Wolves of Darkness by Jack Williamson
When Clovis McLaurin received an urgent letter from his father, Dr. Ford McLaurin, he rushed in the dead of winter to his father's ranch. Clovis arrives to find the local townspeople are being attacked and killed by a pack of wolves. As he journey's to his father's ranch, a scientist who has been doing revolutionary experiments, he is attacked by wolves. But wolves are not the only thing running with the pack. Stella Jetton, the daughter of his father assistant, is running with the wolves dressed in only a silk slip in the bitter cold. Clovis recognizes the blood-stained face of the girl that he loves--except for those strange eyes--those are not Stella's eyes. How could his father's experiment untap the unimaginable horror that Clovis is about to confront?