Bull Calf In China Is Born With An Extra, Fully-Developed Leg On Its Back [Video]

A bull calf in China has quickly become an internet sensation after he was found to have grown an extra leg on his back. Despite the mutation, the young bull is developing normally and is doing just fine.

The unique calf was born on a farm in Heilongjiang Province in northeast China. At first sight, the animal looks perfectly well, save for the mutation on his back. The extra leg is fully-developed, complete with a cloven hoof and hangs on the right side of the body.

In a footage posted by Pear Video, the young bull is happily running around in the snow and interacting normally with other bulls and animals on the farm. In an interview with the said media outlet (via the Daily Mail), Wu Yujiang, the animal’s owner, said he would be happy to donate the bull to a zoo so that more people can see it.

Although uncommon, the calf’s condition is not entirely out of the ordinary. The mutation is a rare disorder called polymelia, which basically means having extra limbs. According to National Geographic, a 2002 study showed that out of 100,000 cattle born worldwide, only less than four come out with extra limbs.

Polymelia affects all kinds of animals, and there have been reports of chickens and frogs diagnosed with the disorder. The condition also manifests itself in humans.


The condition is not life-threatening, but giving birth to an offspring with extra limb can be difficult for the mother. While some calves with polymelia die in the uterus, some also survive to adulthood. In most cases, animal owners choose to have these extra limbs surgically removed.

In cattle, polymelia is believed to be caused by a hereditary gene disorder. For instance, Dr. Jan Pol, the lead veterinarian in the show The Incredible Dr. Pol, explained that polymelia in Angus cattle may be caused by a mutation of the NHL-RC2 gene, which is involved in blood clotting for cows.

Calf extra limb
Polymelia is a rare condition that affects cattle and other animals. [Image by Ingram Publishing/Thinkstock]

For some animals, however, polymelia may be caused by infection. In the western U.S., frogs are known to suffer polymelia after getting infected by a flatworm parasite known as Ribeiroia ondatrae. This parasite causes disturbances in the frog’s development and results in deformities.

[Featured Image by Ben Harding/Thinkstock]