When pit bulls are violent toward people, it generally indicates a problem, perhaps lack of socialization with humans, trauma, neglect or issues with training. (dogcare.dailypuppy.com)
And while cats must be trained as well, they require a lot of socialization in order to adapt to their surroundings. (petsforpatriots.org)
The final sensitive period of the socialization period is when pups learn to speak «human». (safarivet.com)