Ethics of Research involving animals
Evaluation of clinical signs
4.19 Clinical signs of adverse effects on welfare take a wide range of forms. At one end of the spectrum, animals may seek vigorously and repeatedly to escape from cages, or they may resist vehemently being handled in certain ways. There are other, less obvious signs, such as changes in biological features including food and water consumption, body weight, levels of hormones and glucose, adrenal gland mass, or species-specific appearance, posture and behaviour.16 Measures of these changes are generally used in conjunction with one another to provide a basis for assessing stress, since, for example, elevated levels in the blood of a hormone called cortisol (a ‘stress hormone’) is a reliable indicator of stress as well as a response to more positive circumstances.
4.20 Clinical signs such as body weight and temperature, respiration and heart rates can be measured in objective ways. Others, such as the quality of respiration (deep, shallow, laboured), posture, appearance (closed eyes, ruffled coats, fur or feathers), diarrhoea, coughing and convulsions are more difficult to quantify. Nonetheless, in veterinary clinical practice, it is possible to grade them in a standardised way. For example, an animal may be ‘hopping lame’, or bear some weight and be limping. More formal and defined assessments of clinical signs, normal behaviours and particularly abnormal behaviours also enable more objective measurements of pain and suffering.
4.21 Trained personnel can gain a significant amount of information about an animal’s wellbeing through evaluation of a set of clinical observations.17 These include measurement of physiological parameters relevant to the species and situation, and awareness of the animal’s behavioural responses to pain and suffering. While valid and verifiable quantifiable data are necessary for making reliable welfare assessments, they are not sufficient. No single sign, whether seen as subjective or objective, can directly inform a researcher, veterinarian or animal technician about the general disposition of an animal. A number of different parameters need to be integrated with the more subjective observations to achieve a meaningful evaluation.
Footnotes16 See Moberg G and Mench JA (Editors) (2000) The Biology of Animal Stress, Basic principles and implications for animal welfare
(Wallingford: CABI Publishing).
17 See Rutherford M (2002) Assessing pain in animals Anim Welfare 11: 31–53; Paul-Murphy J, Ludders JW, Robertson SA et al.
(2004) The need for a cross-species approach to the study of pain in animals J Am Vet Med Assoc 224: 692–7; Bateson P (1991)
Assessment of pain in animals Anim Behav 42: 827–39.
18 Dawkins MS (1980) Animal Suffering: The Science of Animal Welfare (London: Chapman and Hall).