your dogs sensitivity is not likely caused by its past. Pitbulls are VERY sensitive dogs, and often wear their feelings on their sleeve. i have had my pitbull soldier since he was a month old puppy and he is now 7 years old. Although there is rarely ever a need to disciplin him or correct him at this age, he gets very pouty if i dont give him MOST of my time and attention. your pitbulls actions are pretty common, even among dogs who were raised properly.
