Animal welfare science is a relatively new scientific discipline, evolving mostly
from within veterinary medicine over the latter half of the twentieth century into
an independent specialty in its own right. Originally, the field of study was heavily
focused on animal behavior (ethology), but it has emerged into a truly multi- and
inter-disciplinary science, encompassing such sciences as behavior, physiology, pathology,
health, immunology, endocrinology, and neuroscience, and influenced by personal and
societal ethics. The first academic organization devoted to the scientific study of
animal welfare was established in 1966 as the society for veterinary ethology (SVE),
demonstrating its veterinary roots by being then affiliated with the British Veterinary
Association. The world’s first Professor of Animal Welfare was appointed 20 years
later at the University of Cambridge’s Department of Clinical Veterinary Medicine,
and in 1991, the SVE became the International Society for Applied Ethology, in recognition
of its geographical spread and its evolution from veterinary medicine. Over the last
quarter of a century, there has been further expansion of the field and now animal
welfare science is represented in many universities’ veterinary medicine and animal
science departments across the world. Animal welfare science has become part of the
core curriculum for many veterinary degrees, is a recognized specialty qualification
within the veterinary professions of Europe, USA, and Australia and courses in animal
welfare science as a stand-alone discipline are offered worldwide at Bachelor’s, Master’s,
and Doctorate degree levels. Within research, there have been similar patterns of
expansion and a spread from a heavy focus on farm animal welfare to the welfare of
zoo, laboratory, and companion animals and the impacts of humans on wildlife. There
continue to be studies that compare the welfare of populations within systems, but
there is also more attention given to gaining in-depth knowledge of the welfare of
individual animals, knowing that populations are not homogenous and that individuals
within the same system may be experiencing quite different welfare states. We not
only continue to use “traditional” welfare indicators but also work to develop novel
indicators for use in experimental settings or in the field. As our fundamental knowledge
base increases, we look for increasing application and we respond to challenges that
arise from our own research questions and findings and from societal needs. In this
paper, I will focus on a number of the areas that I see represent Grand Challenges
within our discipline.
Animal Welfare Science in Focus
What I hope to address under this title are the challenges that define how the science
of animal welfare may progress over the next few years. I will present my views of
the challenges and opportunities that welfare assessment presents and how we adapt
and adopt methodologies within animal welfare science to obtain greater understanding,
quantification, and qualification of an animal’s welfare state. Historically, animal
welfare has been defined under one of three over-arching, and intersecting, themes
or approaches. These are biological functioning, “naturalness,” and feelings. The
biological functioning theme of animal welfare enables us to focus on discreet measurable
parameters, such as health indicators, production measures, measures of physiological
functioning, and incidence of behaviors, and combine multiple measures to draw an
overall picture of the welfare of the given animal at the time, or prior to, when
the measures are taken. The “naturalness” theme focuses on the extent to which the
animal is leading, or can lead, a life in which it is free to express its natural
behavioral repertoire, with the idea that an animal being able to experience or fulfill
its inherent nature, will have good welfare. The third theme concerns the feelings,
emotions, or affective states of the animal, with the broad idea that for an animal
to be experiencing good welfare, it should not only be devoid of negative emotions,
such as anxiety or fear, but should also be experiencing positive emotions, such as
pleasure or happiness. As I said above, these themes or approaches do not each exist
in isolation and it is commonly acknowledged that there is a degree of overlap between
them, and that in attempting to best establish the welfare state of an individual,
there should be elements drawn from all three approaches (1).
Animal welfare and emotional states
The emotional states of animals in our care have been increasingly important in research
terms, over the last few years. A Web of Science search combining the terms “animal
welfare” with a number of different terms of emotionality shows a rapid increase in
both publications and citations in the last 10 years (Figure 1). Out of a total of
nearly 1350 publications, 130 focus on positive emotional states, whereas over 1200
address negative emotional states and the most cited paper (which includes open commentary
from 45 other academics) concerns animal suffering (2).
Figure 1
Number of publications and citations of studies that include animal welfare and emotions
over the time period 1985–2014 (Web of Science).
However, the more recent trend is an increasing interest in positive rather than negative
emotional states and a recent review article on measuring positive emotions in animals
in relation to welfare is topping the table in terms of citations per year (3). In
terms of recent experimental work, the most influential studies have been those using
cognitive bias to assess emotional state (4, 5). Other work in this area has included
the use of functional near infrared spectroscopy to assess changes in cortical perfusion
and neuronal activity in the study of mood and emotional reactions (6). There is no
doubt that further adaptation of methods used within cognitive science and behavioral
neuroscience will yield new fundamental insight into animal emotions, and thus its
welfare. An example could be further development of electroencephalogram (EEG), which
although currently used in sleep (7) and euthanasia/slaughter studies (8), may also
yield insight into emotional state (9).
Animal welfare and quality of life
A more recent term and concept that has been used within the companion animal welfare
field is that of quality of life (QoL). The term “Quality of Life” originated within
the human sociological/geographical/medical fields in 1950s and 1960s and within the
human field, depending on context, is taken to encompass such measures as wealth,
physical and social environment, health, and biological functioning. Critically, within
the human medical field, it also incorporates the psychological well-being of the
individual and health-related QoL (HRQoL) is defined as being “subjective and multidimensional,
encompassing physical and occupational function, psychological state, social interaction,
and somatic sensation” (10) and invariably includes self-reporting. Certainly, the
emphasis of human QoL is on affective states in general and positive affective states,
in particular. From an animal perspective, this of course presents problems. QoL for
animals has been defined as encompassing animal welfare and the subjective feelings
of the animal regarding its life, but that it can only be inferred from behavioral,
physiological, and other measures (11). So it would seem that for many animal welfare
scientists, there is a large degree of synonymy between their own working definition
of “animal welfare” and that of “animal QoL,” but there is also some confusion (12).
Although there has been recent use and assessment of QoL in animals – mostly companion
animals – there is certainly a degree of resistance within the broader animal welfare
field to use of the term, either because of the perceived time-span limitations of
its coverage or because of the anthropomorphism and subjectivity associated with a
definition that includes assessment of an animal’s psychological state by indirect
methods. However, there is increasing research focus within our field on indicators
of positive welfare, rather than negative welfare, and on measures of the animal’s
affective state, meaning that as our methods and measures evolve and refine, we may
see a shift toward a concept of animal welfare that is more in line with definitions
of QoL than our current definitions of animal welfare.
Animal welfare assessment in the field
Increasing our fundamental knowledge about an animal’s welfare is part of our remit
as animal welfare scientists. We also have to seek to apply that new-found knowledge
to improve the welfare of animals under our care (13). When assessing animal welfare
within an experimental setting, there is greater focus on the individual animal and
more options in terms of the parameters that can be measured. Out in the “field,”
be it within a farm, zoo, or lab animal facility or with companion animals in homes,
stables, or shelters, there are many more limitations on the types of data that can
be collected and where large facility populations are concerned, there will be focus
on the group rather than on individuals within the group.
The reasons for assessing welfare in the field will differ depending on the setting
and the species. For farm animals, ensuring a certain welfare standard may be tied
to improving productivity and also to marketing of the end product, based on consumer
or retailer demand (14), as seen by the many auditing or quality assurance schemes
that exist for farm animal production. For laboratory animals, there is again a societal
demand for a minimum welfare standard to be met, and there is sound argument that
testing is carried out on animals devoid of poor welfare and altered biological function
(15). For zoo animals, it may be relevant again to the “consumer” – i.e., the zoo-going
public – and enforced by legislation (16), but also to better serve the biological
needs of the animals to facilitate reproduction in those species subject to conservation
efforts and because it is an ethical obligation. The Association of Zoos and Aquariums
has a stated policy that “Animal and human health, safety, and welfare are never compromised”
(17). Welfare assessment among companion animals is less developed and is more focused
on environments where populations are being housed – e.g., humane shelters – rather
than home settings with few individuals. Within shelters, there is an increasing understanding
that physical and social environments that improve welfare also improve long-term
adoptability (18).
The majority of field welfare assessment protocols for farm animals are heavily weighted
in terms of environmental assessment – that is they gather much information on such
things as the physical housing, the management techniques, the health and production
records, and relatively less information on measures that are taken on the animals
themselves. On large farms, there is a trade-off between time and the number of animals
that can be assessed, and thus assessment has to be carried out on a representative
sample, that will give an indication of the overall, or “population average” welfare
rather than the welfare of individuals within the population. Also, the animal-based
measures that are taken are often more concerned with direct measures of health and
disease, or indirect measures of behavior, such as skin lesions, rather than the behavior
itself. There has been some good progress in farm animal assessment recently (19),
but more animal-centered methods and, in particular, methods that give quantifiable
insight into the psychological lives of animals are needed, together with the development
and validation of new indicators, such as tear-staining (20, 21) that are relatively
easily discernable to the observer, that may enable more objective assessment of individuals
within a given population. For laboratory animals, even in a large facility, there
should be greater attention to the individual than seen with on-farm assessment (22).
Welfare assessment should comprise components that describe or quantify physical,
physiological/biochemical, and psychological states, and may include scoring scales
for such things as body weight, coat condition, respiration rates, ocular discharge,
feces condition, and provoked behavioral response. With well-defined scoring scales,
the overall assessment of an individual’s welfare can be objectively quantified and
intervention carried out if a threshold total score is reached (22). Zoo animals are
mostly housed in limited numbers and welfare assessment at an individual level is
commonplace. Zoo keepers often have many years of experience with particular species
and individual animals and are thus well-placed to assess welfare through sometimes
quite subtle changes in appearance or activity, which can be objectively recorded
and reported over time, using available tools such as WelfareTrack® (23). Superimposed
upon individual-level assessment, there are also increasing numbers of projects within
the zoo community that seek to combine multi-institutional data and information to
identify patterns in welfare issues for particular species, that may be previously
unidentified without such collaboration (24).
Animal Welfare and the “Big Picture”
Animal welfare is an important societal concern and as a scientific field of study,
animal welfare is one of the branches of specialized science that is most accessible
and inherently interesting to the majority of the general public. This is a good thing,
as public importance and relevance opens minds and doors to expansion and application
of our science. As I touched on above, the original concept of QoL from a human point
of view was to encompass aspects of the physical and social environment. For a great
many people, their relationships or interactions with animals constitutes a large
part of their daily life, and the quality of that life, be it with animals owned as
companions or as a source of income, or with free-living animals within their ecosystem.
As the global population continues to grow, there are a number of societal “Big Picture”
challenges that are being, and will continue to need to be addressed, and with which
animal welfare is intrinsically tied. Thus, as animal welfare scientists, it is more
essential than ever that we do not live wholly within the bubble of animal welfare
science and that we expand our horizons outside a relatively narrow scientific discipline
to interact with, inform and learn from others working on global issues, which themselves
are interconnected.
Animal welfare, population growth, global food security, and sustainability
Food security is access by all people at all times to enough food for an active, healthy
life (25) and it means having a reliable source of food and sufficient resources to
purchase it. A family is considered food secure when its members do not live in hunger
or fear of starvation. For those of us working in animal agriculture, we are constantly
reminded of projected global population growth over the next 35 years, with an expected
increase in global population from the current 7.2 billion up to 9.6 billion by 2050.
Concomitant with this increase in overall population is a projected increase in overall
food demand and a projected per capita increase in demand for food from animal sources,
especially in developing countries. At present, more than 1 billion people are food
insecure. As the global population increases, the number of people with an insecure
food supply will also dramatically increase unless there is an increase in food production,
and improvements in food distribution and storage. Given the sizeable stress that
this demand for animal and crop production will place on planetary resources, it is
not surprising that “sustainability” has become a keyword within agriculture as a
whole. The main emphasis is on economic and environmental or ecological sustainability,
but there is also the critical element of ethical or social sustainability (26). The
projected increase in animal production will be achieved by increases in animal numbers
and further increases in productivity – output per unit input. However, although current
projections do show an increase in animal production, it is also probable that the
actual increase will be buffered by a shift in diet away from animal products to foods
from crop sources, either through concerns about animal welfare or sustainability/land-use
efficiency or through perceived health benefits associated with a vegetarian/vegan
diet. Twenty-five years ago, reasons for not eating animal products were mostly due
to animal welfare (66%) and health reasons (26%) rather than environmental/ecological
reasons (1%) (27). Five years ago, a much larger survey found that reasons for dietary
animal-product avoidance were now shifted toward health (40.1%) and environmental/ecological
(38.1%) reasons and away from animal welfare reasons (16.5%) (28). Although these
studies are not directly comparable, they do highlight that consumers are also looking
more at the “big picture” and identifying the relationship between animal production
and sustainability.
Although over the last few decades, livestock farming in developed countries has been
characterized by decreasing farm numbers, increasing farm size, and increased intensification,
its ethical acceptability has been increasingly questioned. There will still be increasing
intensification in newly industrialized and developing countries to meet the growing
food demand, albeit not completely unquestioned. Fully industrialized economies, however,
will continue to see mounting vociferous opposition to farming systems that do not
meet society’s demand for production that is ecologically, environmentally, and ethically
acceptable. Within the ethical acceptability boundary is the notion that animal farming
systems must meet or exceed standards of animal welfare deemed acceptable by the given
society, and this should not be overlooked (29). Even though a system may be environmentally
and economically sustainable, if the animals kept within it are subject to housing
conditions or production demands deemed unacceptable in terms of animal welfare, then
consumer acceptance will evaporate, demand for the product will decrease and the system
of production will ultimately become unsustainable – as seen in confinement housing
systems such as veal crates, battery cages for laying hens, and gestation crates for
sows. Alternatively, public antipathy may reach such a level that rather than a gradual
decline in consumer demand forcing change, legislation may be enacted that outlaws
the production system, either within a localized legislative framework (e.g., single
state or country) or a more broader one (e.g., federal body). Examples of such housing
systems include battery cages for laying hens, crates for veal calves, and crates
for gestating sows.
However, it is not only housing systems being questioned. The public is also concerned
with the animal’s own biological functioning and whether continued “improvements”
in parameters such as litter size, growth rates, egg or milk production can be supported
if the animal’s welfare is negatively impacted in combination. Another animal welfare
concern is the potential impact of increased food production on wildlife, with decreasing
natural habitats as land is converted to crop or animal farming and the culling of
predators or wildlife that may consume crops or compete with farmed animals for resources.
The issue of animal welfare as a component of sustainability and food security is
important as we implement or adapt current systems for use in developing countries,
and design new systems for use in a dynamic, economically interconnected world. Although
the integration of an animal welfare emphasis into livestock and crop production systems
in developing countries can also result in higher biodiversity, restoring habitat,
reversing the impact of traditional production systems (30), and improving QoL, the
standards of acceptable animal welfare are greatly changed by the level of food security
and those of us living in food secure households must be aware that our own baseline
of acceptability may be quite different from those struggling to feed themselves regularly.
Finally, another often overlooked aspect of growth in global population and wealth
is a concomitant increase in the global population of companion animals, particularly
in those countries with developing economies. For example, India has seen a 90% increase
in cat and dog population between 2002 and 2012 (31), and even the U.S. cat and dog
population has increased 15% in that time. In terms of big picture implications, this
rapidly expanding population also puts further pressure on food supply and hence food
security and sustainability. Increasing feral populations of companion animal species
can also impact wildlife and animal and human health.
Animal welfare and climate change
Scientific consensus is that the world’s climate is undergoing change (32). Temperatures
and sea levels are rising and extreme climatic events are increasing in number. Much
of this is attributed to an increase in greenhouse gases as a result of human activities,
including some from animal production (33). Climate change will impact wildlife welfare
in many ways, such as affecting habitat and food sources, decreasing water availability
and shifts in ranges of disease vectors (34) to the extent that many species will
ultimately be at threat of extinction (35). Companion and zoo animals may likewise
be subjected to vector-borne diseases in new geographical areas and challenged by
changes in thermal environment. Climate change will also present potential challenges
in crop and animal production at a time when, as noted above, overall demand will
be increasing. The projected further changes over the twenty-first century are variable,
depending on the projection model used, but the general implications include further
increases, and perhaps fluctuations in temperature and greater variability in precipitation,
resulting in reduced or modified availability of water for agricultural purposes.
So far, there have been very few studies that have tried to quantify the impact of
real-life climate change over the last few decades on livestock production, and those
that have been carried out are focused on modeling projected impacts of future climate
change, or models of disease transmission given the increased range of disease vectors.
However, under experimental conditions, it is well known that heat and cold have very
obvious effects on productivity, and indeed on welfare. Heat stress reduces appetite,
reduces growth, affects reproduction, decreases milk and egg production and, at critical
levels, can lead to heat stroke and death (36). Shifts in both maximum and minimum
temperatures may result in more animals being exposed to both heat and cold stress
events, thereby impacting their welfare.
Changing precipitation patterns may result in current pastoral-based systems having
to adapt either in response to moving away from drought-susceptible areas or having
to surrender high-quality pastureland over to crop production, and moving to reduced
quality areas, with breeds of livestock that are not so well suited for the new, harsher
environment. The changes in climate may also impact disease transmission with disease
vectors, such as insects, becoming established in previously unrecorded areas.
Animal welfare, animal health, and food safety
A recent study estimated that each year in the U.S., about 3% of the population suffers
from an illness due to 1 of 31 known foodborne pathogens. According to these data,
there are approximately 9.4 million illnesses, of which 56,000 require hospitalization,
resulting in 1350 deaths (37). The U.S. Centers for Disease Control and Prevention
estimate much higher figures. They not only include the above data set but also include
data due to “unspecified agents” causing the symptoms of acute gastroenteritis. Combined,
there are 48 million illnesses, 128,000 hospitalizations, and 3000 deaths (38). These
are not all animal-product related, and further estimates within the U.S. put animal-related
foodborne illness as a cause of 42% of illnesses, 46% of hospitalizations, and 43%
of deaths, with major illness-causing agents identified as Listeria, Salmonella, Campylobacter
spp., and Norovirus (39). Expand these estimates to a global population and the impact
of unsafe food, especially in areas with limited access to medical treatment is great.
The World Health Organization estimate 1.9 million children die each year from diarrheal
illnesses and there is a major WHO initiative underway to estimate the “global burden
of foodborne diseases,” which will report in 2015.
How does food safety fit with animal welfare? There is plenty of evidence of a direct
link between animal welfare and animal health. Animals under stress are often immune-compromised
and are more susceptible to disease. Higher levels of disease within an animal population
can result in an increased risk of bacterial or viral contamination within food products
and there is also a risk of medication residues in food products if withdrawal protocols
are not stringently followed. Although the public often consider extensive production
systems as being high welfare and high health, the reality is that decreased biosecurity
in extensive systems may, in fact, increase exposure to, and incidence of certain
diseases (40). There remains a greater need to consider the “farm-to-fork” chain as
a whole and not focus on individual stages of the chain in isolation. Only with a
foundation of high welfare/low stress/high health production systems can we begin
to make real advances in the safety of the final products. Again, this “big picture”
theme is intrinsically linked to the others.
Conclusion
Originally, animal welfare science was heavily behavior-based. As a scientific discipline
in its own right, animal behavior has perhaps been unfairly thought of as a “soft”
science and is still subject to misapplication by non-ethologists assuming they can
study behavior without adequate expertise or training. Done right, behavior is valid
and precise but it has taken the integration of perceived “harder” sciences such as
physiology, immunology, and pathology for animal welfare science to evolve independence
and specialty status. There is also the irony that as we now strive to develop and
incorporate measures that will identify and quantify emotional state, we are perhaps
returning to our ethological roots and becoming more reliant on behavior as a key
component of our science.
As I hope I have illustrated above, there are real opportunities for animal welfare
science to continue to expand our fundamental knowledge of many facets of biological
functioning of the animals with which we interact, and enable us to apply our new-found
knowledge to continue to improve our animals’ lives. A major advantage for our discipline
is its relative accessibility to the general public and to scientists working in other
fields. Animal welfare science is therefore positioned to play a role in some of the
big issues confronting our global society and the opportunities afforded by inter-disciplinary
collaboration should be embraced.
Conflict of Interest Statement
The author declares that the research was conducted in the absence of any commercial
or financial relationships that could be construed as a potential conflict of interest.