A mountain lion with an unusual deformity of fully formed teeth growing out of its forehead was killed in the US state of Idaho.
The young male mountain lion was legally shot dead on 30 December after it attacked a dog on a resident's property in the rural Weston area, the Idaho Department of Fish and Game said.
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It ran off and was followed by a hunter to a place where the cat had retreated to the hills. Within three hours of the attack, it was killed. The dog involved in the attack survived.
Along with the teeth, the cat had what appeared to be small whiskers growing out of hard fur-covered tissue on the left side of its forehead.
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Idaho Fish and Game said it cannot explain why this abnormality developed on the mountain lion.
In a statement it said: "It is possible that the teeth could be the remnants of a conjoined twin that died in the womb and was absorbed into the other foetus. It is also possible that deformity was a teratoma tumour. These kinds of tumours are composed of tissue from which teeth, hair, and even fingers and toes can develop. They are rare in humans and animals. Biologists from the southeast region of Idaho Fish and Game have never seen anything like this particular deformity before."
Mountain lions are common in Idaho and a native game species. Because of their elusiveness and wariness, human encounters with the animals are rare. They can be legally hunted in the US state.