The title of Stephen King’s novel about a rabid St. Bernard is Cujo.
Published in 1981, Cujo centers on a large, normally friendly dog who is bitten by a rabid bat. The infection changes Cujo’s behavior and turns him into a deadly threat around the rural community of Castle Rock, Maine. The novel’s horror comes from an ordinary animal becoming dangerous through disease rather than through supernatural transformation.
The story follows several connected characters, including Donna Trenton and her young son Tad. Their situation becomes especially desperate when their car breaks down near the home of mechanic Joe Camber, whose dog Cujo has become infected. The confined setting intensifies the danger and the family’s vulnerability.
Cujo is also part of the wider Castle Rock setting that appears in several King works. Readers may confuse the novel with Christine, another King story involving a dangerous vehicle, but Cujo’s central threat is a St. Bernard. The book was nominated for the 1982 World Fantasy Award for Best Novel.