| Spoiler warning!|
This article contains plot details from one or more of the books.
So far, the gnaw bite has only been used once. In Shadow Wolf, Faolan was supposed to recieve the bite from Heep, but he was frightened by Faolan's swirled design on his paw. Faolan was being punished for his "profane" actions in a previous byrrgis, and Heep had been chosen to do it as it would add more humiliation to Faolan.
The only known purpose of the gnaw bite is to inflict punishment to a gnaw wolf when he or she steps out of his or her rank or behaves like a higher rank wolf. This punishment is most likely to represent or remind the gnaw wolf that he or she must follow pack rules and that they are higher in rank than no one in the rest of the clan and pack.