Why is buck able to completely follow " The call of the wild"?

He lives in Santa Clara Valley with his owner, Judge Miller. He is a domesticated dog until he is stolen and sent to Alaska where strong sled dogs are in demand. Buck undergoes a series of adventures where he must shed his pampered doggy past and learn what it means to be wild. He must reject his domesticated past and subservience to man with his final calling to be wild and free. Buck must find his inner-wolf through many trials and tribulations in order to finally hear his, “call of the wild”.