The Importance of Animal Welfare Science in Animal Research and One Health

Animal welfare has been a concern in many societies for decades now. For example, Ruth Harrison published her impactful book, Animal Machines, in 1964, which described the housing and management conditions of farm animals at the time and highlighted the welfare issues observed [1]. There are different definitions of animal welfare in published literature, but in general they relate to the experience of the animal from external (e.g., housing) and internal (e.g., hormone) factors, which are integrated to form the animal's current state or welfare status [2]. Focus has often been on minimizing negative experiences, such as the Five Freedoms framework, which states that animals should have freedom from thirst, hunger, and malnutrition; freedom from discomfort; freedom from pain, injury, and disease; freedom from fear and distress; and freedom to express normal behavior [3]. However, more recently this has been expanded to also include promotion of positive animal welfare, where animals do not just have reduced suffering but also have opportunities to have positive or rewarding experiences [4]. The resultant effects of housing and management on mental state are now often incorporated in animal welfare frameworks [5]. Additionally, animal welfare can be considered on a continuum throughout the animal's life, with the goal that animals should at least experience ‘a life worth living’ overall, and we should strive to provide them ‘a good life’ [6].