Dolly the sheep clone dies young

The news was confirmed on Friday by the Roslin Institute, the Scottish research centre which created her.

A decision was taken to "euthanase" six-year-old Dolly after a veterinary examination showed that she had a progressive lung disease, the institute said in a statement.

" She was not old - by sheep standards - to have been put down "
Dr Patrick Dixon, expert on ethics of human cloning

Dolly became the first mammal clone when she was born on 5 July 1996.

She was revealed to the public the following year.

Post-mortem

Dr Harry Griffin, from the institute, said: "Sheep can live to 11 or 12 years of age and lung infections are common in older sheep, particularly those housed inside.

"A full post-mortem is being conducted and we will report any significant findings"

Dolly was a sheep created totally by design - even her name was picked specifically to be appealing.

It came about during the latter stages of labour when Dolly was born.

Stockmen involved in the delivery thought of the fact that the cell used came from a mammary gland and arrived at Dolly Parton, the country and western singer.

Cloning row

Her birth was only announced seven months later and was heralded as one of the most significant scientific breakthroughs of the decade.

But it also prompted a long-running argument over the ethics of cloning, reaching further levels with the latest allegations of human cloning.

Dolly, a Finn Dorset, bred normally on two occasions with a Welsh mountain ram called David.

She first gave birth to Bonnie in April 1998 and then to three more lambs in 1999.

But in January last year her condition caused concern when she was diagnosed with a form of arthritis.

Museum piece

The condition would usually be expected in older animals and another debate erupted over what could properly be judged as Dolly's true age, and the risks of premature ageing in clones.

Professor Ian Wilmut, who led the team that created her, said at the time that the arthritis showed their cloning techniques were "inefficient" and needed more work.

Dr Patrick Dixon, a writer on the ethics of human cloning, said the nature of Dolly's death would have a huge impact on possibility of producing a cloned human baby.

" If there is a link, it will provide further evidence of the dangers inherent in reproductive cloning "
Professor Richard Gardner

He said: "The real issue is what Dolly died from, and whether it was linked to premature ageing," he said.

"She was not old - by sheep standards - to have been put down."

'Profound effects'

Speaking to BBC News 24 on Friday, Prof Wilmut said Dolly's birth should be the important issue.

"The fact that we were able to produce an animal from the cell of another adult - it had profound effects on biological research and in medicine."

Professor Richard Gardner, chair of the Royal Society working group on stem cell research and therapeutic cloning, said: "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.

"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."

Dolly has been promised to the National Museum of Scotland and will be put on display in Edinburgh in due course.