WOULD YOU EVER CONSIDER CLONING YOUR HORSE?

Picture this, you see your dream horse at an event and think ‘wow, I wish I could buy him’. Unfortunately, he is not on the market, but what if you propositioned for a tissue sample?

You can be forgiven for not knowing how popular cloning is becoming in the equine industry, with the first equids only successfully cloned 20 years ago. In this blog we give you the key facts in equine cloning - what do we know about it, why do it, is it ethical, and what does it cost?

What is cloning, and why do we need it?

Cloning produces an almost identical replica of another horse, and takes a DNA sample from a donor horse to then transfer into a recipient egg (that has had the DNA removed). This egg is then placed into the mare, and carried through to term.

The immediate benefits of cloning is that we now have the opportunity to conserve endangered species. Cloning is also revolutionary for breeding, for a few different reasons. 

Imagine the horse at an event that you wanted to buy earlier. When researching, you determined that they never bred any offspring and is now a gelding, and whilst you liked his dam and sire, he was the one. Cloning is unique in this scenario, as it provides the opportunity to not only clone an almost exact replica of the horse you have fallen in love with, but you can then also keep the clone entire and use them to further breed. 

Food for thought | Whilst it is incredible to be able to access a top performer's genetic banks, it is important to consider if cloning the same horse over and over for breeding will create what is referred to as a ‘bottleneck’ effect. That is, will we have enough dissimilar lines down the track to breed from if we keep cloning the same horse? If the clone was created purely for the outcome of winning, the sport has showed it’s continued breeding and quality improvements and there is nothing to suggest the clone would be as competitive when they matured, as the original was 8 years earlier. 

Do clones have a competitive advantage?

You may have seen me make the point earlier that clones are only partly identical to the donor horse, and as it stands currently, there is no research to suggest clones have a competitive advantage. It is important to note that clones are only 98% similar to the donor horse, and for those interested in learning more, it is mainly due to numerous epigenetic, mitochondrial and environmental differences, all which can be found in research. As riders, we also know that the way we train a horse has a major effect on how they perform. Not only does the training and conditioning a horse has effect their results at a top level, but there is research in heritabilities (how genes account for differences in traits) which shows correlations between the rider and results.

In competition terms, whilst we could clone a Valegro relatively easily, he is not guaranteed to be the same height, or perform the same, or have the same white markings, or have the same success. If we put the cloned horse in Charlotte and Carl’s yard, well, maybe he may be a little more likely to follow the same path, although that 2% variation will always be there. 

Sporting Ethics

The ethics of cloning in sport has been at the forefront of the media for sometime, with FEI banning clones from competing early on. The basis of the ban was that cloning could suggest a competitive advantage, going against their goal of fair play. The ban was since reversed and clones are now allowed to compete, right through to the Olympics. The Jockey Club and The American Quarter Horse Association still do not allow clones to be registered. 

How much does it cost?

When cloning was first commercialised, it was quite expensive. Now, services are offered for $35k +GST in Australia, which is significantly more affordable.

Welfare concerns

If you know anything about cloning from hearing of ‘Dolly’ the sheep, you’d probably assume that equine clones will age prematurely. Dolly’s cells were examined after she passed and the researchers found that her telomeres were shorter than normal for her age, causing the media to assume she died prematurely. We know she passed at 6 years of age, but not from premature ageing, and instead a viral lung tumour like many others in her flock. 

So, what welfare concerns are we actually looking at in the equine cloning space? I am going to reference some research in this space, keeping in mind that the process is continually developing and these concerns are consistently being reevaluated (published research will usually be slower to become available).

Equine cloning has shown to have a high percentage of placental abnormalities during pregnancy (Houdebine et al. 2008), with a study conducted by Johnson et al (2010) showing up to 50% of live-born cloned foals displayed some form of foetal pathology. In addition, research into the placental development of surrogate mares showed that the placental walls housing aborted clones had increased thickness, correlated to some levels of foetal stress (Vanderwall et al., 2006, Pozor, 2015, 2016). There is also a high number of neonatal abnormalities in cloned foals. The abnormalities mentioned above are quite significant in comparison to other assisted reproductive technique, although contemporary research has seen new modern techniques improve the success of live foal production, and reduce some abnormalities. 

Low success rates & ethics

Current research shows that three to four pregnancies are required to produce one live cloned foal, which is a significantly higher than normal wastage rate when compared to other assisted equine reproductive techniques (ARTs) (Campbell, 2018, Gambini et al., 2017). While very early embryonic loss is not considered as the loss of a live animal (as it is with humans), there are varying perceptions on the ethics of this loss, and it is up to personal standpoint as to your views. 

Are there any famous horses that have been cloned? 

There are actually quite a few famous cloned horses now under saddle or breeding. The most notable is probably the top eventing stallion Chilli Morning, who passed away in 2020, who has 3 clones on the ground who will be used for breeding, with Quattro with Gemma Tattersall for training. The two time silver medal winning showjumper Gem Twist also has two clones on the ground. 

So, knowing all of the above, would you clone your horse?

 

Some references for further reading:

Campbell, M.L.H. and Sand e, P., 2015. Welfare in horse breeding. Veterinary

Record, 176(17), pp.436-440.

Campbell, M.L.H., 2018. Is cloning horses ethical?. Equine veterinary education, 30(5), pp.268-273.

Hinrichs, K., 2006. A review of cloning in the horse. Reproduction, 52, pp.398-401.

Hinrichs, K., Choi, Y.H., Varner, D.D. and Hartman, D.L., 2007. 

Production of cloned horse foals using roscovitine-treated donor cells and activation with sperm extract and/orionomycin. Reproduction, 134(2), pp.319-325.

Houdebine, L.M., Dinny s, A., B n ti, D., Kleiner, J. and Carlander, D., 2008. Animal cloning for food: epigenetics, health, welfare and food safety aspects. Trends in Food Science & Technology, 19, pp.S88-S95.

Pozor, M.A., Sheppard, B., Hinrichs, K., Kelleman, A.A., Macpherson, M.L., Runcan, E., Choi, Y.H., Diaw, M. and Mathews, P.M., 2016. Placental abnormalities in equine pregnancies generated by SCNT from one donor horse. Theriogenology, 86(6), pp.1573-1582.

Vanderwall, D.K., Woods, G.L., Aston, K.I., Bunch, T.D., Li, G., Meerdo, L.N. and White, K.L., 2005. Cloned horse pregnancies produced using adult cumulus cells. Reproduction, Fertility and Development, 16(7), pp.675-679.

Vanderwall, D.K., Woods, G.L., Sellon, D.C., Tester, D.F., Schlafer, D.H. and White, K.L., 2004. Present status of equine cloning and clinical characterization of embryonic, fetal, and neonatal development of three cloned mules. Journal of the American Veterinary Medical Association, 225(11), pp.1694-1699.