance, and polo.

Organisations that register clones include most Warmblood stud books and the World Breeding Federation for Sport Horses. The FEI Olympic governing body allows cloned horses to participate in FEI competitions.

Cloning is a viable technique for safeguarding genetic resources

Endangered breeds, if not protected, could eventually become extinct. Many populations are rapidly losing genetic diversity; cloning genetically valuable horses (both living and deceased) could serve to broaden the gene pool and save these endangered breeds from extinction.

Equids that have been lost include the Tarpan, the Quagga, and the Syrian Wild Ass, all irreversible tragedies that might have found a solution in genetic cloning, had samples of viable DNA been collected long ago.

Cloning technology has, however, been used successfully to renew endangered horses like the Przewalski’s horse. In the USA, an adult cow gave birth to a Guar, an endangered species of ox from South America, and in 2003, researchers used cloning to bring back an extinct Pyrenean ibex, using a modern goat as a surrogate mother.

Using stored frozen DNA, genetic scientists can potentially bring back lines that have died out. Horses of the past and present can be cloned for use in breeding programs, enabling otherwise “lost” genes to be reintroduced to gene pools lacking in diversity.

In Switzerland, cloning is still seen as an animal experiment subject to authorisation, and the COFICHEV council found that while the process may be a viable technique for safeguarding genetic resources, there is not yet an overriding argument that can justify cloning as a method of breeding horses.

Gene editing: doping of the future

Gene doping can take a multitude of forms, including gene transfer, gene silencing and gene editing and includes processes or treatments involving the insertion, deletion and/or replacement of pieces of DNA in the genome of a horse.

An example of gene editing is when a scientist replaces the DNA sequence of a horse and knocks out the Myostatin gene (MSTN) to enhance muscle growth and short-term speed.

Candidate genes for this technology include those that affect oxygen regulation, increased blood flow, metabolism and genes that can help a horse overcome pain.

Progress in this field has happened so fast that the dialogue around policy, regulation, and benefits is struggling to catch up. Worryingly, some scientists have already shown their desire to ‘push ethical boundaries’; the most famous is the Chinese scientist He Jiankui, who was jailed for genetically modifying two human babies.

The report warns that genetic engineering may result in ‘stronger, faster and more resilient (equine) athletes who could be pushed beyond their usual limits.’ and that tampering with a horse’s genes to gain a completive edge ‘threatens the integrity of equine athletes, respect for rules and regulations in competitions, and the sustainability of horse breeding.’

The council finds ‘from an ethical point of view, the use of techniques that transform the genetic heritage of living beings is a very serious blow to the inherent worth of those living beings, whether animal or human.’

To prevent unregulated use of genetic engineering techniques, the council advocates introducing a ban on molecular genetic techniques in animals in the AniPO and for sports federations, the implementation of a decentralised blockchain-based application to enhance the general public’s image of equestrian sports.

While genetic technologies can be used to improve equine health and genetic diversity in rare breeds, the question is, can it be done responsibly?  New technologies designed to help have been abused and manipulated for human benefit through history.

Horses should never be regarded as a product that can be altered and played with for our own benefit or desires. There’s no need to rush the future. We are already here.