Deformed Cougar
This photograph was sent to biologists, showing a cougar with teeth growing out of the back of its head Idaho Department of Fish and Game

This cougar has teeth and whiskers growing out of the back of its head, leaving experts confused. Biologists have speculated that the facial features grew twice, due to the growth of a rare tumour which encourages new body structures.

The cougar was hunted in Idaho, US, and was immediately brought to conservation experts at the Idaho Department of Fish and Game in line with state law. These experts are required to remove a single tooth from a hunted animal to gather data on its age, but they did not know where to begin when they discovered a secondary set on the back of the cougar's head.

"In the process of harvesting the animal, we had an officer check it, and we determined something really interesting was going on," Idaho Fish and Game spokesperson Jennifer Jackson told

The deformity appears as a muscle growth, with thick tissue, teeth, whiskers and body hair growing out of it. The experts suggest that it may be the result of a teratoma – a tumour which is composed of tissues that appear in places where they should not appear. Teratomas have been reported in humans, as bone, hair and teeth are found in bizarre places including the brain.

The Idaho Department of Fish and Game sent photographs to biologists for their opinion on the deformity. It turns out they were just as surprised as everybody else.

"It has all of us scratching our heads," said Zach Lockyer to the Idaho State Journal. "It's a bizarre situation and a bizarre photo."

The biologists in Idaho say they have never seen this type of deformity before. That said, they do have a few other theories behind its occurrence.

They suggest it could be the remains of a conjoined twin that failed to mature in the early stages of development. The cougar would then have absorbed the twin, leaving its mark on its body as it grew. However, they still believe a teratoma is the most likely cause of the deformity.

The cougar's corpse is currently still with the hunter, who killed the animal on 30 December in Franklin County, Idaho. The hunter plans to have the cougar stuffer and preserved by a taxidermist. Lockyer said: "We may never know why those teeth are there."