“Free will was not a factor.”
Horror in the ‘real world’, whatever that may be. Here the monster is a rabid dog, a kind dog that didn’t want to harm anyone but made the mistake of chasing a rabbit into a bat cave. Naturalistic, pessimistic and not entertaining in the ordinary sense of the word, it’s a good example of one of the things that make King great; he doesn’t write what the reader wants him to, but what the story demands.