This talk of enhanced Cujo reminds me of Dean Koontz' Watchers, which had a super smart Golden Retiever, and was adapted into a whole mess of bad movies.
He's written a shit-ton of books over the years, so it'd make sense. There was also a time where a ton of bad King adaptations were coming out one after another.
The closest possible competitor I can think of is Stan Lee with how many times the various Marvel properties he created have been adapted into cartoons, movies, live-action TV and so on, but even that example is stretching it since many of them weren't solely created by him.