First cloned sheep put to death at lab

LONDON -- Dolly the cloned sheep was put to death Friday, after premature aging and disease marred her short existence and raised questions about the practicality of copying life.

The decision to end Dolly's life at age 6 -- about half the life expectancy of her breed -- was made because a veterinarian confirmed she had a progressive lung disease, according to the Roslin Institute, the Scottish lab where she was created and lived.

"We must await the results of the post-mortem on Dolly in order to assess whether her relatively premature death was in any way connected with the fact that she was a clone," said Richard Gardner, a professor of zoology at Oxford University and chair of the Royal Society working group on stem cell research and therapeutic cloning.

"If there is a link, it will provide further evidence of the dangers inherent in reproductive cloning and the irresponsibility of anybody who is trying to extend such work to humans."

Ian Wilmut, the leader of the team that created Dolly, said it was unlikely her illness was attributable to being a clone.

"The most likely thing is an infection which causes a slow progressive illness and for which there isn't an effective treatment," he said. "Sadly, we have had that in some of the sheep on the farm."

Coughing for a week

The institute's Dr. Harry Griffin said Dolly had suffered from a virus-induced lung cancer that was also diagnosed in the past few months in other sheep housed with Dolly.

Griffin said that Dolly had been coughing for about a week before the vet came Friday afternoon and conducted a CT scan.

She was born July 5, 1996, in a research compound of the Scottish institute, and the achievement of her creation -- announced Feb. 23, 1997 -- created an international sensation.

Researchers had previously cloned sheep from fetal and embryonic cells, but until Dolly, it was unknown whether an adult cell could reprogram itself to develop into a new being.

There are now hundreds of animal clones around the world, including cows, pigs, mice and goats, many of them appearing robust and healthy. But many attempts to clone animals have ended in failure.