Each species shows pain in different ways. Dogs may yelp and we'd notice a
behavioural change, but prey species are unlikely to advertise vulnerability to
predators. To treat pain effectively we must be able to measure it - so there's
now a global effort to raise awareness and understanding of pain in animals
07 July 2015
Pain is a complex experience involving sensory and emotional components: it
is not just about how it feels, but also how it makes you feel. And it is these
unpleasant feelings that cause the suffering we humans associate with pain.
The science of suffering is well documented in
the book of the same name by Patrick Wall. We know that animals certainly
feel physical pain, but what is less clear is whether this emotional suffering
that we feel can be said to be true of animals. And if it is, how we go about
As a subjective emotion, pain can be experienced even in the absence of
physical tissue damage, and the level of feeling
can be modified by other emotions including fear, memory and stress. Pain
also has different dimensions -- it is often described in terms of intensity but
it also has "character", for example the pain of a pin-prick is very different
from that of a toothache, a slipped disc or labour pain. Nearly all of us have
experienced pain in our lives, but for each person, the experience is uniquely
To understand or appreciate others' pain we mostly
rely on what they report. But there are many who either cannot communicate
their pain verbally, babies for example, or effectively, like those with
dementia or learning disabilities. In these situations, others must use a
range of factors to judge the presence of pain and its impact on the individual.
Pain is not all bad -- it serves a protective function, to keep us away from
further danger, to help us heal, for example by stopping us from putting weight
on a sprained ankle. But if it isn’t managed effectively it can have a major
negative impact on our lives inducing fear, anger, anxiety or depression -- all
emotions which may in turn exacerbate it. And chronic pain
is a major concern to millions of individuals and to our societies around
Pain in animals
nature of pain is perhaps even more complex in animals. How pain is sensed
and the physical processes behind this are remarkably similar and well conserved
across mammals and humans. There are also many similarities in pain behaviours
across the species, for example they may stop socialising with people and/or
other animals, they may eat less, they may vocalise more and their heart rate
may rise. The capacity of animals to suffer as sentient creatures is well
established and enshrined in law in many countries, however we don’t understand
well how they actually
Some aspects of the experience and expression of pain are not likely to be
the same as in humans. First, animals cannot verbally communicate their pain.
Dogs may yelp and you may notice behaviour change but what about your pet
rabbit, cat, tortoise or horse? Animals rely on human observers to recognise
pain and to evaluate its severity and impact. Without the ability to understand
soothing words that explain that following surgery to repair a bone fracture,
their pain will be managed (hopefully) and will subside, animals may also suffer
more when in pain than we do.
The debate around
capacity to experience pain and suffer raged in the 20th century, but as we
developed a greater understanding of pain, and studied its impact on the aspects
of animal life that we could measure, we veterinary surgeons, along with many
behavioural and animal scientists, recognised the significant impact of
untreated pain, and we now believe this experience causes them to suffer.
For example, we know that animals and indeed birds with clinical signs of pain
(limping) will choose to
eat food containing pain-killing drugs (analgesics) over untreated food, and
by measures of behaviour,
they will improve.
Similarly many studies in a range of domestic animals have indicated that
animals who have had surgery but not had adequate pain relief demonstrate
behaviours reflective of pain
which are alleviated
when they are treated with analgesics such as morphine.
We also know that it is not just our dogs and cats that can suffer pain -- there
is an equally strong evidence base for the presence and negative impact of pain
horses among other
species. But recognising pain in these different species is part of the
complexity associated with animal pain. Managing it in animals that we
rear for food and those that we keep as companions is equally challenging.
Behavioural disturbances have long been recognised as potential indicators of
the presence of pain in animals. However it is important to recognise that each
species manifests its own sometimes unique pain-related behaviours or
behavioural disturbances in different ways, often rooted in the evolutionary
process, so prey species, for example, are less likely to "advertise" an
increased vulnerability to predators. Dogs may become aggressive, or quiet, or
may stop socialising with "their" humans and other dogs. Sheep, on the other
hand, may appear largely the same when casually observed.
Some expressions of pain however may be conserved. A recent paper
suggested commonality in some features of facial expression during acute
pain experiences in several animal species and humans.
These findings and much other work are being incorporated into tools to evaluate
animal pain, because in the words of Lord Kelvin, the great Glaswegian scientist
behind the Kelvin temperature scale, said: "When you cannot measure it, when you
cannot express it in number … you have scarcely, in your thoughts, advanced to
the stage of science, whatever the matter may be".
So in order to treat and manage pain effectively we must measure it.
And there is a huge demand for these tools. The
Glasgow Composite Pain Scale, a
simple tool to measure acute pain in dogs and first published in 2007, has been
translated into six languages. It is used in veterinary practices to measure
pain to treat it effectively. It has also been used to evaluate the
effectiveness of new analgesic drugs that are being developed by animal health
companies. Tools to measure the impact of chronic pain, such as osteoarthritis,
on the quality of life of dogs
are now available and
are a significant advance in managing chronic conditions.
There is now a global effort to raise awareness of pain in animals. Recently the
World Small Animal Veterinary Association
Global Pain Council and published
treatise for vets and animal keepers worldwide to promote pain recognition,
measurement and treatment. Dogs may be man’s best friend, but for all those who
work with, care for and enjoy the company of animals, understanding how their
pain feels is essential to improving the quality of their lives.