The plot of the film focuses on a St. Bernard dog named Cujo who becomes rabid after being bitten by a bat while chasing a rabbit into it's warren. As the movie advances, the dog grows progressively more savage, turning on his master, Joe Camber and killing several people in the town of Castle Rock, Maine. A woman named Donna Trenton and her ill son, Tad, become trapped inside of their car on the Camber's property while Cujo terrorizes them in the midst of a terrible heat wave.
Actor Jerry Hardin has been in dozens of films and television projects, but he is probably best known for playing the mysterious Deep Throat on season one of the Fox Network television series The X-Files.
Actors Dee Wallace and Christopher Stone were married during production of Cujo. This is their second film together. They also played a husband and wife in the 1981 horror movie The Howling. Coincidentally, the two characters have a contentious relationship with one another in both films.
Producer Daniel H. Blatt makes a cameo appearance in the film as Doctor Merkatz.
Robert Craighead is uncredited in the film for his portrayal of Joe MaGruder.
Veteran voice actor Frank Welker was credited for doing the vocal effects for Cujo.
As with most film adaptations, there are notable differences between the movie treatment and the original novel. One of the most radical departures from the novel is the fact that Tad survives the experience. In the novel, he eventually succumbed to heat stroke. The manner in which Cujo dies is also slightly different. In the novel, Donna Trenton beats Cujo to death with a baseball bat. In the film, she bludgeons him with the bat, but finishes him off by shooting him in the head.
This is the first horror film work for assistant camera man Alexander Witt.