Animal welfare is the subject of rapidly increasing concern in most countries in the world and this concern is resulting in changes in the ways in which animal users keep and treat animals. The welfare of an individual is its state as regards its attempts to cope with its environment. This includes the state of all coping systems, including those responding to pathology, various behavioural and physiological responses and processes in the brain. Welfare includes health and the extent of positive and negative feelings. The statement that welfare means being in harmony with nature is not a definition of welfare that is usable in welfare assessment, whilst the view that welfare includes the extent to which the animal might be in that state in nature is incorrect. It is misleading to suggest that this definition of welfare is a functional one rather than one that refers to suffering and other feelings because feelings are a part of animal functioning. Assessment of welfare must take account of the wide variety of coping systems and coping strategies used. A range of measures of behaviour, physiology, brain function, immune system function, damage, strengths of preferences, etc. is needed. The ease or difficulty of coping should be interpreted within the framework of the abilities and needs of the animal. Ethical decisions about animal welfare generally involve a deontological approach, specifying actions that should never be taken, and a consequentialist approach in which costs and benefits are balanced but neither of these approaches is adequate by itself.
ARBS Annu Rev Biomed Sci 2008;10:T79-T90