An Inside Look at Equine Cloning
By Margaret Evans
A recent poll on the Canadian Horse Journal website asked the question: Should equines be cloned?
Some 83 percent of respondents said no, not until more research has been done; 15 percent said maybe, in special situations with strict parameters; just two percent said yes, and that registration of clones should be allowed.
Once the darling concept of science fiction writers, cloning trotted onto the world stage on February 22, 1997 when it was announced that Dolly the sheep, a ewe cloned at the Roslin Institute in Midlothian, Scotland, had been born on July 5, 1996. Dolly was the first mammal to have been successfully cloned from an adult cell. She lived at the Institute until her death in 2003.
Dolly kicked the scientific barn doors down to open the way for all manner of cloned mammals. Along came “twins” of cats, rats, deer, cattle, fruit flies, rabbits, and others. Then, on May 4, 2003, the first equine and first mule, Idaho Gem, was born at the University of Idaho. He was quickly followed by two cloned “siblings,” Utah Pioneer born on June 9, and Idaho Star born on July 27.
Idaho Gem came along just a couple of weeks before the birth of the first cloned horse, Prometea, a Haflinger foal born May 28, 2003, at the Laboratory of Reproductive Technology, Cremona, Italy. The first cloned horse in North America, Paris Texas, was produced by Texas A&M University in 2005.
In 2006, the premier barrel racing gelding, Scamper, was cloned and his “twin” stallion became the first cloned horse to stand at stud in the US In 2010, a Criollo horse was born in Argentina, the first horse clone produced in South America.
But what really is cloning, and is the cloned horse literally identical to the original animal?
“We take advantage of two things,” explains Dr. Katrin Hinrichs, professor and Patsy Link Chair in mare reproductive studies at the College of Veterinary Medicine & Biomedical Sciences, Texas A&M University. “One, the nucleus of every cell in the body has the same DNA which codes for how to produce the entire animal. Two, the oocyte (egg) is ready to make an embryo, packed full of everything that will be needed for that embryo for the first three to four days of development. The basic procedure is just a variation on what happens normally at fertilization. Normally, the egg has half of a complement of DNA and the sperm enters the egg and brings in the other half of the needed DNA. Then, with a complete set of DNA, the egg starts to develop into an embryo. In cloning, we remove the DNA from the egg then introduce a cell [from the donor horse] that carries a full complement of DNA. Then we signal the egg to start to develop into an embryo.”
A cloned embryo that has developed to the stage at which it can be successfully transferred to the uterus of a recipient mare. It takes about seven to eight days of culture to get to this stage, and it typically has 100 to 500 cells at this stage. Photo courtesy Texas A&M University
Hinrichs explains that, while there are no changes to the genetics (DNA) of the cloned horse, the genes in the clone could be used differently – turned on more, or less, than they were in the original. Therefore, to a varying extent, the clone will differ somewhat from the original.
“Sometimes the placenta does not work as well as it should,” she adds, “and this can affect the health of the foal at birth, making it weak or having a large umbilical cord.”
As much as people might think that a cloned horse is a duplicate of the original, it does not necessarily follow that it can do what its original – often called its “twin” - can do. If the foal was weak at birth or if it was born with crooked legs (as may happen with any normal foal due to its position in the uterus or the pliability of membranes around it), the foal may not have the athletic qualities of the original horse. In addition, athletic ability is also a product of the animal’s environment, handling, management, and training.
Each horse has its own unique character, again shaped by its cumulative experiences, exposure, and handling. According to Hinrichs, there have been no studies to date on how similar the cloned horse is to its original twin. A misconception, she says, is that cloning will produce the same animal with the same memories and experiences. That simply isn’t possible. Cloning produces a genetically identical twin but, like any set of twins, each will have their own memories and experiences.
So why clone?
“We have found that each of our clients often has a unique reason for their cloning interest,” says Blake Russell, president of ViaGen in Cedar Park, Texas. “We are producing similar numbers from each gender and still reproduce genetics from great, proven stallions. There is a compelling case for cloning the elite ones, whether they spent their life as a mare, a gelding, or a stallion.”
ViaGen is a division of Trans Ova Genetics and offers cloning services and state-of-the-art technology for all non-primate species. It has offered its equine cloning service for 13 years. During that time it has produced 200 foals and the company has licensees in both Brazil and Argentina who are producing cloned foals, some for the polo market.
The most frequent reason for cloning is to preserve the unique genetics of an elite equine athlete whether in show jumping, polo, or barrel racing. Many of these horses are either geldings or mares. While mares can be bred, geldings of course cannot. If these valuable animals are cloned, their twin can be kept for exclusive breeding purposes.
“Cloned horses can breed,” says Hinrichs. “They are basically normal horses. Breeding is the main reason people are cloning horses [in order] to save valuable genetics so they can produce foals from those lines. A very common reason for cloning is because an excellent champion horse is a gelding. By cloning him, you can keep the cloned colt intact and then are able to ‘breed’ to the gelding through his clone.”
She adds, however, that cloning is a technically difficult procedure that has a huge requirement in terms of equipment costs, the need for expert personnel, and access to a supply of oocytes. In the early days when Prometea was foaled, the researchers experimented with 841 reconstructed eggs. Of these, 22 grew into transferrable embryos and, of 17 embryos transferred to recipient mares, only Prometea was carried to term and delivered.
Lynx Melody Too is the cloned foal of the AQHA mare, Lynx Melody, a National Cutting Horse Association World Champion. Photo courtesy of ViaGen
“The early challenges were focused around embryo care and transfer,” says Russell. “When ViaGen began offering equine cloning, equine embryo technology was still very much around the utilization of fresh embryos. ViaGen has successfully developed high quality embryo freezing technology, and today, 100 percent of our equine embryos are cryopreserved and shipped to our embryo transfer locations. ViaGen transfers most of our equine embryos in Texas to a veterinarian clinic that has worked with us for more than ten years.”
In ViaGen’s first year, they saw a few foals with contracted tendons and a few foals were lost for a variety of reasons, which led to changes in the technical process. Russell says that many of the research institutions were struggling with foal health immediately following birth. The most significant challenge that remains is improving the pregnancy rate. However, success rates now are high with healthy cloned foals being born that require no special care. The company guarantees a 60 day old, genetically verified, healthy and insurable foal for their clients.
Understandably, cloning has its squirm factor. Breakthroughs in science have put tantalizing breeding strategies at people’s fingertips. But just because you can, does it mean you should?
For some people, the argument is simply that it just doesn’t feel right to experiment with Mother Nature. There is a real fear that the backlash down the road is for the prevalence of disease to lead to genetic mutations and that repeated breeding for a specific line and/or discipline may lead to a genetic bottleneck putting the breed’s healthy diversity at risk.
Cloning is not for every breed organization either. The Jockey Club will not register a cloned Thoroughbred, nor in fact will it register any horse conceived by any method other than live cover.
The American Quarter Horse Association recently won a lawsuit after it was sued by an owner of cloned Quarter Horses and their offspring for antitrust activity.
“The owner prevailed in US Federal Court,” says Russell. “However, the AQHA did appeal and won a reversal in the appeals court. Therefore, AQHA is allowed to continue their restriction against the registration of cloned Quarter Horses and their offspring.”
Russell says, though, that most international registries have welcomed cloned horses and their offspring into their registries, and see cloning technology as simply another breeding tool to be responsibly used by breeders to advance their performance goals. “The AQHA’s decision doesn’t appear to be having much impact on the decisions of other registries around the world. ViaGen continues to provide cloning services to large numbers of AQHA owners and they are using the technology to reproduce the DNA of their elite AQHA horses. Most events other than horse racing welcome foals produced with advanced breeding techniques. ViaGen is also providing our services to owners of most other breeds around the world including Thoroughbreds used for purposes other than racing, Olympic sport horses, polo horses, barrel racing horses, cutting horses, etc.”
Cloning has a broader value in animal reproduction, especially in the preservation of genetic lines for wildlife protection.
“The main justification I see for cloning is to preserve genetics as in valuable geldings or in the case of rare or endangered species or breeds so that you can expand the gene pool,” says Hinrichs. “You could use cells from animals that died decades ago (if the cells were recovered before or at death and frozen) that are under-represented in the population today.”
The Frozen Zoo at San Diego Zoo Conservation Research has been cryopreserving genetic material of endangered species since 1976. According to their website, some 15,000 sperm samples from 1,232 individual males representing 309 species are currently stored in the facility. In addition, oocytes (eggs) of 381 females from 177 species are also cryopreserved for fertilization and embryo transfer. Properly managed, frozen cells remain viable for decades. As an example, their researchers were able to achieve successful fertilization by injecting the endangered southern white rhinoceros oocytes with sperm frozen for over 20 years.
On September 15, 2008, the French genetic bank, Cryozootech, announced the birth of the colt Gemini, a clone of the Thoroughbred gelding, Gem Twist, regarded as one of the best show jumpers in history. In 2012, the first foal of Gemini was born. Photo courtesy of ViaGen
In addition, frozen viable cell cultures from over 9,000 individual animals representing nearly 1,000 species are also in the collection. Banked DNA and tissue samples are kept for research studies that can provide valuable information to sustainably manage and preserve wild populations in the future. In the fight against illegal trade in wildlife parts, genetic barcodes make it possible to identify the species used in the manufacture of bags, shoes, or meat traded at urban markets.
Russell says that ViaGen offers a genetic preservation service to provide options to horse, livestock, and pet owners wanting to preserve the ability to consider cloning in the future.
“We have thousands of animals represented in our cryopreservation bank and we are often cloning horses that had their DNA preserved as long as 20 years ago.”
He adds that cloning has a value when breeders are faced with the challenge of a subfertile mare or stallion in their breeding program. A technology known as equine intracytoplasmic sperm injection (ICSI) can be useful when the frozen sperm supply is limited or the mare cannot produce a pregnancy on her own. But ICSI results are highly variable and expensive. He says that the cloning route opens up easier future methods of reproduction such as artificial insemination (AI) or natural service.
“It can make much more economic sense to reproduce a proven stallion that has passed versus investing in the incredible expense and challenge to utilize a specialized technology such as ICSI with every breeding,” he says. “We find a similar situation with aging, elite mares.”
Cloning is not cheap and should be considered a long term investment.
“We are currently offering our equine cloning service for $85,000,” says Russell. “This is guaranteed to produce a healthy, genetically verified foal and [able to] pass an insurance exam at 60 days of age. ViaGen allows the client to pick up the foal alongside the recipient mare at 60 days of age and later return the recipient mare when the foal is weaned. For those recipient mares and foals that leave the country, ViaGen allows the client to retain the recipient mare. ViaGen agrees to keep the foal and recipient mare for up to 60 days for inspection, but many of the clients choose to take them home sooner so that they can raise them in their own management system.”
ViaGen has proven to have a positive track record with each cell line over the last ten years. As cloned foals grow and make their own contribution to performance and production careers, they are seeing an increase in demand.
For breeders thinking about cloning, the first step is a simple biopsy sample taken by their veterinarian. ViaGen provides a genetic preservation biopsy kit. Cells are grown in culture from the biopsy sample and, once complete, they are cryopreserved for future use. This keeps options open potentially for decades, and there should not be a need to re-collect a biopsy sample from the horse. Tissue, however, cannot be taken from a horse that has been euthanized. The fee for the service is $1,600 and the annual storage fee is $150 per animal.
How ViaGen’s Blake Russell Got Started In Cloning
ViaGen President Blake Russell was raised in the Quarter Horse racing business and spent his formative years with horses. He joined the company over ten years ago. Together with a group of experienced horsemen, they put together a list of great performing horses that had elite pedigrees but were unable to breed. Champion racing Quarter Horse Tailor Fit was on the top of the list. He was gelded as a yearling as his owners were more interested in a career at the racetrack than a breeding career. His dam, Silk Skirt, was a proven outlier and his sire, Strawfly Special, was one of the greats.
Tailor Fit went on to win the AQHA world racing title twice and earned well over a million dollars and a speed index of 110. He represented the traits most desired in performance horses with tremendous conformation, a level of heart and determination that is rarely seen, and elite speed. Russell said one look at his pedigree showed that those traits did not appear by chance, but were the result of a superior set of genes.
“I approached the owner of Tailor Fit following his retirement and she requested that I move forward with cloning him since I was carrying the passion for building a breeding program around him. I made the investment, and it has been a journey that is difficult to describe with words.”
The result? Pure Tailor Fit.
“Pure Tailor Fit (the cloned stallion) has been healthy and normal in every way. His athleticism is off the charts, and his personality traits draw everyone to him as the star attraction. ‘Fit’s’ oldest crop of foals turned two in 2016, and I have 20 of them on our place. We are extremely enthusiastic about their future as they seem to carry the attributes that started this journey in the first place.”
Pure Tailor Fit is the cloned stallion owned by Blake Russell, President of ViaGen, Texas. Pure Tailor Fit was cloned from two-time world champion racing Quarter Horse gelding, Taylor Fit. Photo courtesy of ViaGen
Racing the colts in the AQHA is forbidden since they cannot be registered, but Russell’s program is designed around producing barrel racing horses and exceptional roping horses.
“Each day ‘Fit’ or one of his babies confirms our decision to bring this pedigree back into production. People are often confused by cloning and don’t understand the value of identical twins. Full siblings are not a good reflection of the power of cloning. Pure Tailor Fit carries exactly the same breeding value as Tailor Fit would have represented if he had been allowed to remain intact and breed. The ability to take a high performer with an elite pedigree and no genetic defects and establish a breeding program is the reason for cloning technology to exist.
ViaGen Equine is cloning elite horses for Olympians, world class breeders, and owners of the world’s top equine athletes. However, I can step out my front door every day and see with my own eyes the power of this technology.”
Main photo: ©Thinkstockphoto/Svetlana Markelova