Dolly the sheep, and now Snuppy the puppy - what's next?

Since the first animal, Dolly the sheep, was cloned in 1996, scientists been able to clone pigs, cattle, mice, rabbits, horses and cats.

But though many have tried, no one has ever managed to create a genetic double of a dog.

But now South Korean researcher Woo Suk Hwang and his team at Seoul National University have introduced Snuppy the puppy, an animal whose entire genome has come from a single cell from the ear of a three-year-old Afghan hound.

The arrival of Snuppy has surprised rival cloners in the U.S.and produced some rather grudging admiration.

The achievement of the Korean scientists has finally proved that cloning a dog is possible, but not that easy.

John Sperling, the billionaire who co-founded the Genetic Savings & Clone (GS&C), in the U.S., has spent seven years and more than $19 million trying without success to clone a dog.

Another researcher Mark Westhusin, of Texas A&M University, whose team cloned a cat at its second attempt in 2001, abandoned the dog-cloning project years ago.

George Seidel Jr. of Colorado State University, a reproductive physiologist, refused to even try, when the company approached him.

Apparently the problem with dogs is that harvesting their eggs is extraordinarily labor intensive, as viable eggs have to be extracted surgically, and it is not possible to just implant them at will in a surrogate dogs; hundreds, or even thousands, of dogs have to be monitored daily to establish when they come into heat.

Hwang's team worked seven days a week for 18 to 20 hours a day, in order to be ready to collect oocytes at any time.

Hwang says cloning Snuppy took almost three years and cost millions of dollars.

He ultimately aims to create a research model for making stem cells that could cure disease in people.

He says, dog cells are more similar to human stem cells.

Company scientists at GS&C are still trying to clone a dog, but Ben Carlson, a company spokesman, says it will be very expensive.

Apparently GS&C has stored the DNA of several rare or endangered animals in its cryogenic freezers.

It does appear however that the biggest breakthroughs in cloning are now coming from Asia.

Hwang does not say what he now plans, but the next logical step would be to clone a primate.