Animal welfare methodology and criteria.

The concepts of welfare and comfort are relatively new to the veterinary field. For a long time, it was thought that these concepts were equivalent to the absence of pain, stress and suffering, but such a comparison is imprecise. In addition, the application of objective and quantitative criteria to pain and stress has not been as easy as was initially thought. The concept of stress has evolved considerably since the term was coined by H. Selye in the 1950s to denote the non-specific response of an organism to any excessive demand. It is now well established that neurohormonal stress responses do not depend on the physical nature of the stressor, but on the way in which this is perceived and presented to the animal which is exposed to such a situation. The study of stress reactions therefore provides an insight into the subjective world of the animal. Suffering cannot be confined to physical suffering alone, as animals are capable of undergoing mental suffering. Research into the welfare and comfort of animals implies a study of the ability of an animal to express basic species-specific behaviour in the environment in which it is placed. Any discomfort produced by husbandry conditions may be detected through anomalies in the expression of this behaviour, or by examining preferences expressed by animals offered a free choice. All of these elements provide an objective and quantifiable approach to welfare and suffering in animals. But society must determine what is acceptable or not on the basis of these criteria.