What is Animal Pain?
PAIN is a word used by humans to represent one of
their experiences. They know what it is without needing to define it.
Animal pain should not be confused with human pain.
However, it is helpful to use definitions of human pain to understand animal
pain. Animal pain probably serves the same purposes as human pain and is as
important to the animal as pain is to humans. However, animal and human
experiences of pain, in response to the same stimulus, may not be identical.
(Human) pain is:
“An unpleasant sensory and emotional experience associated with actual or
potential tissue damage or described in terms of such damage”
(IASP, 1979).
Two
definitions of animal pain are:
-
Pain
in animals is an aversive sensory experience that elicits protective motor
actions, results in learned avoidance and may modify species specific traits of
behaviour, including social behaviour
-
Animal pain is an aversive, sensory experience representing
awareness by the animal of damage or threat to the integrity of its tissues;
(note that there might not be any damage). It changes the animal’s
physiology and behaviour to reduce or avoid the damage, to reduce the likelihood
of its recurrence and to promote recovery. Non-functional (non-useful)
pain occurs when the intensity or duration of the experience is not appropriate
for damage sustained (especially if none exists) and when physiological and
behavioural responses are unsuccessful in alleviating it (Molony,
1997)
Sites of Origin
of Pain:
-
Somatic pain originates
from the body including skin, bone, muscles,
tendons and other tissues.
-
Visceral pain
originates from the internal organs e.g. heart, lungs, alimentary canal and
reproductive organs.
-
Neuropathic pain
originates from nerves, the spinal cord and
brain because of abnormal processing of nervous activity.
The pain from internal organs can be localised to superficial
sites (Referred pain)
Duration
of Pain:
Acute pain immediately follows injury and disappears when the
injury heals. It is usually associated with quantifiable changes to processes
providing the body with protection from damage (defensive body processes).
Chronic
pain is prolonged, however, there is little agreement as to when recurring
bouts of acute pain become chronic pain or for how long pain must persist to be
considered chronic. Quantifiable changes to the functioning of defensive body
processes may NOT be seen.
Chronic inflammatory pain:
occurs when healing persists beyond the expected time, due
to infection or other inflammatory processors.
Chronic neuropathic pain:
may not have a well-defined onset and may not respond to treatments that are
effective against acute or chronic inflammatory
pain. It is sometimes described as "intractable" pain.
