Chanel #5 the American Bulldog was born with a leg where her tail would normally be located. Ultrasounds have proven that it is indeed an extra leg with an ankle bone.
How common is Polymelia in animals?
Polymelia is a very rare congenital disorder that results in the presence of extra limbs on an animal. While it can occur in any species, it is most often seen in reptiles, amphibians, and fish. In some cases, the extra limbs are functional and fully developed. In others, they are vestigial and may be little more than tiny flaps of skin. The condition is caused by a mutation in the genes that control limb development, and it is believed to occur in only one out of every million births. Given its rarity, there is still much that scientists do not know about Polymelia. However, ongoing research is providing new insights into this fascinating condition.