We can rebuild it ... we have the technology. Here's the story of Coal, an eight-and-a-half year old dog whose left paw was amputated because of cancer. Instead of putting him down, his owner Reg Walker spent a lot of money to fit him with a bionic leg:
A beloved pet bulldog has been fitted with a £10,000 bionic leg, which will help advance prosthetic techniques used to help bombing victims. [...]
The titanium alloy used mimics animal hide, allowing the skin and the bone from above to seal the metal implant below without it being rejected by the body.
Link - Thanks TwoDragons