I come across these every now and again. Rarely see the culprits, which is fine. A close encounter too prickly for my liking, but it always amazes me they can eat and digest bark. The first month my dog Paddy was living here he met one and came away with a snout full of quills.
I was at work in Santa Fe when he came home that day. My parents were visiting, so they gingerly yanked them out using a pair of pliers, one at a time, whenever he settled down to try to get some sleep. Only once more did he get too close to one, coming away from that encounter with a single, small quill barely lodged in the tip of his nose. No pliers required.