Double Exposure

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When Dolly, the cloned sheep, grew to maturity, she launched a thousand dreams. Would it be possible to clone a horse—a champion jumper, racer, reiner, or even the family favorite??

Let’s look at the possibility scientifically. According to Dr. Robert Godke of the Department of Animal Sciences at Louisiana State University, cloning is “…a type of asexual reproduction which includes both embryonic cell and fetal and adult somatic cell nuclear transfer.” Cloning using embryonic/fetal cells usually has a better success rate in the laboratory, but it’s possible to clone an adult horse, too. But it’s not easy.

To clone an adult horse, cells (e.g., skin cells) are taken from an adult horse and placed in a medium to grow a population of cells. Because there are insufficient nutrients in the growing medium, the cells become biologically inactive. At the same time, an unfertilized egg from a donor horse is prepared by having its nuclear material removed. This egg no longer has the all-important nuclear DNA, which is the material that makes each animal unique. A single adult donor cell is then placed inside the egg, and the membranes are fused together with a small amount of electricity. With a little luck, the cell will begin dividing, just as a viable embryo would. After a week, the egg is implanted into a surrogate mare, and eleven months afterwards, a clone is born.

To date, several mule clones have been successfully produced, and last year a Haflinger mare produced a cloned foal in Italy. An interesting aspect of this cloning is that the surrogate mother, in whom the reconstructed egg was implanted, was also the cell donor. In layman’s terms, this means that the foal was genetically identical to the mare that carried it to term. Currently, experiments are continuing to improve the process. “In my opinion,” states Godke, “cloning in horses is off to a good start. In cattle we sometimes see babies that are weak at birth, but with horses, all indications at this time are that cloning produces viable foals.”

For all its futuristic promise, cloning has its limitations.

Do you have a frame overo Paint that is exactly what you have been breeding for? Do you want another one with that exact coat pattern? Cloning, unfortunately, may not be the answer. Not long ago a domestic cat was cloned, and many experts were surprised that the resulting kitten did not share the same coat pattern. The theory is that coat patterns for mammals tend to be a random event that is determined in utero. For horses, the pattern may be similar but not exact, because it depends on what migration route is taken by the hair follicle pigmentation cells in the fetus.

Another common thought about cloning is that a long dead horse, a famous horse from a breed’s past, can be re-created. But it’s wishful thinking (at the moment) to expect that a thoroughbred farm could produce, say, a whole barn of Seabiscuits, or that a Quarter Horse breeder might fill his farm with Wimpy duplicates. When a horse has been buried for a long time, the DNA within the cells that is needed for cloning is often damaged or destroyed.

But, if a horse (or a key part) has been frozen—a leg bone was kept in a researcher’s freezer, say—there might be some viable cells in the bone marrow. In the near future, it may be possible to take these cells and produce a clone. Researchers at Texas A&M University recently did something similar when they cloned a calf from cells taken from a specimen that had been frozen for over a decade.

There are some very intriguing possibilities that arise with this new technology. Do you have a fantastic gelding, one that you wish had never been gelded? With cloning you would be able to make a duplicate, but with one small difference. Instead of a gelding, you would have an intact male. While your gelding continues to shine in the performance arena, you can breed mares with his clone.

A concern among some breeders is how cloning would impact the value of stock. For example, part of the worth of a world champion is that there is only one such horse. What if that horse were cloned and suddenly there were ten genetically identical copies? Would the price of the original horse decrease? Additionally, with environmental factors and different training methods figured into the equation, perhaps some of those ten clones would not be as spectacular as the original. Would this also drop the value of that world champion?

At an estimated cost of over $20,000 per clone, it is unlikely that we will see a lot of horse clones in the near future. Of course, as the technology improves, the price of cloning may drop. No doubt the technology offers some fascinating opportunities for the equine world.