Moving Beyond the Absence of Pain and Distress: Focusing on Positive Animal Welfare.

For many years, researchers, veterinarians, animal ethics committees, and regulators have focused on minimizing pain and distress as a primary goal of refinement when working with animals in science. More recent publications as well as a shift in animal ethics and public opinion have emphasized promotion of positive affective states, culminating in the concept of positive animal welfare. Robust measures are required to know when positive animal welfare states are occurring, and a number of measures are proposed and discussed. Regardless of whether there are newer methods available that focus exclusively on measuring positive affective states, consistent consideration of research animal behavioral programs, refinement, and adopting periodic stand-alone animal welfare assessments for all species involved will help to push the care and practices of research animals towards an increased focus on positive animal welfare.