When I was a med student, I studied animal models for human stress and depression. The best animal model of what a psychopath does to others is that of the rodent resident-intruder paradigm. In this model, males are introduced into the home territory of other males, they experience social defeat and are removed before they are injured. Repeated exposure to this situation produces a defeated animal who is chronically submissive and gives up without a fight whenever he encounters other males. Below is the posture of a defeated mouse.
The physiology of this defeated rodent resembles human depression very closely. The defeat state can be reversed with antidepressants. Defeat is associated with elevated stress hormones, immune dysfunction and learned helplessness.