Caffrey, a black Persian cat became an inspiration to thousands after his video went viral. When Caffrey was three, he lost his left hind leg after being hit by a car. He got around great with just three legs for ten years.
Then his vet discovered a malignant tumor on his left front leg. His owner, Sue Greaves, couldn't bear the thought of putting him down or putting him through extensive chemotherapy with no guarantee of success so she had his leg amputated. The vet sought out opinions from his colleagues and they all said that Caffrey wouldn't be able to walk with both left legs missing and that he would be so poor that it wouldn't be worth living.
Well, Caffrey amazed them all when he started running around on his two legs, bounding about in the garden. He defied what others thought about him and managed to lead a normal life despite having no left-side legs.
source: Love Meow