Dates: Born 5 July 1996 and died 14 February 2003.
Why was she famous? The first cloned animal to be created from an adult cell.
Where did she live? At the Roslin Institute, University of Edinburgh.
Dolly's family: Dolly mated with a small welsh mountain ram and together they produced six lambs!
Why did Dolly die? Dolly died from an incurable lung disease that affects sheep known as SPA.
Did you know? Dolly was named after the legendary country and western singer Dolly Parton.
The development of the cloning technology was an extension of Roslin Institute's interest in the application of transgenic technology to farm animals. Transgenic mice have been available since early 1980s produced by a very sophisticated method of genetic modification through a technology using embryonic stem cells.
Cells in culture can be genetically modified in very precise ways: removing genes, substituting one gene for another, introducing a single base pair change in the genetic code. Cloning was therefore a potential alternative way of achieving the same end.
Dolly started her life, as with all other cloned animals, in a test tube. Once normal development was confirmed at six days, the embryo, that was eventually to become Dolly, was transferred into a surrogate mother. The pregnancy went without a problem and Dolly was born on 5 July 1996.
The birth of Dolly was kept under wraps until the publication of the Roslin Institut's research results could be prepared. Once these results were released, the full impact of the discovery became plain to all the animal carers, as the world’s press descended on Roslin.
In an attempt to allow Dolly to have as normal as life as possible it was decided that she should be allowed to breed. A small welsh mountain ram was selected as her mate and between them they successfully produced six lambs. Their first lamb, Bonny, was born in the spring of 1998. Twins followed the next year and triplets the year after that.
In the autumn of 2001, Dolly was seen to be walking stiffly. X-rays confirmed that Dolly did indeed have arthritis. It fuelled the suspicion that cloned animals were destined to age prematurely. The cause of the arthritus was never established but daily anti-inflammatory treatment resolved the clinical signs within a few months.
Although the arthritis was a concern for the animal carers at Roslin, a much more serious problem was feared. In January 2000, one of the cloned sheep, Cedric, died. The post mortem revealed that Cedric had died of sheep pulmonary adenomatosis (SPA). This disease is caused by a virus that induces tumours to grow in the lungs of affected animals and SPA is incurable.
She remained healthy until Monday 10 February 2003, when an animal care worker reported that he had noted Dolly coughing. Full veterinary examinations and blood tests were conducted but failed to establish a diagnosis. A CT scan was carried out on 14 February 2003. The scan confirmed the team's worst fears: tumours were growing in Dolly’s chest.
Since a general anaesthetic had been necessary to perform the CT scan it was decided that it would be best if Dolly did not regain consciousness and she was put to sleep.
Dolly was also important because she captured the public imagination. The idea that there might be an exact copy of oneself somewhere in the world is a theme that has been pursued in science fiction and the prospect that it might be possible to clone a human being excited a lot of speculation and interest.