Prometea, the world’s first horse clone, turns two years old this month. Italian researcher Cesare Galli, DVM, of the Laboratorio di Tecnologie della Riproduzione-Consorzio per l’Incremento Zootecnico (LTR-CIZ) in Cremona, says the filly is completely healthy and shows no signs of being compromised in any way because of her clone origin.

The donor mare from which skin cells were used for Prometea’s cloning carried the Haflinger filly. Many individuals have asked The Horse why doesn’t Prometea look exactly like…well, herself? Galli says, “If you look now, the only difference is the list (white mark) on the head: it is wider in Prometea. The legs were different when she was born, but not now. The cells that give pigmentation can migrate differently–it is very evident in black and white cattle where even monozygotic twins are never identical.  

“Also, Pieraz 2 now is brown, but it will turn greyish like Pieraz when it grows up, but this is absolutely normal,” he added, referring to the second horse clone (see “American Horse Cloning Project Successful,”

The limiting feature to cloning at this point still seems to be its efficiency. “It is not easy to clone horses,” said Galli. “You need large numbers to be successful–last year (2004) we only had one pregnancy that went to term, but the foal died 36 hours later of septicemia. Pieraz 2 resulted from the transfer of 34 embryos into 12 recipient mares. Three pregnancies were established, but only one went to term.

“We are trying to understand how to better reprogram the somatic cells (non-sex cells) during the cloning procedure, and this will make more viable embryos that will result in higher birth rates,” he added.