Is the equine science of embryo transfer ethical? The practice of equine embryo transfer is becoming more and more accessible to breeders as a way of obtaining offspring from mares who might be compromised through age, fertility problems or injury in their ability to produce a healthy foal, or from those who still have an active competition career and can’t afford the ‘time off’ for active pregnancy. It is also becoming an important ‘life raft’ in the preservation of rare breeds but is it playing God or employing good science?

With advanced assisted reproductive techniques (ART’s), it is now possible to produce a foal from the union of a deceased stallion and a top level competition mare who continues to compete throughout. Indeed, it is possible to produce several foals from this union in a single year!

Of course, these practices raise a number of moral and ethical questions, which must be closely scrutinised if we are to go forward with a clear conscience. We must consider the ethics and wellbeing of all involved, including both the donor and recipient mares, and the resulting offspring. But, does that consideration extend to the embryonic stage? Does the embryo itself deserve the same rights and ethical concern as the resulting horse that it will become?

In a recent feature, the Equine Veterinary Journal (EVJ) presented four papers looking at various aspects of embryo transfer. As an introduction, Madeleine Campbell, European Diplomate in both Equine Reproduction and Animal Welfare Science, Ethics and Law, presented a discussion of the ethical concerns that might arise concerning equine embryos (defined as being less than 42 days of gestational age).

The introduction explores the questions of whether we ought to be worried about the use of embryos in equine research and, in particular, the damage or destruction of them for research purposes, or during the embryo transfer process itself.

Campbell explains any damage to embryos which causes the future pain, suffering, stress or discomfort of the postnatal foal should be cause for ethical concerns on the grounds of welfare, but asks whether the damage or death of equine embryos in and of themselves should be a matter of ethical concern.

In the United Kingdom, legislation dictates that animals are only protected by regulations governing experimental design and clinical procedures in the third trimester of pregnancy onwards, with no provision for the younger neonate.

The notion of ‘embryo suffering’ is explored. Can embryos feel pain? To date, there is no suggestion, based on scientific evidence, that embryos are capable of suffering and, therefore, there is no evidence-based rationale to suggest a welfare concern about damage or death of embryos themselves, unless they are allowed to continue their development through to the third trimester.

But, is it morally right to use embryos experimentally; to use them in embryo transfer with variable success, or to ‘squeeze’ them – as the process is called – if there happens to be more than one occupying the same uterus?

If our moral concern is based on the animals’ ability to suffer, then clearly, there is no concern where embryos are concerned, right?

When we consider human embryos (with no evidence to suggest they can suffer or feel pain), which are still considered worthy of respect simply because they represent potential people, should we then consider equine embryos, with the same respect as potential horses? Should horses have the same moral rights as humans, including the right to life?

Campbell suggests, if we are comfortable with the notion of equine euthanasia, even for non-welfare-based reasons, and taking the life of a horse is morally acceptable, as long as it is done humanely,  then we should concede we do not believe horses have the same right to life as humans. And, with this argument in mind, it makes no sense to consider the rights of the embryo as any greater than the rights of the resulting horse that it might become. Campbell argues there is no coherent argument the treatment of embryos should be considered as an ethical dilemma.

What about all the positive outcomes from embryo transfer? The use of this improving technology in the preservation of rare breeds, such as the Suffolk Punch from the United Kingdom and the ancient Przewalski horses of Mongolia, is proving a valuable tool that might make all the difference in the survival efforts for these breeds, amongst others.

The Suffolk Punch is a much loved and iconic draft breed in the United Kingdom, which has difficulties with fertility, possibly due to closely connected bloodlines. Semen for artificial insemination (AI) is difficult to obtain and mares often have trouble maintaining a pregnancy once successfully inseminated. The situation for the critically endangered breed is so dire experts have recently predicted we have less than 10 years to act before the breed disappears entirely.

There remain just 80 viable breeding females in the United Kingdom, meaning the Suffolk Punch is now in the top three breeds of farm animals facing extinction. In a bid to save the iconic breed, genetic samples are being taken and stored cryogenically with the aim that future technologies will allow a resurrection from this material, should the current preservation activities in place prove unsuccessful in the long-term.

In the meantime, embryo transfer is providing a way to increase the number of pregnancies by using large draft breed surrogates to carry the valuable offspring to term. In Australia, between 2016 and 2017, five Suffolk Punch foals were born – four of which were embryo transfers. But, the process is expensive and prohibitively so in some cases. Fundraising by breed societies is helping to increase the viability of embryo transfers for some breeders, but the breed is still in grave danger of disappearing if assisted reproductive techniques are not more widely available.

In Mongolia, the battle to save the critically endangered Przewalski horse has been a long and arduous one. As the last remaining breed of truly wild horse, the issues surrounding their dwindling numbers include a diminishing habitat, as well as an ever decreasing gene pool. The Przewalski is one of the oldest surviving breeds of horse and is familiar as a breed depicted in cave paintings by our early ancestors. Due to habitat loss, and increasing difficulty of finding food and water, their numbers have been dwindling for many years.

Early attempts at capturing and breeding in captivity proved challenging, with many young horses not surviving the ordeal. The small numbers of stallions meant a very small gene pool from which to breed the captive animals. Genetic weaknesses ensued, hampering future efforts to increase numbers. The main purpose of the Species Survival Plan (SSP) is to maintain a healthy and genetically diverse wild population of horses. To this end, horses and genetic material are now transferred between zoos all over the world, to ensure as large a gene pool as possible.

Out of 80 zoos worldwide hosting the Przewalski horse, 20 to 30 will produce foals each year. Many horses will be successfully re-introduced to the wild, thus increasing the population and genetic diversity of the wild herds. Recently, embryo transfer has entered the toolbox, which breed conservationists have used to help maintain the breed. Nine pure Przewalski embryos were successfully transferred surgically and two non-surgically to domestic mares. Seven of the embryos became viable pregnancies and four foals were, ultimately, born.

Embryo transfer allows the combination of very specific genetics from the mare and stallion, and a far larger number of foals born to that coupling than would be possible naturally. The technology means far less chance of genetic disease, as well as overcoming the geographic limitations of breeding a certain mare with a certain stallion. The use of embryo transfer, along with other technologies, may just be the difference between survival and extinction for this important horse breed.

Whilst ‘messing with nature’ will always raise a healthy amount of debate, and questions of ethics and morality, if we can make a positive difference to the lives and, indeed, the very survival of horses by employing it in a thoughtful and clearly planned programme, then surely the ends must justify the means?

Whether we should be using the technology to breed the next fastest racehorse or the best eventer from a mare still competing actively, or whether fears of ‘designer foals’ with genetic traits picked from a list and meddled together in the laboratory are warranted, the technology as it stands today is not to be feared in and of itself.

So long as we continue to ask the pertinent questions, and be truthful about the potential risks and ethical considerations, can we agree the benefits outweigh the concerns with the technology we have available?

The Equine Veterinary Journal (EVJ) special focus section appeared in the May 2018 issue, including four research papers examining some of the latest methods, protocols and success factors involving embryo transfer.

The special focus is available free online here.

Read more about the equine science of embryo transfer here.