Scientific research on ‘animal welfare’ began because of ethical concerns over the quality of life of animals, and the public looks to animal welfare research for guidance regarding these concerns. The conception of animal welfare used by scientists must relate closely to these ethical concerns if the orientation of the research and the interpretation of the findings is to address them successfully.

At least three overlapping ethical concerns are commonly expressed regarding the quality of life of animals: (1) that animals should lead natural lives through the development and use of their natural adaptations and capabilities, (2) that animals should feel well by being free from prolonged and intense fear, pain, and other negative states, and by experiencing normal pleasures, and (3) that animals should function well, in the sense of satisfactory health, growth and normal functioning of physiological and behavioural systems. Various scientists have proposed restricted conceptions of animal welfare that relate to only one or other of these three concerns. Some such conceptions are based on value positions about what is truly important for the quality of life of animals or about the nature of human responsibility for animals in their care. Others are operational claims: (1) that animal welfare research must focus on the functioning of animals because subjective experiences fall outside the realm of scientific enquiry, or (2) that studying the functioning of animals is sufficient because subjective experiences and functioning are closely correlated. We argue that none of these positions provides fully satisfactory guidance for animal welfare research.

We suggest instead that ethical concerns about the quality of life of animals can be better captured by recognizing three classes of problems that may arise when the adaptations possessed by an animal do not fully correspond to the challenges posed by its current environment. (I) If animals possess adaptations that no longer serve a significant function in the new environment, then unpleasant subjective experiences may arise, yet these may not be accompanied by significant disruption to biological functioning. Thus, a bucket-fed calf may experience a strong, frustrated desire to suck, even though it obtains adequate milk. (2) If the environment poses challenges for which the animal has no corresponding adaptation, then functional problems may arise, yet these may not be accompanied by significant effects on subjective feelings. Thus, a pig breathing polluted air may develop lung damage without appearing to notice or mind the problem. (3) Where animals have adaptations corresponding to the kinds of environmental challenges they face, problems may still arise if the adaptations prove inadequate. For example, an animal's thermoregulatory adaptations may be insufficient in a very cold environment such that the animal both feels poorly and functions poorly. We propose that all three types of problems are causes of ethical concern over the quality of life of animals and that they together define the subject matter of animal welfare science.

Contemporary animal welfare thinking is increasingly emphasising the promotion of positive states. There is a need for existing assessment frameworks to accommodate this shift in emphasis. This paper describes extensions to the Five Domains model, originally devised to assess welfare compromise, that facilitate consideration of positive experiences that may enhance welfare. As originally configured, the model provided a systematic method for identifying compromise in four physical/functional domains (nutrition, environment, health, behaviour) and in one mental domain that reflects the animal's overall welfare state understood in terms of its affective experiences. The specific modifications described here now facilitate additional identification in each domain of experiences animals have which may be accompanied by positive affects that would enhance welfare. It is explained why the grading scale and indices for evaluating welfare compromise necessarily differ from those for assessing welfare enhancement. Also, it is shown that the compromise and enhancement grades can be combined to provide a single informative symbol, the scaled use of which covers the range from severe welfare compromise and no enhancement to no compromise and high-level enhancement. Adapted thus, the Five Domains model facilitates systematic and structured assessment of positive as well as negative welfare-related affects, the circumstances that give rise to them and potential interactions between both types of affect, all of which extend the utility of the model. Moreover, clarification of the extended conceptual framework of the model itself contributes to the growing contextual shift in animal welfare science towards the promotion of positive states whilst continuing to minimise negative states.

We estimate that stereotypies are currently displayed by over 85 million farm, laboratory and zoo animals worldwide. This paper investigates their reliability as welfare indicators, by surveying studies relating stereotypy to other welfare measures and by analysing the mechanisms underlying this behaviour. Where data exist, most (approximately 68%) situations that cause/increase stereotypies also decrease welfare. Stereotypy-eliciting situations are thus likely to be poor for welfare, although exceptions exist. Within such an environment, however, most (approximately 60%) accounts link individual stereotypy performance with improved welfare (cf approximately 20% linking it with reduced welfare). Thus, in a sub-optimal environment, non-stereotyping or low-stereotyping individuals could well have the poorest welfare, although again exceptions exist. Examining the mechanisms underlying stereotypy performance, we discuss four processes that could account for these complex links between stereotypy and welfare. Beneficial consequences from performing the specific source-behaviour of the stereotypy (‘do-it-yourself enrichment’), or arising from repetition per se (‘mantra effects’), may ameliorate welfare in poor environments. In addition, stereotypies that have become centrally controlled (habit-like), or that arise from autistic-like changes in the control of all behaviour (perseveration), are likely to be unreliable indicators of current state because they can be elicited by, or persist in, circumstances that improve welfare. To refine the role of stereotypy in welfare assessment, we suggest the collection of specific additional data to reveal when any of these four processes is acting. Until such research increases our understanding, stereotypies should always be taken seriously as a warning sign of potential suffering, but never used as the sole index of welfare; non-stereotyping or low-stereotyping individuals should not be overlooked or assumed to be faring well; simple measures of frequency should not be used to compare stereotypies that differ in age, form, or the biological or experiential characteristics of the performing animal; enrichments that do not immediately reduce stereotypies should not be assumed failures with respect to welfare; and finally, stereotypies should not be reduced by means other than tackling their underlying motivations.

Increasing litter size has long been a goal of pig breeders and producers, and may have implications for pig (Sus scrofa domesticus) welfare. This paper reviews the scientific evidence on biological factors affecting sow and piglet welfare in relation to large litter size. It is concluded that, in a number of ways, large litter size is a risk factor for decreased animal welfare in pig production. Increased litter size is associated with increased piglet mortality, which is likely to be associated with significant negative animal welfare impacts. In surviving piglets, many of the causes of mortality can also occur in non-lethal forms that cause suffering. Intense teat competition may increase the likelihood that some piglets do not gain adequate access to milk, causing starvation in the short term and possibly long-term detriments to health. Also, increased litter size leads to more piglets with low birth weight which is associated with a variety of negative long-term effects. Finally, increased production pressure placed on sows bearing large litters may produce health and welfare concerns for the sow. However, possible biological approaches to mitigating health and welfare issues associated with large litters are being implemented. An important mitigation strategy is genetic selection encompassing traits that promote piglet survival, vitality and growth. Sow nutrition and the minimisation of stress during gestation could also contribute to improving outcomes in terms of piglet welfare. Awareness of the possible negative welfare consequences of large litter size in pigs should lead to further active measures being taken to mitigate the mentioned effects.

This paper reviews the literature on human attitudes to animals, and postulates the existence of two primary motivational determinants of attitudes labelled ‘affect’ and ‘utility’. It also proposes that the relative strengths of these key attitude dimensions are affected by various modifying variables including the specific attributes of the animal, the individual characteristics and experience of the person evaluating the animal, and a range of cultural factors. The role of science as a cultural modifier of human attitudes to animals is also discussed.

Although the physiological and behavioural changes that can indicate poor welfare are generally agreed upon, using these measures in practice sometimes yields results that are hard to interpret. For example, different types of measure may suggest quite different things about an animal's welfare. Such contradictions are often due to the differing properties of the variables being measured. How each variable responds to a stressor can be affected by several factors - the type of unpleasant stimulus to which the animal is exposed; when and for how long exposure occurs; the animal's psychological state, eg does it feel that it is in control?; and the time at which the measurement is made, relative to the stressor. Typical responses also often differ between species and between individuals, and may even change in a single individual over time. Furthermore, some responses used to assess welfare lack specificity: they can be elicited by neutral or even pleasant events as well as by aversive ones. Appreciating these factors is vital when designing experiments, when choosing what to measure along with each welfare variable, and when interpreting results. Even after taking these factors into consideration, interpreting a result can still be difficult. One approach then is to consider the effects on welfare of the changes measured, eg if there is immunosuppression, does the animal succumb to disease? Another is to use the animal's behaviour to indicate its preference for, or aversion to, particular environments. Ultimately, however, interpreting welfare measures involves subjective judgements which will be influenced by the nature of our concern for the animal under consideration. By raising these problems, we hope that this review will highlight and clarify the apparent contradictions that sometimes emerge in scientific studies of animal welfare, and help researchers improve the designs of their experiments for the benefit of the animals concerned.

The Glasgow Composite Measure Pain Scale (CMPS) for dogs suffering acute pain, developed using psychometric methodology, measures pain to a level of precision suitable for clinical trials. However, for routine clinical use, where the emphasis is on speed, ease of use, and guidance for analgesia provision, a short form (CMPS-SF) was developed. The CMPS-SF comprises six behavioural categories with associated descriptive expressions (items): vocalisation (4), attention to wound (5), mobility (5), response to touch (6), demeanour (5) and posture/activity (5). Items are placed in increasing order of pain intensity and numbered accordingly. The observer chooses that item within each category which best describes the dog's behaviour and ranked scores are summed; the maximum pain score is 24, or 20 if mobility is impossible to assess. Veterinary surgeons in Glasgow, University College Dublin and North Carolina Veterinary Schools completed the CMPS-SF for 122 dogs undergoing post-operative care and thereafter were asked “Do you think this animal requires analgesia? Yes/No”. The population difference in median pain score, for dogs considered to require analgesia (seven) compared with those that did not (three), was highly statistically significant (P < 0.001). Consideration of a clinical decision-point for analgesia gave an intervention level of 6/24, and 5/20 when section B (mobility assessment) could not be carried out. Difficulties in recognising pain contribute to the sub-optimal use of analgesics in veterinary practice. The CMPS-SF provides a practical means of assessing acute post-operative pain and provides guidance with regard to analgesic requirement, so improving pain management and welfare. The CMPS-SF can be downloaded from the Glasgow Pain and Welfare website at http://www.gla.ac.uk/vet/painandwelfare.

In hedonic theories of motivation, ‘motivational affective states’ (MASs) are typically seen as adaptations which motivate certain types of behaviour, especially in situations where a flexible or learned response is more adaptive than a rigid or reflexive one. MASs can be negative (eg unpleasant feelings of hunger or pain) or positive (eg pleasant feelings associated with eating and playing). Hedonic theories often portray negative and positive MASs as opposite ends of a one-dimensional scale.

We suggest that natural selection has favoured negative and positive affect as separate processes to solve two different types of motivational problems. We propose that negative MASs (eg thirst, fear) evolved in response to ‘need situations’ where the fitness benefit of an action has increased, often because the action is needed to cope with a threat to survival or reproductive success. We propose that these negative MASs develop in response to a change in the body (eg dehydration) or the environment (eg the approach of a predator) which creates the need for action, and that negative MASs can become intense and prolonged if the threat to fitness is high and persistent. We propose that positive MASs evolved in ‘opportunity situations ‘ where an action (eg playing, exploring) has become advantageous because the fitness cost of performing it has declined. We propose that these positive MASs occur during, or as a result of, the performance of types of behaviour which are beneficial for fitness at a variety of times, not only when they are required to meet immediate needs; and that the pleasure inherent in the behaviour motivates the animal to perform it when the cost of so doing is sufficiently low. Some behaviour (eg eating) can be motivated by both positive and negative affect. Other behaviour, such as playing or fleeing from a predator, may be motivated largely by positive or negative affect alone. Our hypothesis needs to be tested, but we suggest that it corresponds well to common human experience.

The hypothesis provides a basis for predicting whether an aspect of animal management is likely to cause strong and prolonged negative affect (‘suffering’), or to prevent animals from experiencing certain types of pleasure. This distinction is important for bringing animal welfare assessment into line with ethical concerns.

Milk yield per cow has more than doubled in the previous 40 years and many cows now produce more than 20,000 kg of milk per lactation. The increase in production should be viewed with concern because: i) the increase in milk yield has been accompanied by declining fertility, increasing leg and metabolic problems and declining longevity; ii) there are unfavourable genetic correlations between milk yield and fertility, mastitis and other production diseases, indicating that deterioration in fertility and health is largely a consequence of selection for increased milk yield; and iii) high disease incidence, reduced fertility, decreased longevity and modification of normal behaviour are indicative of substantial decline in cow welfare. Improving welfare is important as good welfare is regarded by the public as indicative of sustainable systems and good product quality and may also be economically beneficial. Expansion of the Profitable Lifetime Index used in the UK to include mastitis resistance and fertility could increase economic response to selection by up to 80%, compared with selection for milk production alone. In the last 10 years, several breeding organisations in Europe and North America followed the example of Nordic Countries and have included improving fertility and reducing incidence of mastitis in their breeding objectives, but these efforts are still timid. A multi-trait selection programme in which improving health, fertility and other welfare traits are included in the breeding objective, and appropriately weighted relative to production traits, should be adopted by all breeding organisations motivated in their goal of improving welfare.

A multitude of endocrine mechanisms are involved in coping with challenges. Glucocorticoids, secreted by the adrenal glands, are in the front line of the battle to overcome stressful situations. They are usually measured in plasma samples as parameters of adrenal activity and thus of disturbance. Unfortunately, collecting blood samples itself can disturb an animal. Thus, non-invasive methods for the determination of glucocorticoids or their metabolites have become increasingly popular. The pros and cons of various non-invasive sample materials (saliva, excreta, milk, hair/feathers and eggs) for glucocorticoid determination are given. Above all, faecal samples offer the advantage that they can be collected easily. In faecal samples, circulating hormone levels are integrated over a certain period of time and represent the cumulative secretion of hormones. Thus, the levels are less affected by short fluctuations or the pulse-like nature of hormone secretion. However, using this technique to assess an animal's adrenocortical activity is not especially simple. Whether frequent sampling is necessary or single samples will suffice depends upon the study's aim (whether one is examining the impact of acute or chronic stressors). Background knowledge of the metabolism and excretion of cortisol/corticosterone metabolites is required and a careful validation for each species and sex investigated is obligatory. The present review also addresses analytical issues regarding sample storage, extraction procedures and immunoassays and includes a comprehensive list of published studies (up to 2011) describing the use of such methods in farmed animals. Applied properly, non-invasive techniques to monitor glucocorticoid metabolites in faecal samples of various species are a useful tool for welfare assessment, especially as they are easily applied at farm or group level.

Rather than construct lists of many different welfare indicators and give each of them the same weight, I argue that the assessment of animal welfare should be directed at answering two key questions: I) Are the animals healthy? 2) Do they have what they want? Behaviour has a major role in answering both. Behaviour is currently used to help answer the first question through its use in the clinical and pre-clinical assessment of pain, injury and disease, and potentially could have an even greater role, particularly if used in conjunction with new technology. Behaviour is also of crucial importance in gauging what animals want, most obviously in the use of choice and preference tests, but also through other methods that are particularly suitable for on-farm welfare assessment. These include quantitative observations of the spatial distribution of animals and of behavioural ‘indicators’ of what animals want, such as vocalisations.

Welfare is multidimensional, comprising good health, comfort, expression of behaviour, and so on. Its overall assessment therefore requires a multicriteria evaluation. The set of criteria shall be exhaustive (no missing item), minimal (only necessary items), agreed by stakeholders, and legible (a limited number of criteria). Furthermore, the interpretation from one criterion shall not depend on that from another. We propose a set of 12 subcriteria grouped into four criteria: feeding, housing, health and optimised emotional states. This work will assist in developing measures to be used on-farm to form a European standard for overall assessment of animal welfare.

Historically, pet dogs were trained using mainly negative reinforcement or punishment, but positive reinforcement using rewards has recently become more popular. The methods used may have different impacts on the dogs’ welfare. We distributed a questionnaire to 364 dog owners in order to examine the relative effectiveness of different training methods and their effects upon a pet dog's behaviour. When asked how they trained their dog on seven basic tasks, 66% reported using vocal punishment, 12% used physical punishment, 60% praise (social reward), 51% food rewards and II% play. The owner's ratings for their dog's obedience during eight tasks correlated positively with the number of tasks which they trained using rewards (P< 0.01), but not using punishment (P = 0.5). When asked whether their dog exhibited any of 16 common problematic behaviours, the number of problems reported by the owners correlated with the number of tasks for which their dog was trained using punishment (P< 0.001), but not using rewards (P = 0.17). Exhibition of problematic behaviours may be indicative of compromised welfare, because such behaviours can be caused by— or result in — a state of anxiety and may lead to a dog being relinquished or abandoned. Because punishment was associated with an increased incidence of problematic behaviours, we conclude that it may represent a welfare concern without concurrent benefits in obedience. We suggest that positive training methods may be more useful to the pet-owning community.

Increasing litter size has long been a goal of pig (Sus scrofa domesticus) breeders and producers in many countries. Whilst this has economic and environmental benefits for the pig industry, there are also implications for pig welfare. Certain management interventions are used when litter size routinely exceeds the ability of individual sows to successfully rear all the piglets (ie viable piglets outnumber functional teats). Such interventions include: tooth reduction; split suckling; cross-fostering; use of nurse sow systems and early weaning, including split weaning; and use of artificial rearing systems. These practices raise welfare questions for both the piglets and sow and are described and discussed in this review. In addition, possible management approaches which might mitigate health and welfare issues associated with large litters are identified. These include early intervention to provide increased care for vulnerable neonates and improvements to farrowing accommodation to mitigate negative effects, particularly for nurse sows. An important concept is that management at all stages of the reproductive cycle, not simply in the farrowing accommodation, can impact on piglet outcomes. For example, poor stockhandling at earlier stages of the reproductive cycle can create fearful animals with increased likelihood of showing poor maternal behaviour. Benefits of good sow and litter management, including positive human-animal relationships, are discussed. Such practices apply to all production situations, not just those involving large litters. However, given that interventions for large litters involve increased handling of piglets and increased interaction with sows, there are likely to be even greater benefits for management of hyper-prolific herds.

When individual vertebrates loose grip on their life conditions stress symptoms appear and their welfare becomes problematic. Present day research supports the view that stress can originate when an organism experiences a substantial reduction of predictability and/or controllability (PIC) of relevant events. Behavioural (conflict and disturbed behaviour) and physiological (neuro-endocrine and autonomic processes) aspects of a reduction of PIC are reviewed. The highly dynamic patterns of the homeostatic mechanisms activated during stress make it difficult to deduce any simple relationship between stress and welfare.

A list of relevant stress symptoms has been presented, all of which indicate some stage of serious welfare problems. Their occurrence should never be typical of animals living in a farm, laboratory or zoo housing system. However, if after all this is the case, such systems have to be corrected and replaced by more appropriate ones as soon as possible.

Improving the quality of life of captive animals is dependent on developing valid measures of how animals feel about their lives. It has recently been suggested that biases in information processing may offer a novel means of understanding animal emotions. Anxious and depressed people tend to interpret ambiguous information negatively. We explored the proposal that such cognitive biases also exist in non-human animals and could therefore be used as novel measures of animal welfare. We used a novel cognitive bias task based on a learnt taste aversion to determine whether birds deprived of environmental enrichment show biases in their classification of ambiguous signals. We hypothesised that starlings in enriched cages should be more likely to classify ambiguous signals as being associated with a positive outcome than starlings housed in standard, unenriched cages. Starlings were trained on a go/no-go procedure to discriminate between two visual stimuli (cardboard lids of white and dark grey) associated with outcomes of a different value (palatable and unpalatable mealworms hidden underneath). Individual birds' responses to unreinforced, intermediate stimuli (various shades of grey between white and dark grey) were subsequently examined while each bird was housed sequentially in both standard and enriched cages. The probability of a bird classifying an ambiguous pale grey lid as hiding a palatable mealworm was lower in standard cages than enriched cages, but this difference was found only in birds that received enriched cages first. Our results can be interpreted as showing a pessimistic bias in birds that have recently experienced a decline in environmental quality. These findings support the use of cognitive bias-based tasks as a novel, non-invasive technique for assessing welfare in non-human animals.

In the social debate about animal welfare we can identify three different views about how animals should be raised and how their welfare should be judged: (1) the view that animals should be raised under conditions that promote good biological functioning in the sense of health, growth and reproduction, (2) the view that animals should be raised in ways that minimise suffering and promote contentment, and (3) the view that animals should be allowed to lead relatively natural lives. When attempting to assess animal welfare, different scientists select different criteria, reflecting one or more of these value-dependent views. Even when ostensibly covering all three views, scientists may differ in what they treat as inherently important versus only instrumentally important, and their selection of variables may be further influenced by a desire to use measures that are scientifically respected and can be scored objectively. Value assumptions may also enter animal welfare assessment at the farm and group level (1) when empirical data provide insufficient guidance on important issues, (2) when we need to weigh conflicting interests of different animals, and (3) when we need to weigh conflicting evidence from different variables. Although value assumptions cannot be eliminated from animal welfare assessment, they can be made more explicit as the first step in creating animal welfare assessment tools. Different value assumptions could lead to different welfare assessment tools, each claiming validity within a given set of assumptions.

Selection for brachycephalic (foreshortened muzzle) phenotypes in dogs is a major risk factor for brachycephalic obstructive airway syndrome (BOAS). Clinical signs include respiratory distress, exercise intolerance, upper respiratory noise and collapse. Efforts to combat BOAS may be constrained by a perception that it is ‘normal’ in brachycephalic dogs. This study aimed to quantify owner-perception of the clinical signs of BOAS as a veterinary problem. A questionnaire-based study was carried out over five months on the owners of dogs referred to the Queen Mother Hospital for Animals (QMHA) for all clinical services, except for Emergency and Critical Care. Owners reported the frequency of respiratory difficulty and characteristics of respiratory noise in their dogs in four scenarios, summarised as an ‘owner-reported breathing’ (ORB) score. Owners then reported whether their dog currently has, or has a history of, ‘breathing problems’. Dogs (n = 285) representing 68 breeds were included, 31 of which were classed as ‘affected’ by BOAS either following diagnostics, or by fitting case criteria based on their ORB score, skull morphology and presence of stenotic nares. The median ORB score given by affected dogs’ owners was 20/40 (range 8-30). Over half (58%) of owners of affected dogs reported that their dog did not have a breathing problem. This marked disparity between owners’ reports of frequent, severe clinical signs and their perceived lack of a ‘breathing problem’ in their dogs is of concern. Without appreciation of the welfare implications of BOAS, affected but undiagnosed dogs may be negatively affected indefinitely through lack of treatment. Furthermore, affected dogs may continue to be selected in breeding programmes, perpetuating this disorder.

The notion ‘quality of life’ (QoL) suggests that welfare in animals encompasses more than just an absence of suffering; it concerns the quality of an animal's entire relationship with its environment, of how it lives its life. Judgements of such quality are based on the integration of perceived details of how animals behave over time in different contexts. The scientific status of such judgements has long been ambiguous, but in recent decades has begun to be addressed by animal scientists. This paper starts with a brief review of qualitative approaches to the study of animal behaviour, which tend to address characteristics such as individuality, personality, and emotionality. The question then arises whether such characteristics involve a subjective, experiential aspect, and identify animals as sentient beings. The second half of this paper argues that taking the integrative nature of qualitative judgements seriously enables a ‘whole animal’ perspective, through which it becomes possible to view behaviour as a dynamic, expressive body language that provides a basis for assessing the quality of an animal's experience (eg contented, anxious). Judging this quality is a skill that requires knowledge of species-specific behaviour, experience in observing and interacting with animals in different contexts, and a willingness to communicate with animals as sentient beings. A substantial body of research indicates that this skill can function reliably in a scientific context, and can be applied usefully as a practical welfare assessment tool. Thus qualitative approaches to the study of animal behaviour should make an important contribution to the growing interest in animal QoL.

Pain experienced by lame cattle is often masked by their instinctive stoicism, leading to delayed detection and treatment of lameness. This paper investigates the usefulness of posture scoring during locomotion and the evaluation of daily activity levels as indicators of pain and discomfort resulting from lameness in dairy cattle. In this study, 345 lactating cattle were observed over a seven-month winter housing period. The posture of each cow was scored twice weekly using a subjective five-point numerical rating scale. Daily activity levels were measured objectively using pedometers. The effect of lameness on behaviour was addressed. Increased posture scores were associated with the presence of foot lesions (P < 0.001) and with reduced daily activity levels (P < 0.001). In comparison to sound cows, lame cows showed lower daily activity levels (P < 0.001). These results improve understanding of pain-related behaviours in cattle, and such an approach may assist future development of welfare assessment systems.