The mortally wounded Cujo lunges, but Donna manages to retrieve the sheriff's revolver from the counter and shoot him in the head, killing him. As he starts to revive, a barely alive Cujo uses the last ounce of his strength to jump through a window. She takes him inside and gives him water. Donna is traumatized and throws the apparently dead dog off of her and uses the sheriff's revolver to break her son out of the car. However, when the dog jumps on her, she jams the broken end into Cujo's stomach, impaling him. She beats the dog with the blunt instrument, but it breaks when it strikes Cujo's face. Luckily, Donna is able to grab a discarded baseball bat from a junk pile and fend the dog off. She makes a daring escape from the car and Cujo attacks. Meanwhile, Tad is dying of severe dehydration and Donna decides that she has to do something or else her son will die. Luckily, the sheriff arrives, only to be savagely mutilated by Cujo after a brief struggle. Cujo bites Donna in the leg when she tries to escape and get help and she barely survives the merciless and destructive attack. When the phone rings, Cujo flies into a rage and viciously attacks the car, breaking a window in the process. By this time, Cujo is now completely covered in blood, grime, froth and mucus, and the smallest things could set him off.

When Donna Trenton and her son, Tad, go to the Camber's farm for an auto repair, they are attacked by Cujo and spend three days in their car hiding from him. For the next few days, he became very bloodthirsty and dangerous, eventually killing Gary Pervier and his owner, Joe Camber.

During the events of the novel, Cujo was bitten by a bat and got rabies from it.

Cujo by Stephen King