Sandy and Jim learned a lot about Porcupines on their wildlife trip. Did you know?
Porcupines do not throw their quills.
Quills are really like hair.
Quills are meant to only go in, so the have rachet like ends. An animal would have no way to remove the quills. The quill would then move through the animal's body under the skin to the heart or lungs and then the animal dies.
A person can actually easily remove a quill as they just pull out. For example: Mario was with a friend watching Porcupines and the friend got a quill in his arm. Later that day when the quill was remembered it had disappeared. 7 months later the friend found it in his shoulder while bathing. So the quill had moved through his body but not to a critical organ like the heart, because he was human.
Mario commented if his friend bathed more often he would have found the quill earlier. Ha! Ha!