Porcupines are very prevalent in our area and dogs (and some cats!) can't seem to resist going to check them out.  Porcupines cannot throw their quills, so the dog must get close enough to touch it.  Most of the time, the dog may only have a small number of quills, but we have seen many with hundreds.  The quills have microscopic barbs on the tips that allow them to work their way deeper into the dog's skin.  If your dog has less than ten quills, you may be able to pull them out by grasping them close to the skin with pliers and pulling straight out.  If your dog has a lot of quills or may try to bite as you remove them (it can be painful), then bring them in immediately to us or an emergency veterinarian for removal under anesthesia.  The longer they stay in, the more likely they are to break off under the skin and cause infections and problems later.