the dogs used for this sort of thing bite and hold. it isn't like a pet biting with its canines or a pit bull biting and thrashing. the dogs are bred and trained to bite with their molars. the end result is a very hard but firm bite that causes less damage than you would think. this is why dogs are typically trained to target certain muscle groups that can take a bite without severe damage. this is why dogs typically bite upper arms, arm pit/chest area, thighs or calves.