Today, that divide is rapidly closing. Modern veterinary science has recognized that an animal’s mental state is inextricably linked to its physical health. In the contemporary clinic, behavior is no longer just a sidebar to physical exam; it is recognized as the "fourth vital sign," alongside temperature, pulse, and respiration.

Pain is one of the most common underlying causes of behavioral change. In veterinary medicine, we now understand that many "bad behaviors" are actually pain responses:

How a Would-Be Baker Became the Queen of Veterinary Behavior