Pain Assessment in Lab Animals
The assessment and management of pain in humans and
animals has generated unprecedented discussion in the last
20 years. In the veterinary field, heightened awareness to
pain has prompted several professional organizations to make
formal position statements, which unequivocally mandate pain
relief (McMillan, 2003). Regulatory bodies primarily
concerned with the use of animals in biomedical research and
teaching have also had an increased interest in pain and on
July 10, 2003 the USDA's Animal and Plant Health Inspection
Service (APHIS) published a Federal Register notice calling
for comments on the definition and reporting of pain and
distress in animals under the Animal Welfare Act. While
there is much discussion on the continuum of stress,
distress and pain in animals, there is little agreement on
the difficulty of delineating crossover points for these
apparently overlapping sensations. In addition, there is no
agreed objective measure, which can be used to reliably
identify pain in animals and its severity. Further and more
difficult, is the assessment of different types of pain. For
example, while there is an intuitive predilection to
consider “real” pain as physical pain, several studies
suggest psychological distress can also adversely affect
animal welfare (McMillan, 2003).
Semantics aside, it is generally agreed that pain
adversely impacts the welfare of animals and that in
research protocols, pain, if not controlled, is a variable,
which can confound the interpretation of experimental
results. A position statement of the American College of
Laboratory Animal Medicine (ACLAM) declares that "Procedures
expected to cause more than slight or momentary pain (e.g.,
pain in excess of a needle prick or injection) require the
appropriate use of pain-relieving measures unless
scientifically justified in an approved animal care and use
protocol."
The responsibility to relieve pain in animals used in
research is consistent with the generally accepted view of
the moral responsibility of humans towards animals; with the
opinion of the public, whose support for the use of animals
in research declines as the pain experienced by these
animals increases (Institute for Laboratory Animal Research,
2000); with relevant legislation (AWA, PHS) and with the
goals of scientific research.
This paper presents an overview of current concepts of
pain and provides recommendations for the assessment,
prevention and treatment of pain in rodents and rabbits.
Also provided are guidelines for developing pain management
protocols, tables describing the potential physiologic
effects of some analgesic classes and examples of
efficacious analgesic strategies.
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