• Stress is the Stress Balls consequence of the dog to adapt to change, specifically the inability to respond appropriately to emotional or physical threats to the organism, whether actual or imagined. Homely stress sickness include irritability, muscular tension, inability to concentrate and a diversification of palpable reactions, such as headaches and accelerated heart rate.

From the late 1960s, Selye's concept started to be taken up by academic psychologists, who sought to quantify "life stress" by scoring "significant life events", and a extravagant chunk of research was undertaken to examine links between stress and disease of all kinds. By the late 1970s stress had become the medical area of greatest concern to the normal population, and more primary research was called for to preferred address the issue.