The pioneering experiment, conducted by Ian Wilmut and his associates at the Roslin Institute in Edinburgh, Scotland, was the first to replicate an adult mammal with cloning techniques (see sidebar). Although it took 276 unsuccessful attempts before Dolly was produced, the fact that the procedure eventually worked is a huge step forward in genetics research.

Unfortunately, the public’s perception of cloning has been colored by the fact that Hollywood got hold of the topic first-the term "clone" reeks more of science fiction than of science. Dolly’s birth also sparked a flurry of news stories and television movies about the possibility of cloning humans, and caused President Clinton to impose a moratorium on using federal funds in research for that purpose. A special panel formed by Clinton consequently recommended a ban on human cloning in June.

While the moral and ethical issues over cloning humans are a long way from resolution, the technology already is on its way to becoming established in animals. Dolly is the first mammal cloned from an adult, but other technologies have been used to produce clones from embryos for more than a decade. Horses have also been successfully cloned in this manner, although most of the research efforts have been concentrated on other, more lucrative species.

But as cloning techniques are refined and perfected, it stands to reason that enterprising equine breeders will soon want to hop on the bandwagon. After all, artificial insemination, in-vitro fertilization, and embryo transfer sounded like science fiction a few years ago too.

A clone is simply a genetic duplicate of another animal, much like an identical twin—they can think, function and reproduce just like any other animal. And just as identical twins can have distinctly different personalities and talents, clones also differ. It would be tempting to mount an entire U.S. Olympic dressage squad on clones of Rembrandt, or a show jumping team on clones of Gem Twist, but identical genes are no guarantee of identical performance.

It’s not yet known how much of a horse’s personality and competitive nature are inheirited from its parents, and how much is shaped by its environment. "A lot of times when we breed, it’s because I like the personality [of a horse]. I think a lot of that is genetic," said breeder Lisa Kunkle of Running Creek Ranch in Solvang, Calif.

But differences in training and handling would undoubtedly affect a clone’s performance and personality when compared to the original. Without the persistence and patient training of Carol Lavell, who knows if a clone of Gifted would be able to compete at Grand Prix? Nutrition, health, pre-natal development, and countless other environmental factors could also lead to significant physical differences between a clone and the original. Dolly, for example, is 20 percent bigger than the sheep from which she was cloned. These myriad outside factors can alter or affect an animal’s physical appearance and its temperament, but genes never change. So a clone’s genetic makeup will always remain the same as the original. And while a clone of Custom Made might not be a shoo-in to win at Badminton, he could do one thing the original never could—breed.

"I’d like to have Final Editon’s [clone] here as a stallion. That would be very exciting," said breeder and hunter rider Terry Brown, of Showcase Ltd. in Canton, Ga. "There are some really nice geldings, and we wish we could breed to them. That would be one of the plusses [of cloning]."

The majority of horses competing are geldings, and although mares who have proven themselves in competition can usually be counted upon to reproduce, they can’t put nearly as many offspring on the ground as a stallion.

So when a performance horse emerges at the top of its sport, breeders must usually look back to its parents for reproductive purposes, and hope that full brothers and sisters of star horses will continue the lineage. But cloning could allow a genetic replica of Gem Twist to stand at stud, or multiple Rox Denes to be used exclusively for breeding. The end result would be more foals produced from these top competitors with more of their valuable genes than would have been passed on through full brothers or sisters.

This scenario would not only be beneficial for breeders, but also for the equine species as a whole. The performances of animals in a population can typically be plotted along the lines of the classic bell-shaped curve—there are relatively few exceptional animals, and also relatively few inferior animals. Most are clustered right around the average.

Breeders attempt to move the curve a little farther toward the "exceptional" end with each generation by breeding only the best horses. But it’s still a very imperfect science—at present, there’s no way to control how genes from two parents will combine. "When we do selection, all we attempt to do is move the average of the group. We can’t breed for high-performance animals. All you can do is move that average" and hope to create more top horses, explained E.J. Pollack, a professor of genetics at Cornell University (N.Y.).

In other words, the fortuitous mixture of genes that produced Rox Dene will be lost once she’s bred and her genes recombine with those of a stallion. The resulting foal probably won’t perform quite as well as its mother, but it will likely perform better than average, and help move the curve even farther toward "exceptional".

This recombniation of genes was a brilliant idea of Mother Nature’s, helping to maintain variety in animal populations and allowing species to flourish by adapting to changing conditions over generations. But it is extremely frustrating for breeders, who strive to recreate the genes of the exceptional animals that lie along the outermost region of the bell curve.

"Reproduction works against us in selection," said Pollack. Cloning, however, eliminates breeders’ guesswork. "[With cloning], if you find those outlyers, you can maintain their sets of genes, rather than have recombination separate them again and have to rebuild them again," he said.

It would be dangerous, however, to rely on cloning exclusively. "Cloning just makes copies of something. It makes copies of the best thing you can find," said George Seidel, professor of physiology in the veterinary college at Colorado State University. "When you do sexual reproduction, sometimes you get better than the best. With cloning, you’re standing still genetically."

Brown puts it more simply: "If everyone wanted to own Secretariat, we never would have gotten Cigar. [Cloning] limits us from exceeding what we’ve already attained."

Narrowing the genetic pool also has dangerous consequences, as biologists who try to breed endangered species can attest. If all the members of a population are too similar genetically, they’re more susceptible to being wiped out by disease, and genetic disorders are more likely to surface.

In all likelihood, cloning will never become so pervasive in sport horse breeding that it would cause more than a ripple in the gene pool. Dolly proved the process can work in sheep, but it did take researchers 277 tries to get it right. And while there is intense interest in cloning production animals like sheep, pigs and cattle, there has been only minimal interest in cloning horses. The top authorities in the field say they don’t even know of anyone researching the possibility at the moment.

"I don’t see a lot of people banging the door down that want a cloned horse," said Dr. Edward Squires, director of the equine reproduction laboratory at Colorado State University. Squires also coordinates CSU’s "Preservation of Equine Genetics" (PEG) program, which was founded in 1996 to focus the university’s highly-regarded equine reproduction research efforts. "[Cloning research isn’t something] that we’re going to be directly involved in for the next several years," he said."It’s not as high a priority."

"Someone’s going to have to take the horse and see if the procedure would work," said Dr. Robert Godke, a reproductive physiologist and professor at Louisiana State University. But scientists are reluctant, said Godke, because horses are expensive and require more space and care than sheep and pigs. There’s also no major source of funding for research into horses. The big biotechnology companies support most of the current research in livestock, but they have no interest in horses.

"Unless the horse community is interested [and supports research], they can’t just call and say ’Can you do it?’ They need to get people together and make plans," Godke said. "I think people [in the horse community] should group together and talk about these new technologies. The ball is in the court of the horse organizations to increase their focus."

Cloned horses could certainly be useful in research—if all the subjects in an experiment were genetically identical, it would be much easier to test different training methods, or evaluate the effectiveness of various cooling-out strategies, or the effects of exercising horses on different types of footing. It could also add a whole new dimension to equitation classes if all riders competed on clones of one horse.

"It’s not totally science fiction," said Robert Foote, professor emeritus at Cornell who conducted some of the early reseach into cloning a decade ago. "But the probability of doing it tomorrow is low. When it becomes more efficient, I’m quite sure some of the wealthy will be attempting it."

But is this a technology that horse breeders will want as a whole? The Jockey Club won’t register Thoroughbreds that aren’t produced by natural cover, so cloned horses could never be used for flat racing. The cost of cloning would almost certainly be prohibitive, especially at first, and it would require faith on the part of the horse community that it will work and that the horses produced will be valuable.

"The sport horse industry isn’t into potential. A horse would have to go out and prove he’s close or better [than the original]," said Brown. "If you had a clone of Gem Twist, and maybe he jumps great but he hits the fences, well, what good is he? He’s not Gem Twist."

If the technology worked too well, however, "everybody in the grand prix would have a Gem Twist," said Kunkle, who feels cloning would be far out of most breeders’ leagues. "It’s going to be so expensive that it would be a completely different field than breeding," she said.

Although there’s still much research to be done, most scientists now think there’s no reason why cloning shouldn’t work in horses. One day, it may be as simple as drawing blood and sending it off to a laboratory. Sport horse breeders will probably have 10 or 15 years to decide how they want to use the technology, if at all.

While cloning may never become an everyday occurence in the breeding industry, it seems likely that it will find its way into the horse world somehow. Even if it’s only because of a few sentimenal folk who want to find a way to recreate a beloved companion, or favorite competition mount.

"I think the biggest application would be to people who jut want to have a single horse [cloned] when the one dies," said Seidel. "There’s a bigger market in emotion than anything else."

Where Did Dolly Come From?

When researchers separate the cells at this early stage, each one still has all the genes necessary to produce an entire animal. So eight identical sheep can be produced from one early embryo, for example. Scientists always believed that once a cell had differentiated to perform its specific function in the body, the genes within that cell could not be reprogrammed to grow an entire new animal. But Dolly proved otherwise.

Wilmut and his colleagues took the DNA (an animal’s unique genetic code) from the mammary cell of a 6-year-old ewe, and implanted it in an unfertilized egg taken from another sheep. All the DNA and genetic material had been removed from the egg cell, leaving the machinery for making a sheep embryo, but none of the instructions, which are provided by the DNA.

The egg and its new DNA were cultured for several days, and then implanted into another sheep that served as a surrogate mother. The egg divided as normal, producing a healthy lamb at the end of the pregnancy.

The lamb, Dolly, was a genetic copy of the sheep that provided the original mammary cell DNA, and the first clone produced from an adult rather than an embryo. In other words, she was like the identical twin of a sheep that had been born six years before.