Stephen King isn’t an author who writes sequels to his works, though he has written a couple, and he once announced that he had written a sequel to Cujo – but what happened to it? The King of Horror’s reign started in 1974 with the publishing of Carrie, which gave readers a taste of the type of stories they could expect from him as well as of his writing style, but no one could have been prepared for the variety of horror stories that King would bring after that.

https://screenrant.com/stephen-king-cujo-sequel-what-happened/