I don't remember any werewolf being mentioned in the books - there were only similar creatures - like Nivellen in
Grain of Truth from
The Last Wish or striga. Some "inteligent" or "human" monsters resulted from strong curses (strigas and possibly also the werewolfs)), others (like vampires) weren't original to Geralt's world. In
Baptism by Fire Regis nicely explains to Marigold how many vampires would have been in the world, considering their original number of 200, their arrival about 500 years ago and the fact that each vampire drinks blood only during the full moon = over 20 millions of vampires ;D So, most likely there is no a single species of a moster that would reproduce in that way.
