This story is quite peculiar. We dont know anything about the woman yet were driven to feel empathetic toward her bwcause she does some very tiring wirk and she technically csn never finish it because of the dog but she dosent know that. At the same time we understand why the dog behaves this way and we probably would too since its stated that the world could end if she finishes her work. I think almost amy other domestic small animal couldve been chosen like a cat or a bunny. Since they simply need to be small enough to be able to take the quills out with acurracy and not ruin it. The dog is basically concerned and saves the world in the easiest way possible without harming the poor small old woman.
The Sioux people used to say that if the old woman ever finishes her blanket strip, then at the very moment that she threads the last porcupine quill to complete the design, the world will come to an end.
This is interesting to think about as just one simple myth could define something as complicated as the end og the world. Its quite interesting