CujoEditDuring the events of the novel, Cujo was bitten by a bat and got rabies from it. For the next few days, he became very dangerous, eventually killing Gary Pervier and Joe Camber. When Donna Trenton and her son, Tad, go to the Cameber's farm for an auto repair, they are attacked by Cujo and spend three days in their car hiding from him. By this time, Cujo is now completely covered in sweat, blood, grime, froth and mucus, and the smallest thing could set him off. When the phone rings, Cujo flies into a rage and viciously attacks the car, breaking a window in the process. Cujo bit Donna in the leg when she tried to escape and get help, and she barely survived the merciless attack. Luckily, the sherriff arrives, only to be killed by Cujo after a brief struggle. Meanwhile, Tad is dying of severe dehydration and Donna decides that she has to do something or else her son will die. She makes a daring escape from the car and Cujo attacks. Luckily, Donna is able to grab a discarded baseball bat from a junk pile and fend the dog off. She beats the dog with the blunt instrument, but the bat is merely broken when it strikes Cujo's face. Cujo lunges, and she falls backwards. However, when the dog jumped on her, she jammed the broken end into Cujo's stomach, impaling him. Donna, traumatized, throws the apparently dead dog off of her and uses the sherriff's revolver to break her son out of the car. She takes him inside and gives him water. As he starts to revive, a barely alive Cujo uses the last ounce of his strength to jump through a window. The mortally wounded Cujo lunges, but Donna manages to retrieve the sherriff's revolver from the counter and shoot him in the head, killing him.
In the book, Cujo's death is much more graphic. The end showdown is the same, but when Donna breaks the bat, she impales him in the eye with the sharp broken end, killing him instantly.
Along with the posessed automobile Christine he makes a cameo appearence in "Cat's Eye" where he chases the titular cat General. He kills with multiple bite and scratch wounds.