Ethics of Research involving animals
Ethological and ecological data
4.23 We said above that suffering can be defined as: ‘a negative emotional state which derives from adverse physical, physiological and psychological circumstances, in accordance with the cognitive capacity of the species and of the individual being, and its life’s experience.’ In the second part of the sentence, the definition refers to the welfare ‘of the species and of the individual’, which raises issues that require further discussion. The two previous approaches focused on monitoring of clinical signs and the choices of individual animals kept in laboratory environments. To assess well-being more comprehensively, it is also important to be familiar with the way in which particular species behave in their natural environment.
4.24 Ethology is the scientific study of animal behaviour. A range of different ways of quantifying, measuring and documenting animal behaviour have been developed. Animal ecology refers to the scientific study of the relations of organisms to one other and to their physical surroundings. Both fields of study make useful contributions to the assessment of animal welfare. First, they can help to identify suitable (and unsuitable) environments in which animals might be kept under laboratory conditions. Secondly, awareness of an animal’s natural behaviour can be useful to identify states of well-being or stress (see paragraph 4.22).
4.25 However, as we have said (paragraphs 3.41–3.43), there is disagreement about the importance of comparisons with an animal’s natural environment. Defining a natural environment is not straightforward. For example, mice and rats not only live in natural habitats such as forests or meadows, but also in urban environments. These animals are highly adaptable and this ability may bring into question the need for the study of behaviour in their ‘natural’ habitats. In addition, nearly all of the laboratory animals used in research in the UK have been bred for the purpose.19 Some researchers therefore argue that the behaviour of these animals in natural environments is simply not relevant, and that they will not miss any features that they have not known in the laboratory environment.
4.26 These arguments are problematic. For example, it was recently reported that laboratory-bred rats can rapidly adapt to a more natural environment when released into a large outdoor enclosure. The rats were able to perform behaviours that the laboratory environment prevents, for example, digging and climbing (see paragraphs 4.37–4.42).20 Furthermore, while many animals can live in a range of different environments, there are also limits to their ability to adapt. Unsuitable environments may cause stress because most animals will seek to exhibit intrinsic behaviours. If the environmental constraints are very strong, animals may fail to adapt and even die.
If the constraints are less severe, they may still cause stress that may be evidence by stereotypic behaviour (Box 4.3). For example, it would not be desirable to confine dogs, which are members of a roaming species, to very small pens. Similarly, primates and rats are social animals and, in their natural environment, live in groups. Keeping them in compatible, stable groups is therefore preferable to keeping them housed singly.21 It is also important to most animals that they are allowed to forage for food, rather than obtaining it from a bowl or dispenser. Familiarity with species-specific needs can therefore allow people who handle and work with laboratory animals to assess more easily whether environments are likely to constrain or support the welfare of individual animals.
| Box 4.3: Stereotypic behaviours Some animals in captivity exhibit ‘stereotypic behaviours’. These are defined as repetitive, unvarying behaviours that appear to have no goal or function, such as recurring and excessive gnawing, pacing, circling or jumping. Animals tend to develop stereotypies as a result of an inadequate environment, stress, frustration or a reduction in social interactions.* * Rodent Refinement Working Party (1998) Refining rodent husbandry: the mouse Lab Anim 32: 233–59. |
Consideration of physiological and neurological features
4.27 We are familiar with the consequences of manipulating pain pathways in ourselves through subjective experience and methodological inquiry. It is therefore reasonable to assume that animals with very similar physiological structures experience similar states of pain, suffering and distress (paragraphs 4.16–4.17). But assessments become more difficult for animals that are less similar to humans, particularly if they live in different environments. Evolution has produced a range of adaptive solutions to environmental challenges. For example, flight has been resolved in several different ways in insects, bats and birds. Similarly, it is plausible to assume that the principal function of pain as a ‘special-purpose damage-avoidance system’ has been realised in a variety of ways across different species.22 For example, insects such as the fruit fly have pain receptors but no nervous system equivalent to the pain pathways in mammals.23 Nonetheless they have complex nervous systems hat enable them to associate odours with electrical shocks, prompting them to avoid such odours on subsequent occasions.24 Similarly, the common octopus (Octopus vulgaris), which was included in the A(SP)A in 1993, does not have similar neurological pathways to humans, but is able to associate visual and tactile stimuli with electrical shocks.25 The octopus also possesses chemoreceptors that allow the detection of substances at very low concentrations.26
4.28 Empirical research has sought to assess the functioning of nervous systems in such animals and to determine whether they are capable of experiencing pain or suffering in ways to which we can relate. At the same time, the fact that humans and some other animals possess nociceptors and a system of neural pathways does not in itself prove that there are no other ways of producing conscious experience. While physiological and neurological analogies in animals may therefore be useful indicators of comparable experiences, the absence of analogous structures cannot necessarily be taken to mean that they are incapable of experiencing pain, suffering or distress or any other higher-order states of conscious experience.27
Footnotes19 Most animals used in research in the UK, except farm animals, must only be obtained from designated breeding or supplying
establishments (see paragraph 13.24).
20 The Laboratory Rat: A Natural History, available at: http://www.ratlife.org/. Accessed on: 20 Apr 2005.
21 Note that the use of wild-caught primates is banned in the UK under the A(SP)A, except where exceptionally and specifically
justified.
22 Bateson P (1991) Assessment of pain in animals Anim Behav 42: 827–39.
23 However, there is evidence that some insects likely experience pain. See Bekoff M (Editor) Encyclopedia of Animal Rights and Animal Welfare (Westport: Greenwood Publishing Group); Bekoff M (Editor) The Smile of a Dolphin: Remarkable Accounts of Animal Emotions (Washington, DC.: Random House/Discovery Books).