German Shepherd training, in my experience, can either be very difficult or a breeze, it all depends on how well they were socialized as puppies. Socializing a German Shepherd is extremely important and if done properly, these dogs typically do well in most situations. A lack of early socialization can cause German Shepherds to suffer from serious and crippling anxiety and some issues that could develop include leash aggression, aggression with strangers, separation anxiety, and resource guarding.