On Feb. 14, 2003, a CT scan was performed on Dolly and it was determined that 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 an overdose of an anaesthetic agent was administered to end her life.

Dolly was born in 1996 at the Roslin Institute in Edinburgh, Scotland becoming the world’s first mammal to be cloned from an adult somatic cell. Dolly’s birth was not revealed to the public until Feb. 3, 1997. Dolly was allowed to breed. A small welsh mountain ram was selected as her mate and between them they successfully produced 6 lambs. Their first, Bonny, was born in the spring of 1998. Twins followed the next year and triplets the year after that.