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Ethics of Research involving animals

The capacity of animals to experience pain, distress and suffering

Introduction

4.1 We have established that the question of the nature of any pain, suffering or distress that an animal might experience in scientific procedures is crucial when assessing the ethical implications of animal research. Many respondents to the Consultation also stressed the importance of taking animal welfare into account:
‘The acceptability depends on the purpose and the amount of suffering for the animals.’
Professor Vera Baumans
‘Our ethical concerns should be geared to the animal’s level of sentience.’
Dr Chris Jackson
‘…there is little real effort to even begin to understand animal pain, distress and suffering, to identify what these terms describe or should describe… and then to address what we need to do to eliminate such states.’ Animal Research Issues Section of The Humane Society of the United States Determining whether sufficient efforts are being made to understand animal welfare is beyond the scope of this Report. However, we note that a number of organisations are already active in the field and have produced a considerable body of knowledge (see Box 2.4). In this chapter we summarise some of the important themes in the current debate about the capacity of animals to experience pain and suffering. We also address difficult conceptual and practical issues that arise when assessing the welfare of animals.

4.2 Common sense and empathy often appear to provide us with clear insight as to whether or not an animal is in a state of pain, suffering or distress. For example, even if we have not previously studied the behaviour of animals in a systematic way, it may be easy to assume that it is in great pain when it tries to escape, or when it makes sounds or facial expressions that are similar to those made by humans experiencing extreme pain. But these approaches have limitations, and it can be difficult to surmise what an animal is experiencing when observing more subtle behaviours. We may observe an animal’s reactions to a stimulus, but are they indicative of pain as we understand the concept when we ascribe it to humans? And is it not more relevant to assess the welfare of laboratory animals in relation to the physiological and behavioural needs that are specific to the species, rather than trying to identify welfare states that are comparable to human pain and suffering? In this chapter, we explore these and other issues in more detail, seeking to address in particular the following questions:

• What is the biological function of pain, suffering and related states in animals and humans?

• Philosophically, and practically, can we ever assess with full certainty whether or not ananimal is in a state of pain, suffering or distress? What are the scope and limitations of empathy, and objective scientific methods when assessing animal welfare?

• Can concepts such as pain, harm, distress and suffering, which are usually applied to humans, be applied in a meaningful way to all animals used for research? Are there some animals for which the identification of such states and the assessment of welfare are more difficult than for others?

• Which other aspects, apart from the experiment itself, need to be considered, when assessing the welfare of animals used in research?

Box 4.1: Concepts relating to the assessment of welfare of animals In discussing problems that arise when assessing the welfare of animals, we use the following terms, unless indicated otherwise: Nociception: The registration, transmission and processing of harmful stimuli by the nervous system.* Pain: ‘An unpleasant sensory and emotional experience associated with actual or potential tissue damage’.† Suffering: ‘A negative emotional state which derives from adverse physical, physiological and psychological circumstances, in accordance with the cognitivecapacity of the species and of the individual being, and its life’s experience.’‡ Distress: Severe pain, sorrow or anguish.∫ ‘Pain, suffering, distress and lasting harm’ in the Guidance on the Operation of the A(SP)A: ‘encompass any material disturbance to normal health (defined as the physical, mental and social well-being of the animal). They include disease, injury and physiological or psychological discomfort, whether immediately (such as at the time of an injection) or in the longer term (such as the consequences of the application of a carcinogen). Regulated procedures may be acts of commission (such as dosing or sampling) or of deliberate omission (such as withholding food or water).’ Sentient: ‘Having the power of perception by the senses’.** Usually taken to mean ‘being conscious’. Welfare/well-being: These terms do not have sharp boundaries. The following statements are indicative of the ways in which they are commonly used: - Animals experience both positive and negative well-being. In assessing welfare, it is important to examine the animal’s physiological and psychological well-being in relation to its cognitive capacity and its life experience. - Welfare is an animal’s perspective on the net balance between positive (reward, satisfaction) and negative (acute stress) experiences of affective states.†† - The welfare of any animal is dependent on the overall combination of various factors which contribute to both its physical and mental state. ‡‡ - Welfare is the state of well-being brought about by meeting the physical, environmental, nutritional, behavioural and social needs of the animal or groups of animals under the care, supervision or influence of individuals.∫∫ College of Medicine and Veterinary Medicine, University of Edinburgh Guidelines for the recognition and assessment of animal pain, available at: http://www.vet.ed.ac.uk/animalpain/Pages/glossary.htm. Accessed on: 11 Apr 2005. † International Association for the Study of Pain (1994) Pain Terminology available at: http://www.iasppain. org/terms-p.html#Pain. Accessed on: 11 Apr 2005. ‡ Morton DB and Hau J (2002) Welfare assessment and humane endpoints, in Handbook of Laboratory Animal Science: Essential principles and practices, Vol I, 2nd Edition, Hau J and Van Hoosier GL (Editors) (Seattle, WA: CRC Press), Chapter 18, pp457–86. ∫ J Pearsall and B Trumble (Editors) (2003) Oxford English Reference Dictionary 2nd Edition (Oxford: Oxford University Press). ** J Pearsall and B Trumble (Editors) (2003) Oxford English Reference Dictionary 2nd Edition (Oxford: Oxford University Press). †† Ethology & Welfare Centre, Faculty of Veterinary Medicine, Utrecht University (2004) What we think, available at: http://www.icwd.nl/think.html. Accessed on: 11 Apr 2005. ‡‡ Department for the Environment, Food and Rural Affairs (2004) Animal Health and Welfare Strategy for Great Britain (London: DEFRA), p16. ∫∫ Appleby MC and Hughes BO (Editors) (1997) Animal Welfare (Wallingford: CABI Publishing).