The dog in Stephen King’s Cujo is named Cujo. He is a large Saint Bernard owned by the Camber family in Castle Rock, Maine, and the title character of King’s 1981 horror novel.
At the beginning of the story, Cujo is a friendly family pet and a beloved companion to young Brett Camber. His behavior changes after he chases a rabbit into a cave and is bitten by a rabid bat. The infection turns the normally gentle dog into a deadly threat, trapping Donna Trenton and her son Tad inside their car near the Camber auto garage.
The name is not a reference to a breed or a generic nickname: Cujo is the dog’s proper name. King reportedly based part of the novel’s inspiration on an encounter with an aggressive Saint Bernard at a Maine repair shop. The book was published in 1981 and adapted into a film released in 1983, helping make the character one of horror fiction’s most recognizable animals.