History of animal testing
In 1996 Dolly the sheep was born, the first mammal to be cloned from an adult cell. The process by which Dolly the sheep was cloned utilized a process known as nuclear transfer applied by lead scientist Ian Wilmut. Although other scientists were not immediately able to replicate the experiment, Wilmut argued that the experiment was indeed repeatable, given a timeframe of over a year.
Dolly (sheep)
On 14 February 2003, Dolly was euthanised because she had a progressive lung disease and severe arthritis. A Finn Dorset such as Dolly has a life expectancy of around 11 to 12 years, but Dolly lived 6.5 years. A post-mortem examination showed she had a form of lung cancer called ovine pulmonary adenocarcinoma, also known as Jaagsiekte, which is a fairly common disease of sheep and is caused by the retrovirus JSRV. Roslin scientists stated that they did not think there was a connection with Dolly being a clone, and that other sheep in the same flock had died of the same disease. Such lung diseases are a particular danger for sheep kept indoors, and Dolly had to sleep inside for security reasons.