Explanation: Further before this the passage says the Dog's neck was worn and the skin was chafed. The Dog also doesn't want to tell Wolf what it is so it can be assumed it's something the Dog doesn't want Wolf worrying about.
The woman chose to burn herself along with her books because perhaps she would rather die than be deprived of the knowledge she was restricted if she lived. Montag saw this as shocking and sees the power the books hold over some.
