Puppy represents youth, heedlessness, spontaneous affection and enthusiasm. It often represents a child, or feelings about a child, wanting a child, or being pregnant with a child. Also vulnerability or dependent needs. Like any young animal, it can depict your need to care for or love something, or be loved. What happens to the puppy, if neglected or mistreated, most likely indicates memories of pain from your own childhood, or neglect of vulnerable parts of yourself.
See also: Baby animal under Animals; Pet.