The lamb was born on the farm of Dave Callaghan on Friday in Canterbury, the Ashburton Guardian reported. He told the newspaper it was one of a set of twins and unlike anything he's ever seen.
The lamb has four front legs, two of which are useless, and three hind legs that all work, the report said.
The animal was taken to Canterbury Vets, where Dr. Steve Williams examined it. He said its a one in several million occurence.
He said there was a "misprint" in embryo formation that caused not only the multi-limbed polydactyl condition, but also made the sheep a hermaphrodite -- having genitals of both sexes.
The final genetic insult is that part of the lamb's bowel is missing, which prevents it from excreting. Williams said the animal would have to be euthanized.
"To keep it alive is probably inhumane really," the veterinarian said.