A mountain lion with a bizarre deformity — teeth and whiskers growing out of its forehead — has been shot in Idaho.

The male mountain lion, also known as a cougar, was legally killed by a hunter on Dec. 30 about 13 kilometres southwest of Preston, Idaho, the Idaho Department of Fish and Game said in a statement released Friday.

"The mountain lion had an unusual deformity — fully-formed teeth and what appears to be small whiskers were growing out of hard fur-covered tissue on the left side of the animal's forehead," the statement said.

The department, which said its biologists had never seen anything like it, offered two possible explanations:

  • The teeth could be from a conjoined twin that died in the womb and was absorbed by the surviving twin.
  • The deformity could be a rare kind of tumour called a teratoma that can sometimes develop teeth, hair, and even fingers and toes.

The hunter targeted the animal after it attacked a dog on a landowner's property.