In children, we see an aversion to social contact with both peers and adults that can manifest as crying and / or visibly fearful responses like shaking and sweating. (scirp.org)
Especially if subjected to physical or verbal abuse in the past, your new dog may show fearful responses. (paw-rescue.org)
To reduce the possibility of fearful responses as a puppy grows and matures, it is essential to expose young puppies to many stimuli (people, places and things, sounds, smells, events). (cindysschnauzers.com)