As described in the report, Recognition and Alleviation of Pain in Laboratory Animals (2009), there are some situations in which animal pain
is unavoidable, such as when pain is a tool to motivate
or shape behavior, or when pain is the focus of
research. The ethical justification for such research
should consider both the costs to the animal and the
anticipated benefits of the research to humans and
animals: the greater the cost to the research animals,
the stronger the scientific and ethical justification of
the research should be.
Laws and regulations require that investigators
adequately control pain in research animals, unless
the outcomes of an experiment would be negatively
impacted. Alleviating pain in research animals typically
refers to reducing its duration and/or intensity,
as those two characteristics affect aversiveness.
Pain alleviation strategies may include preventative
measures, therapeutic measures, or a combination
of the two.
Preventative Measures
Preventative measures include appropriate
animal handling and restraint, minimization of tissue
trauma during surgery, the use of minimally invasive
surgery techniques (such as fiberoptic technologies),
and other non-pharmacological methods. The "Three Rs" provide the underlying principle to the ethical care and use
of laboratory animals.
Therapeutic Measures
Therapeutic measures include the use of general
and local anesthetics, sedatives
or drugs that relieve anxiety, and analgesics.
- General anesthesia: Animals are anesthetized
(completely numbed) in order to undertake procedures
that would otherwise cause pain.
- Sedation/anxiety relief: These drugs are often
used in combination or with general anesthetics to
modulate, block, or relieve pain.
- Analgesia: These reduce pain locally or temporarily.
Although analgesia is defined as "lack of pain,"
complete elimination of pain in awake animals is
commonly neither achievable nor desirable (the
ability to feel some pain prevents an animal from
further damaging an injured area, for example).
Pain management goals
range from total elimination of pain as, for example,
during general anesthesia for a surgical procedure,
to pain that is tolerated without compromising the
animal's well-being. The
full report provides reference
tables to inform which approaches laboratory personell
should consider in circumstances of low, medium,
and high levels of pain, as well as tables outlining the
properties of various classes of drugs and when to use
them.
The "Three Rs"
The "Three Rs" provide the underlying principle to the ethical care and use
of laboratory animals:
- Refinement of experimental procedures to reduce or eliminate pain and distress.
Where the use of animals is unavoidable, minimize pain, distress, lasting
harm, or other threats to animal welfare. For example, researchers should ensure
that accommodation meets animals' needs; use pain treatment drugs; and
specify humane endpoints—that is, when a study design should be changed or
a study ended early due to concerns about animal pain, distress, or welfare.
-
Reduction in the number of animals being used. Use methods that enable
equivalent information to be obtained from fewer animals or more information
from the same number of animals, such as through the use of advanced imaging
techniques.
- Replacement of animals with other reliable models. For example, use alternative
methodologies, such as computer modeling, or replace higher order
animals with those of a lower order (such as using amphibians or invertebrates
instead of mammals).
