Answer:
This Question talks about the book titled To Kill a Mockingbird by Harper Lee published in 1960.
In chapter ten of the book, Jem and Scout went exploring with their air-rifles to see if they could find a rabbit or a squirrel. They noticed a dog showing that something is not right. Then reported to Calpernia who feared the dog is suffering the dog from rabies.
The dog represents the "madness", and Atticus will do anything to protect his family.
Atticus kills the mad dog with a shot between the eyes.
It fits with the symbolic nature of the incident by showing that some actions are EXTREMELY IMPORTANT.