Cujo - Stephen King

Once upon a time, not so long ago, a monster came to the small town of Castle Rock, Maine... Cujo is a huge Saint Bernard dog, the best friend Brett Camber has ever had. Then one day Cujo chases a rabbit into a bolt-hole.

Except it isn't a rabbit warren any more. It is a cave inhabited by rabid bats. And Cujo falls sick.

Very sick. And the gentle giant who once protected the family becomes a vortex of horror inexorably drawing in all the people around him...