97
Laboratory Animals (1990) 24, 97-130
The assessment and control of the severity of scientific procedures on laboratory animals REPORT OF THE LABORATORY ANIMAL SCIENCE ASSOCIATION WORKING PARTY (Assessment and control of severity)
Contents
Pages
Section I
Assessment of the severity of scientific procedures
.
99
Section II
Control of the severity of scientific procedures
.
105
Section III
.Sensitivity of tissues and organs to challenge
.
112
Section IV
Recognition and assessment of the signs of pain and distress in laboratory rodents and rabbits .
115
Appendix References .....
127 '. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Acknowledgments
130 130
Members of the Working Party are: J Wallace FIAT (Convenor)
Dr J Sanford BVSc, PhD, FRCVS M W Smith MVSc DTVM C Bioi FI Bioi
K V Spencer BSc
Biological Services, Haddow Laboratories, Institute of Cancer Research, Cotswold Road, Belmont, Surrey SM2 5NG, UK Wyeth Research (UK) Ltd, Huntercombe Lane South, Taplow, Berks SL6 OPH, UK Central Biomedical Services, Addenbrooke's Hospital Site, Hill's Road, Cambridge CB22QL, UK 20 Queensbury Place, London SW7 2DZ, UK
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LASA Working Party
98
Introduction In recent years there has been increasing public and professional interest in the welfare of animals used for the purpose of scientific research. Many sections of society and scientific research are particularly concerned that adequate provision is made for the welfare of laboratory animals and that scientists conduct their studies on animals with care and compassion. This concern has been recognized in the provisions of the Animals (Scientific Procedures) Act 1986 which, by the issue of licences and certificates, exercises control over the breeding, care and use of vertebrate laboratory animals. Specific conditions attached to both project and personal Iicences control the severity of procedures and limit the amount of pain or discomfort an animal may experience. Holders of project and personal Iicences are expected to be familiar with the signs of pain, discomfort or distress in the species of animal used within a scientific project and to exercise continuous control over the severity of procedures. The degree of severity experienced by an animal shall be the minimum consistent with the successful outcome of a procedure and a termination clause is imposed. To meet these requirements those intending to keep or use animals for scientific procedures will need to develop and implement policies for the control of the severity of the adverse effects of scientific procedures on laboratory animals. The problems surrounding the assessment, recognition, and control of the adverse effects of scientific procedures on animals are complex and the answers are not readily available. As yet, no objective scale has been devised to quantify pain or discomfort in man, or in animals. The difficulties are increased when small animals such as laboratory rodents or rabbits are involved. A questionnaire, on categorizing the signs of pain in laboratory animals, was circulated by the Laboratory Animal Science Association. The
response to this questionnaire indicated that many workers in the field experienced difficulty with the recognition and assessment of pain or discomfort in small rodents by clinical signs alone. This working party was convened by the Laboratory Animals Science Association to consider the problems associated with the recognition and assessment of pain and distress in laboratory animals and how best they might be addressed. Other publications, Morton and Griffiths (1985) and the report of the Association of Veterinary Teachers and Research Workers (1989), have considered the problems of pain and discomfort in laboratory and other animals, mainly from a clinical viewpoint. Barclay et al. (1988) described an index of disturbance to the exploratory behaviour of rats and mice linked to scientific procedures. In addition to offering guidance on the signs of pain and distress in laboratory rodents and rabbits our contribution is intended to direct attention to means by which the severity of the adverse effects of scientific procedures in small laboratory animals can be assessedand controlled. Significant progress is possible in the control of pain and discomfort in laboratory animals if scientists are aware of the possible causes of severity and how it may be assessed and controlled. This report is directed, in the main, towards holders of personal and project licences to assist them in meeting the needs of the animals and requirements of the Animals (Scientific Procedures) Act 1986. The welfare of laboratory animals is of widespread interest and we hope this report will make some positive contribution to this field. (Convenor)
Downloaded from lan.sagepub.com at WEST VIRGINIA UNIV HEALTH on March 11, 2015
James Wallace December 1989
Assessment and control of severity
99
SECTION I Assessment of the severity of scientific procedures The 1986 Act requires that the adverse effects of scientific procedures are categorized and described as being of either mild, moderate or substantial severity. The Home Office Guidance on the operation of the Animals (Scientific Procedures) Act 1986 (Home Office, 1986) provides a definition of these terms together with examples of techniques and procedures which fall within the severity bands. While the terms 'mild, moderate, and substantial' do indicate increasing severity they are subjective and closely associated with the use of the Verbal Rating Scale (VRS) used to evaluate clinical pain in man. Verbal Rating Scales use verbal descriptors which are rated and scored to reflect the nature, intensity, and duration of the pain experienced. Use of the terms 'mild, moderate, and substantial' to assess the severity of scientific procedures on animals without a supporting structure and scale is of limited value at operational level. If a uniform approach is to be made in the assessment and control of the severity of scientific procedures on animals at an operational level it is necessary to examine ways by which severity can be assessed and scored objectively. Definitions of severity Under the terms of the 1986Act 'pain, suffering, distress and lasting harm' are to be interpreted in their widest sense and to include: death, disease, injury, physiological or psychological stress, significant discomfort or any disturbance to normal health, whether immediate or in the longer term. From these definitions it is clear that pain is only one of a number of unpleasant sensations or adverse effects which may contribute to the severity of scientific procedures. Implicit in the terms used in the Act to describe severity is the assumption that the severity of a procedure is related to the nature, degree, and duration of any interference with the well-being of an animal.
'Well-being' suggests a healthy, normal, animal occupying an environment which poses no threats and meets all its immediate needs. For the purpose of assessing the severity of scientific procedures well-being can be regarded as encompassing: health, contentment and the satisfaction of social and ethological needs. Similarly, pain, distress, suffering, ill-health, fear, discomfort deprivation, confinement and any other unpleasant condition, sensation or event can be regarded as the antithesis of 'well-being' . The severity of the adverse effects of a procedure are related to: (i) the nature, duration, strength, and frequency of the challenge (ii) the biological systemsinvolved and the consequences for the animal in terms of pain, suffering, distress, discomfort or deprivation, both immediately and in the longer term. (iii) interference with the particular needs of an individual animal or species (iv) circumstances prevailing at the time of the challenge. In the assessment of the severity of procedures the cumulative effect of particular techniques should be taken into account. Repeated applications of a challenge may increase severity. Although it is not possible to be certain of all the needs of an individual animal or species, it is evident that certain requirements are fundamental to the survival and well-being of man and many mammals. Interference with basic physiological functions or needs present a greater risk to well-being or survival than interference with behavioural requirements (Maslow, 1970; Curtis, 1985). ASSESSMENT OF SEVERITY
Assessing the adverse effects of procedures in terms of pain, distress or discomfort and in species far removed from man presents immediate difficulties.
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LASA Working Party
100
In man, personal experience and the ability to describe verbally the nature of pain, distress and discomfort provides an aid to assessment. In the absence of verbal communication or in subjects with limited cognitive abilities, such as human infants (Eland & Anderson, 1977; McGrath et al. 1985), and in animals, problems arise. The existence of pain, discomfort and distress in animals can only be inferred by observation. A direct anthropomorphic approach to the problem presents immediate difficulties and in practice can lead to the needs of the animals being ignored. Judgements on the nature of pain and discomfort in animals can only be made after acquiring the necessary knowledge and experience. The behavioural and physiological responses of animals to painful stimuli or distressing events are not uniform and vary between individuals and
species. The responses of animals are determined
by evolutionary processes and genetic composition and are modulated by individual experience. In the absence of evidence to the contrary it must be assumed that any stimuli or experience which produces pain or discomfort in man may also be painful and discomforting for animals. This approach should not exclude those experiences or situations which are known to affect the well-being of a particular species. COMPONENTS OF SEVERITY
The adverse effects of scientific procedures arise from two major components: 1. Scientific objective: investigative component of the procedure. The toxicity of a compound, action of a drug or infective agent, modification of behaviour are examples of the scientific component of severity; and 2. Techniques: which are applied to an animal to achieve the scientific objective by modifying, controlling, monitoring biological processes or used to administer a challenge, comprise the technical component.
Scientific component The specialist knowledge of the holder of the project licence in the field of investigation and the specific nature an!l
circumstances of the challenge are essential in evaluating the severity of the adverse effects of the scientific component.
Technical components In some instances, the adverse effects of the techniques may exceed that of the scientific component. Surgical modification of an animal may present a greater risk to life during the procedure and of pain and discomfort afterwards than any action of the investigative component of the procedure. Conversely, a simple injection may administer an agent whose adverse effects exceed those of the technique. Index of severity
Described below is a system for developing an index of severity (SI) for scientific procedures. In this system the components of severity common to many procedures are identified and given a numerical rating refleding a potential range of severity. A procedure is reviewed for the components of severity and each component awarded a score reflecting the adverse effect upon the animal. If restraint of an animal is regarded as contributing to severity and awarded a scale of 4 then, transitory, manual, restraint might incur a score of 1 or none, while continuous, whole body restraint could incur the maximum score. Individual scores for each component are added together to reach an index of severity (SI) for the procedure. The higher the final score the greater the potential severity of the procedure. The numerical ratings and scores awarded to individual components of severity and the SI (severity index) represent interval, not absolute, scales and are intended to indicate a potential range of response and a general increase in severity. On a scale of 5, no score would indicate normality and a score of one minimal disturbance. A score of 5 indicates an increase in severity over a score of 1 but not necessarily by a factor of 5. To reflect a general increase in severity the SI has been linked to three levels of response:
Downloaded from lan.sagepub.com at WEST VIRGINIA UNIV HEALTH on March 11, 2015
Assessment and control of severity
Severity index 20 High The overlap between bands indicates an absence of absolute divisions. IDENTIFYING AND SCORING COMPONENTS OF SEVERITY
The list of components of severity given below is not exhaustive but includes those common to many procedures. Conscious (Scale 1) The animal is conscious throughout procedure. Score should reflect potential for the animal experiencing pain or discomfort. Anaesthesia (Scale 4) This technique involves the use of general anaesthesia either for restraint or analgesia and muscle relaxation. While anaesthetic agents abolish pain, discomfort or distress during a procedure their use is associated with some risk of mortality and unpleasant effects during recovery. The score should reflect the duration and complexity of anaesthesia and potential risk to the animal. Preparation (Scale 2) The procedure or technique requires preparatory manipulation, such as shaving, fasting or training of a conscious animal. These manipulations may not in themselves be painful but may be stressful. Restraint (Scale 4) Most laboratory animals resent restraint whether manual or by close confinement. The score should reflect range from brief manual (1 or no score) to continuous, whole body restraint (4). Duration (Scale 2) Transitory exposure to painful or distressing events or situations may require only minimal adaptive behavioural or physiological responses by an animal. However, procedures which involve lengthy manipulations or continuous challenge can be expected to increase the risk to the animal. During the application of physical,
101
noxious or aversive stimuli the severity of the adverse effects can often be linked directly to the strength and duration of the challenge. Tissue sensitivity (Scale 2) The differing sensitivity of various tissues to noxious stimuli should be recognized when assessing the severity of scientific procedures. The respiratory tract is particularly sensitive to trauma or chemical irritation, distension of the gut is regarded as painful. In mammals and birds the surface of the eye is sensitiveto virtually any form of interference. This subject is dealt with in greater detail in Section III. Organ risk (Scale 2) This procedure involves a particular risk of harm to specific tissues or organ systems. Obtaining blood samples from the orbital-plexus of the eye carries a risk of permanent damage to the eye. Oral gavage carries the risk of accidental introduction of material into the trachea. Mortality (Scale 4) This procedure presents known or predictable risk to the survival of an animal. Most surgical procedures which involve entry into the thoracic or abdominal cavities would be regarded as carrying a risk of mortality. Cardiac puncture with recovery involves a risk of mortality. Pain, distress and deprivation are scored twice. Initially for pain or distress experienced during the procedure and again for any subsequent pain, distress or deprivation which occurs as a consequence of the procedure.
Pain (Scale 5) Procedure is assessed for potential to cause pain using the following criteria: (i) the stimuli if applied to a conscious human would be regarded as painful (ii) challenge produces damage, distension, inflammation or irritation of tissues (iii) application of the challenge produces those physiological and behavioural responses which, in a conscious animal, are normally associated with pain.
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LASA Working Party
102
An assessment of pain should reflect the nature, intensity and duration. For example, a single injection into superficial tissues which resulted in mild, transient discomfort would receive the lowest score. A procedure which resulted in substantial and/or prolonged pain would receive a higher score. The effect of any measures, such as the use of anaesthetics or analgesics, which may reduce either awareness or the intensity or duration of the pain should also be considered. Distress (Scale 5) It is important to distinguish between techniques which result in an animal experiencing distress, those which are painful and those which may cause both pain and distress. Direct observation alone can lead an inexperienced observer to confuse expressions of emotional disturbance with those of pain or discomfort. Animals may vocalize and show extreme behavioural responses to restraint or other manipulations but these are not necessarily linked to pain or discomfort. Experiences or situations which induce conflict, frustration, fear or anxiety are potentially distressing but not painful. Exposure to certain sound levels, thermal or electrical stimuli, chemical irritants may be distressing or both painful and distressing depending upon the characteristics, duration and intensity of the challenge. Restrictions to the intake of food or drinking water are potentially distressing. Manipulations, or the application of substances, to the eyes, feet, nasal passages, respiratory system or by oral gavage are usually distressing to conscious animals even when pain is not involved. Deprivation (Scale 5) Included are those procedures which result in an animal being deprived of normal physiological function or activity, either temporarily or permanently. Many surgical modifications will result in animals experiencing altered physiological function, behaviour or activity. Interference with an animal's sensory organs can result in a reduced repertoire of behaviour
or activity. The use of collars, slings or whole body dressings to restrict activity or protect areas of the body, confinement, social isolation, limitation on normal movement may all result in behavioural deprivation. MUL TIPLE APPLICATIONS
AND FREQUENCY
Numerical values given above and those in the following tables are for the application of the technique on a single occasion. Where a procedure is applied repeatedly and at short intervals the SI should be increased. Multiple applications of challenge can increase the overall severity of a procedure. Techniques which normally cause an animal minimal pain or discomfort can, if repeated frequently and with only limited opportunity for recovery, significantly increase severity. A single injection of an innocuous substance may be regarded as producing minimal discomfort while multiple injections into a single site may produce local tissue sensitivity. This may result in the animal experiencing increased pain or discomfort. Equally if there are extended intervals between the application of techniques then an increase in severity over that of a single application is unlikely. Using the system described above, many techniques commonly applied to laboratory rodents and rabbits have been reviewed and scored for severity. Some comparative examples are illustrated in the table below. A full tabulated list of procedures scored for severity together with a severity index is provided in the Appendix at the end of this report. Topical application of a material to the skin and a single interperitoneal injection provide examples of minimal severity procedures. Although the final index of severity are similar for both procedures the score for individual components of severity are different. The effect of anaesthesia upon the severity of a procedure is shown by comparing the SI for the collection of blood from the orbital plexus in conscious and anaesthetized animals. Parabiosis is shown as an example of a severe procedure which results in
Downloaded from lan.sagepub.com at WEST VIRGINIA UNIV HEALTH on March 11, 2015
103
Assessment and control of severity
is"' I I
--
-
"
Laboratory Animals (1990) 24, 97-130
The assessment and control of the severity of scientific procedures on laboratory animals REPORT OF THE LABORATORY ANIMAL SCIENCE ASSOCIATION WORKING PARTY (Assessment and control of severity)
Contents
Pages
Section I
Assessment of the severity of scientific procedures
.
99
Section II
Control of the severity of scientific procedures
.
105
Section III
.Sensitivity of tissues and organs to challenge
.
112
Section IV
Recognition and assessment of the signs of pain and distress in laboratory rodents and rabbits .
115
Appendix References .....
127 '. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Acknowledgments
130 130
Members of the Working Party are: J Wallace FIAT (Convenor)
Dr J Sanford BVSc, PhD, FRCVS M W Smith MVSc DTVM C Bioi FI Bioi
K V Spencer BSc
Biological Services, Haddow Laboratories, Institute of Cancer Research, Cotswold Road, Belmont, Surrey SM2 5NG, UK Wyeth Research (UK) Ltd, Huntercombe Lane South, Taplow, Berks SL6 OPH, UK Central Biomedical Services, Addenbrooke's Hospital Site, Hill's Road, Cambridge CB22QL, UK 20 Queensbury Place, London SW7 2DZ, UK
Downloaded from lan.sagepub.com at WEST VIRGINIA UNIV HEALTH on March 11, 2015
LASA Working Party
98
Introduction In recent years there has been increasing public and professional interest in the welfare of animals used for the purpose of scientific research. Many sections of society and scientific research are particularly concerned that adequate provision is made for the welfare of laboratory animals and that scientists conduct their studies on animals with care and compassion. This concern has been recognized in the provisions of the Animals (Scientific Procedures) Act 1986 which, by the issue of licences and certificates, exercises control over the breeding, care and use of vertebrate laboratory animals. Specific conditions attached to both project and personal Iicences control the severity of procedures and limit the amount of pain or discomfort an animal may experience. Holders of project and personal Iicences are expected to be familiar with the signs of pain, discomfort or distress in the species of animal used within a scientific project and to exercise continuous control over the severity of procedures. The degree of severity experienced by an animal shall be the minimum consistent with the successful outcome of a procedure and a termination clause is imposed. To meet these requirements those intending to keep or use animals for scientific procedures will need to develop and implement policies for the control of the severity of the adverse effects of scientific procedures on laboratory animals. The problems surrounding the assessment, recognition, and control of the adverse effects of scientific procedures on animals are complex and the answers are not readily available. As yet, no objective scale has been devised to quantify pain or discomfort in man, or in animals. The difficulties are increased when small animals such as laboratory rodents or rabbits are involved. A questionnaire, on categorizing the signs of pain in laboratory animals, was circulated by the Laboratory Animal Science Association. The
response to this questionnaire indicated that many workers in the field experienced difficulty with the recognition and assessment of pain or discomfort in small rodents by clinical signs alone. This working party was convened by the Laboratory Animals Science Association to consider the problems associated with the recognition and assessment of pain and distress in laboratory animals and how best they might be addressed. Other publications, Morton and Griffiths (1985) and the report of the Association of Veterinary Teachers and Research Workers (1989), have considered the problems of pain and discomfort in laboratory and other animals, mainly from a clinical viewpoint. Barclay et al. (1988) described an index of disturbance to the exploratory behaviour of rats and mice linked to scientific procedures. In addition to offering guidance on the signs of pain and distress in laboratory rodents and rabbits our contribution is intended to direct attention to means by which the severity of the adverse effects of scientific procedures in small laboratory animals can be assessedand controlled. Significant progress is possible in the control of pain and discomfort in laboratory animals if scientists are aware of the possible causes of severity and how it may be assessed and controlled. This report is directed, in the main, towards holders of personal and project licences to assist them in meeting the needs of the animals and requirements of the Animals (Scientific Procedures) Act 1986. The welfare of laboratory animals is of widespread interest and we hope this report will make some positive contribution to this field. (Convenor)
Downloaded from lan.sagepub.com at WEST VIRGINIA UNIV HEALTH on March 11, 2015
James Wallace December 1989
Assessment and control of severity
99
SECTION I Assessment of the severity of scientific procedures The 1986 Act requires that the adverse effects of scientific procedures are categorized and described as being of either mild, moderate or substantial severity. The Home Office Guidance on the operation of the Animals (Scientific Procedures) Act 1986 (Home Office, 1986) provides a definition of these terms together with examples of techniques and procedures which fall within the severity bands. While the terms 'mild, moderate, and substantial' do indicate increasing severity they are subjective and closely associated with the use of the Verbal Rating Scale (VRS) used to evaluate clinical pain in man. Verbal Rating Scales use verbal descriptors which are rated and scored to reflect the nature, intensity, and duration of the pain experienced. Use of the terms 'mild, moderate, and substantial' to assess the severity of scientific procedures on animals without a supporting structure and scale is of limited value at operational level. If a uniform approach is to be made in the assessment and control of the severity of scientific procedures on animals at an operational level it is necessary to examine ways by which severity can be assessed and scored objectively. Definitions of severity Under the terms of the 1986Act 'pain, suffering, distress and lasting harm' are to be interpreted in their widest sense and to include: death, disease, injury, physiological or psychological stress, significant discomfort or any disturbance to normal health, whether immediate or in the longer term. From these definitions it is clear that pain is only one of a number of unpleasant sensations or adverse effects which may contribute to the severity of scientific procedures. Implicit in the terms used in the Act to describe severity is the assumption that the severity of a procedure is related to the nature, degree, and duration of any interference with the well-being of an animal.
'Well-being' suggests a healthy, normal, animal occupying an environment which poses no threats and meets all its immediate needs. For the purpose of assessing the severity of scientific procedures well-being can be regarded as encompassing: health, contentment and the satisfaction of social and ethological needs. Similarly, pain, distress, suffering, ill-health, fear, discomfort deprivation, confinement and any other unpleasant condition, sensation or event can be regarded as the antithesis of 'well-being' . The severity of the adverse effects of a procedure are related to: (i) the nature, duration, strength, and frequency of the challenge (ii) the biological systemsinvolved and the consequences for the animal in terms of pain, suffering, distress, discomfort or deprivation, both immediately and in the longer term. (iii) interference with the particular needs of an individual animal or species (iv) circumstances prevailing at the time of the challenge. In the assessment of the severity of procedures the cumulative effect of particular techniques should be taken into account. Repeated applications of a challenge may increase severity. Although it is not possible to be certain of all the needs of an individual animal or species, it is evident that certain requirements are fundamental to the survival and well-being of man and many mammals. Interference with basic physiological functions or needs present a greater risk to well-being or survival than interference with behavioural requirements (Maslow, 1970; Curtis, 1985). ASSESSMENT OF SEVERITY
Assessing the adverse effects of procedures in terms of pain, distress or discomfort and in species far removed from man presents immediate difficulties.
Downloaded from lan.sagepub.com at WEST VIRGINIA UNIV HEALTH on March 11, 2015
LASA Working Party
100
In man, personal experience and the ability to describe verbally the nature of pain, distress and discomfort provides an aid to assessment. In the absence of verbal communication or in subjects with limited cognitive abilities, such as human infants (Eland & Anderson, 1977; McGrath et al. 1985), and in animals, problems arise. The existence of pain, discomfort and distress in animals can only be inferred by observation. A direct anthropomorphic approach to the problem presents immediate difficulties and in practice can lead to the needs of the animals being ignored. Judgements on the nature of pain and discomfort in animals can only be made after acquiring the necessary knowledge and experience. The behavioural and physiological responses of animals to painful stimuli or distressing events are not uniform and vary between individuals and
species. The responses of animals are determined
by evolutionary processes and genetic composition and are modulated by individual experience. In the absence of evidence to the contrary it must be assumed that any stimuli or experience which produces pain or discomfort in man may also be painful and discomforting for animals. This approach should not exclude those experiences or situations which are known to affect the well-being of a particular species. COMPONENTS OF SEVERITY
The adverse effects of scientific procedures arise from two major components: 1. Scientific objective: investigative component of the procedure. The toxicity of a compound, action of a drug or infective agent, modification of behaviour are examples of the scientific component of severity; and 2. Techniques: which are applied to an animal to achieve the scientific objective by modifying, controlling, monitoring biological processes or used to administer a challenge, comprise the technical component.
Scientific component The specialist knowledge of the holder of the project licence in the field of investigation and the specific nature an!l
circumstances of the challenge are essential in evaluating the severity of the adverse effects of the scientific component.
Technical components In some instances, the adverse effects of the techniques may exceed that of the scientific component. Surgical modification of an animal may present a greater risk to life during the procedure and of pain and discomfort afterwards than any action of the investigative component of the procedure. Conversely, a simple injection may administer an agent whose adverse effects exceed those of the technique. Index of severity
Described below is a system for developing an index of severity (SI) for scientific procedures. In this system the components of severity common to many procedures are identified and given a numerical rating refleding a potential range of severity. A procedure is reviewed for the components of severity and each component awarded a score reflecting the adverse effect upon the animal. If restraint of an animal is regarded as contributing to severity and awarded a scale of 4 then, transitory, manual, restraint might incur a score of 1 or none, while continuous, whole body restraint could incur the maximum score. Individual scores for each component are added together to reach an index of severity (SI) for the procedure. The higher the final score the greater the potential severity of the procedure. The numerical ratings and scores awarded to individual components of severity and the SI (severity index) represent interval, not absolute, scales and are intended to indicate a potential range of response and a general increase in severity. On a scale of 5, no score would indicate normality and a score of one minimal disturbance. A score of 5 indicates an increase in severity over a score of 1 but not necessarily by a factor of 5. To reflect a general increase in severity the SI has been linked to three levels of response:
Downloaded from lan.sagepub.com at WEST VIRGINIA UNIV HEALTH on March 11, 2015
Assessment and control of severity
Severity index 20 High The overlap between bands indicates an absence of absolute divisions. IDENTIFYING AND SCORING COMPONENTS OF SEVERITY
The list of components of severity given below is not exhaustive but includes those common to many procedures. Conscious (Scale 1) The animal is conscious throughout procedure. Score should reflect potential for the animal experiencing pain or discomfort. Anaesthesia (Scale 4) This technique involves the use of general anaesthesia either for restraint or analgesia and muscle relaxation. While anaesthetic agents abolish pain, discomfort or distress during a procedure their use is associated with some risk of mortality and unpleasant effects during recovery. The score should reflect the duration and complexity of anaesthesia and potential risk to the animal. Preparation (Scale 2) The procedure or technique requires preparatory manipulation, such as shaving, fasting or training of a conscious animal. These manipulations may not in themselves be painful but may be stressful. Restraint (Scale 4) Most laboratory animals resent restraint whether manual or by close confinement. The score should reflect range from brief manual (1 or no score) to continuous, whole body restraint (4). Duration (Scale 2) Transitory exposure to painful or distressing events or situations may require only minimal adaptive behavioural or physiological responses by an animal. However, procedures which involve lengthy manipulations or continuous challenge can be expected to increase the risk to the animal. During the application of physical,
101
noxious or aversive stimuli the severity of the adverse effects can often be linked directly to the strength and duration of the challenge. Tissue sensitivity (Scale 2) The differing sensitivity of various tissues to noxious stimuli should be recognized when assessing the severity of scientific procedures. The respiratory tract is particularly sensitive to trauma or chemical irritation, distension of the gut is regarded as painful. In mammals and birds the surface of the eye is sensitiveto virtually any form of interference. This subject is dealt with in greater detail in Section III. Organ risk (Scale 2) This procedure involves a particular risk of harm to specific tissues or organ systems. Obtaining blood samples from the orbital-plexus of the eye carries a risk of permanent damage to the eye. Oral gavage carries the risk of accidental introduction of material into the trachea. Mortality (Scale 4) This procedure presents known or predictable risk to the survival of an animal. Most surgical procedures which involve entry into the thoracic or abdominal cavities would be regarded as carrying a risk of mortality. Cardiac puncture with recovery involves a risk of mortality. Pain, distress and deprivation are scored twice. Initially for pain or distress experienced during the procedure and again for any subsequent pain, distress or deprivation which occurs as a consequence of the procedure.
Pain (Scale 5) Procedure is assessed for potential to cause pain using the following criteria: (i) the stimuli if applied to a conscious human would be regarded as painful (ii) challenge produces damage, distension, inflammation or irritation of tissues (iii) application of the challenge produces those physiological and behavioural responses which, in a conscious animal, are normally associated with pain.
Downloaded from lan.sagepub.com at WEST VIRGINIA UNIV HEALTH on March 11, 2015
LASA Working Party
102
An assessment of pain should reflect the nature, intensity and duration. For example, a single injection into superficial tissues which resulted in mild, transient discomfort would receive the lowest score. A procedure which resulted in substantial and/or prolonged pain would receive a higher score. The effect of any measures, such as the use of anaesthetics or analgesics, which may reduce either awareness or the intensity or duration of the pain should also be considered. Distress (Scale 5) It is important to distinguish between techniques which result in an animal experiencing distress, those which are painful and those which may cause both pain and distress. Direct observation alone can lead an inexperienced observer to confuse expressions of emotional disturbance with those of pain or discomfort. Animals may vocalize and show extreme behavioural responses to restraint or other manipulations but these are not necessarily linked to pain or discomfort. Experiences or situations which induce conflict, frustration, fear or anxiety are potentially distressing but not painful. Exposure to certain sound levels, thermal or electrical stimuli, chemical irritants may be distressing or both painful and distressing depending upon the characteristics, duration and intensity of the challenge. Restrictions to the intake of food or drinking water are potentially distressing. Manipulations, or the application of substances, to the eyes, feet, nasal passages, respiratory system or by oral gavage are usually distressing to conscious animals even when pain is not involved. Deprivation (Scale 5) Included are those procedures which result in an animal being deprived of normal physiological function or activity, either temporarily or permanently. Many surgical modifications will result in animals experiencing altered physiological function, behaviour or activity. Interference with an animal's sensory organs can result in a reduced repertoire of behaviour
or activity. The use of collars, slings or whole body dressings to restrict activity or protect areas of the body, confinement, social isolation, limitation on normal movement may all result in behavioural deprivation. MUL TIPLE APPLICATIONS
AND FREQUENCY
Numerical values given above and those in the following tables are for the application of the technique on a single occasion. Where a procedure is applied repeatedly and at short intervals the SI should be increased. Multiple applications of challenge can increase the overall severity of a procedure. Techniques which normally cause an animal minimal pain or discomfort can, if repeated frequently and with only limited opportunity for recovery, significantly increase severity. A single injection of an innocuous substance may be regarded as producing minimal discomfort while multiple injections into a single site may produce local tissue sensitivity. This may result in the animal experiencing increased pain or discomfort. Equally if there are extended intervals between the application of techniques then an increase in severity over that of a single application is unlikely. Using the system described above, many techniques commonly applied to laboratory rodents and rabbits have been reviewed and scored for severity. Some comparative examples are illustrated in the table below. A full tabulated list of procedures scored for severity together with a severity index is provided in the Appendix at the end of this report. Topical application of a material to the skin and a single interperitoneal injection provide examples of minimal severity procedures. Although the final index of severity are similar for both procedures the score for individual components of severity are different. The effect of anaesthesia upon the severity of a procedure is shown by comparing the SI for the collection of blood from the orbital plexus in conscious and anaesthetized animals. Parabiosis is shown as an example of a severe procedure which results in
Downloaded from lan.sagepub.com at WEST VIRGINIA UNIV HEALTH on March 11, 2015
103
Assessment and control of severity
is"' I I
--
-
"
![[Animal welfare and the use of laboratory animals in scientific research].](/assets/img/hold.png)
