Cujo is a horror novel by Stephen King, published by Viking in 1981. The book tells the story of the middle-class Trenton family and rural Camber clan in Castle Rock, Maine. Mundane marital and financial difficulties plague disgraced advertising man Vic Trenton and his adulterous wife Donna. Their domestic problems are dwarfed by mortal danger when Donna and her four-year-old son Tad are terrorized by a rabid St. Bernard named Cujo. The novel was adapted into a 1983 film of the same name.
The book is a semi-sequel to King's earlier work The Dead Zone. "Cujo" makes several specific references to the events and characters of "The Dead Zone," even so much as to lead the audience to believe that Frank Dodd (committed suicide in The Dead Zone) is possessing Cujo. King made later reference to the dog in his 1983 novel Pet Sematary, in which a character briefly alludes to "a big old St. Bernard (that) went rabid downstate a couple of years ago and killed four people", a clear allusion to the events of Cujo. Similar references appear in King's later novel Needful Things, as well as his novella The Body, from Different Seasons.
A reference to Cujo is made in the short story Mrs. Todd's Shortcut, where it mentions Joe Camber getting killed by his own dog.