The world's first cloned horse was born eight years ago on May 28, 2003 at the Laboratory of Reproductive Technology in Cremona, Italy. Prometea was the successful outcome of 328 attempts to construct and implant a viable embryo.
To create Prometea, scientists took a skin cell from an adult mare which was fused with an empty equine egg. The mare then acted as a surrogate mother for Prometea - so giving birth to a carbon copy of herself.
Dr. Cesare Galli, one of the scientists involved, says cloning horses could help boost good breeds and might even help replicate equine champions. But he warns: "Although they will have the same genetic background, other factors such as training, the coach, their environment might have an effect."
Although the current regulations governing thoroughbred horses ban clones from competing, some industry experts believe this may not last.
The researchers fused the nuclei of skin cells taken from one male Arabian thoroughbred horse and a one Haflinger mare with eggs taken from slaughtered abattoir horses and emptied of their own DNA.
But success was far from guaranteed. Of the 841 successfully reconstructed male and female embryos, just eight male and 14 female embryos developed to the earliest "blastocyst" stage after seven days of culture.
And of the 17 embryos inserted into the mares, only four lead to pregnancies. Prometea, born after 336 days, was the only one to survive.
DNA tests confirmed she was a genetic twin to her mother. Galli says this was not planned and is surprising. The immune reaction by a mother's body to a fetus is thought to be important for the development of the placenta, he says, and an inadequate reaction was thought to result in abortion.
An immediate use of the cloning technique, says Galli, could be breeding from geldings - castrated male horses. Geldings that achieve success on the racecourse could be cloned, and the clone could then be used as a stud.
The team revealed their expectation that there will be resistance to the technology in choosing the clone's name. "Like Prometheus who took fire from God from Olympus, we hoped she would be brave to face these people who do not like what we do," Galli told New Scientist.