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Affective states are reflected in the facial expressions of all mammals. Facial behaviors linked to pain have attracted most of the attention so far in non-human animals, leading to the development of numerous instruments for evaluating pain through facial expressions for various animal species. Nevertheless, manual facial expression analysis is susceptible to subjectivity and bias, is labor-intensive and often necessitates specialized expertise and training. This challenge has spurred a growing body of research into automated pain recognition, which has been explored for multiple species, including cats. In our previous studies, we have presented and studied artificial intelligence (AI) pipelines for automated pain recognition in cats using 48 facial landmarks grounded in cats' facial musculature, as well as an automated detector of these landmarks. However, so far automated recognition of pain in cats used solely static information obtained from hand-picked single images of good quality. This study takes a significant step forward in fully automated pain detection applications by presenting an end-to-end AI pipeline that requires no manual efforts in the selection of suitable images or their landmark annotation. By working with video rather than still images, this new pipeline approach also optimises the temporal dimension of visual information capture in a way that is not practical to preform manually. The presented pipeline reaches over 70% and 66% accuracy respectively in two different cat pain datasets, outperforming previous automated landmark-based approaches using single frames under similar conditions, indicating that dynamics matter in cat pain recognition. We further define metrics for measuring different dimensions of deficiencies in datasets with animal pain faces, and investigate their impact on the performance of the presented pain recognition AI pipeline., (© 2024. The Author(s).)

Detection dogs are required to search for and alert to specific odours of interest, such as drugs, cadavers, disease markers and explosives. However, the odour released from different samples of the same target substance will vary for a number of reasons, including the production method, evaporation, degradation, or by being mixed with extraneous odours. Generalisation, the tendency to respond in the same manner to stimuli which are different - but similar to - a conditioned stimulus, is therefore a crucial requirement for working detection dogs. Odour is a complex modality which poses unique challenges in terms of reliably predicting generalisation, when compared with auditory or visual stimuli. The primary aim of this review is to explore recent advances in our understanding of generalisation and the factors that influence it, and to consider these in light of detection dog training methods currently used in the field. We identify potential risks associated with certain training practices, and highlight areas where research is lacking and which warrant further investigation., (© 2024. The Author(s).)

Domestic cats use visual cues to communicate with conspecifics and humans. This includes the position and movement of the tail. The tail up signal (i.e. tail held vertically with the tip curled) has been identified as a friendly greeting signal between cats and from cats to humans. We present here a report of two cats unable to display the classic tail up signal due to Spitz-like (curled) tail characteristics, a morphology not previously reported in the scientific literature. The cats, a British Shorthair (Mn, 2 y) and Domestic Longhair (Fn, 8.5 y), belonged to different households and were participants in a study of intraspecific social interactions. Video recordings show the cats displaying normal tail movements (waving, swishing, twitching) and position when the tail was hanging down. However, once the tail was raised to a vertical position, it immediately curled over the back. This Spitz-like tail posture was displayed both when greeting people and other cats. It had reportedly been present since adoption. There was no underlying medical history of injury or pain to indicate this was an acquired state. We suggest this Spitz-like tail is a spontaneously occurring anomaly, that does not seem to noticeably impair the cats' communicative abilities, as normal affiliative behaviours were observed during interactions with the cohoused cat. We discuss the significance of this finding in relation to the formation of social bonds and the signalling of affiliative intent., Competing Interests: Declaration of Competing Interest None of the authors have any financial or personal relationships that could inappropriately influence or bias the content of the paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Fear and frustration are two emotions thought to frequently contribute to problem behaviour, often leading to relinquishment. Inferring these emotions is challenging as they may present with some similar general signs, but they potentially require different treatment approaches to efficiently address the behaviour of concern. Although behavioural assessment frameworks have been proposed, it is largely unknown how clinical animal behaviourists (CABs) assimilate information about the emotional state of an animal to inform their behavioural assessment. In other fields (such as both in human and veterinary medicine), the use of intuition and gut feelings, without the concurrent use of an assessment framework, can lead to higher rates of error and misdiagnosis. Therefore, this study used semi-structured interviews of ten CABs and qualitative methods to explore the ways they conceptualise, recognise and differentiate fear and frustration in dogs. Although interviewees perceived fear and frustration as negative affective states that lead to changes in an animal's behaviour, there was little consensus on the definition or identification or differentiation of these emotions. The use of a scientific approach (i.e., hypothesis-driven and based on falsification of competing hypotheses) for behavioural assessment was highly variable, with individual assessment processes often characterised by tautology, intuition, circular reasoning and confirmation bias. Assessment was typically based on professional judgment, amalgamating information on interpretation of communicative signals, motivation, learning history, breed, genetics and temperament. Given the lack of consensus in the definition of these states, it is clearly important that authors and clinicians define their interpretation of key concepts, such as fear and frustration, when trying to communicate with others., Competing Interests: The authors declare no conflicts of interest. This study contributes towards the PhD of one of the authors (Wilson, B. M).

Animal affective computing is an emerging new field, which has so far mainly focused on pain, while other emotional states remain uncharted territories, especially in horses. This study is the first to develop AI models to automatically recognize horse emotional states from facial expressions using data collected in a controlled experiment. We explore two types of pipelines: a deep learning one which takes as input video footage, and a machine learning one which takes as input EquiFACS annotations. The former outperforms the latter, with 76% accuracy in separating between four emotional states: baseline, positive anticipation, disappointment and frustration. Anticipation and frustration were difficult to separate, with only 61% accuracy., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Feighelstein et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

As brachycephalic dog breed ownership increases, there is a growing concern for the welfare of these breeds due to extreme brachycephalism. Understanding the motivations and behaviours of those choosing to own these breeds is important if we wish to address these concerns. The aim of this study was to investigate how owners of brachycephalic and non-brachycephalic dog breeds use social media dog breed groups to discuss common health issues. The purpose of Facebook posts in relation to common health issues, owner awareness of health issues and the role of Facebook facilitated social support were explored between brachycephalic and non-brachycephalic dog owners. Twelve Facebook breed goups were selected (brachycephalic breed groups, n = 6, non-brachycephalic breed groups, n = 6). Using key word searches we extracted the first twenty posts from each group. Thematic analysis revealed three overarching themes: advice seeking, advice giving and community bonding mechanisms. Whilst the purpose of posting did not differ between groups, non-brachycephalic owners appeared to display greater awareness of breed-specific health issues, whilst social support played a more prominent role in brachycephalic groups. This research highlights that social media groups can act as platforms for knowledge exchange and emotional support. These could be utilised by owners, veterinarians and welfare organisations to more effectively enhance dog health and wellbeing.

Sudden changes in sound and light (e.g., sirens and flashing police beacons) are a common component of working dogs' on-duty environment. Yet, how such stimuli impact dogs' ability to perform physical and cognitive tasks has not been explored. To address this shortcoming, we compared the accuracy and time taken for twelve dogs to complete a complex physical and cognitive task, before, during and after exposure to three 'real-world' stimuli: an acoustic distractor (85dB), white strobe lighting (5, 10 & 15 Hz), and exposure to a dazzling white, red, or blue lights. We found that strobe lighting, and to a greater extent, acoustic distraction, significantly reduced dogs' physical performance. Acoustic distraction also tended to impair dogs' cognitive performance. Dazzling lights had no effect on task performance. Most (nine out of twelve) dogs sensitised to the acoustic distraction to the extent of non-participation in the rewarded task. Our results suggest that without effective distractor response training, sudden changes in noise and flickering lights are likely to impede cognitive and physical task performance in working dogs. Repeated uncontrolled exposure may also amplify these effects., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Sheldon et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Pain is a subjective, aversive sensory and emotional experience and can cause or exacerbate problem behaviors. In this review, the biobehavioral model of pain is introduced and used to improve understanding by veterinarians of pain mechanisms and their relationship with problem behaviors. A range of potential indicators of discomfort are presented, illustrated by selected cases from the authors' behavior and pain referral clinics. Various myths exist around pain resulting in barriers to reporting assessment and treatment. Veterinarians should always consider discomfort in any case presenting with a problem behavior., Competing Interests: Disclosure D.S. Mills and F.M. Coutts have both received funding from Boehringer Ingelheim for veterinary education activities related to pain in dogs., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Despite numerous qualitative and cross-sectional studies investigating how dog-related factors may impact owners' well-being, empirical studies to test these causal effects are lacking. This prospective cohort study examined the correlation and potential causal effect of 17 dog-related factors with six well-being outcomes (depression, anxiety, loneliness, suicidal ideation, hedonic well-being and eudaimonic well-being) in dog owners. Over a four-week period, 709 adult dog owners reported their weekly well-being and occurrence of each dog-related factor (e.g. how many times they ran with their dogs). A random intercept cross-lagged panel model (RI-CLPM) with significance threshold set at 0.001 was used. Six factors correlated with poorer owner well-being (i.e. aggressive dog behaviour, fearful dog behaviour, poor dog health, failure to provide for the dog, lack of control over the dog, and dog presence). Only 'friendly conversation with others due to the dog' correlated with better well-being. Purposeful reductions in the frequency of dog behavioural and health-related issues are likely to improve owner well-being, as well as greater consistency in dog care (i.e. provide for the dog) and more engagement in friendly dog-facilitated social interactions. No potential causal effects were significant. Further studies investigating causal relationships are essential to improve people's well-being through dog ownership., (© 2023. The Author(s).)

The ability to infer emotional states and their wider consequences requires the establishment of relationships between the emotional display and subsequent actions. These abilities, together with the use of emotional information from others in social decision making, are cognitively demanding and require inferential skills that extend beyond the immediate perception of the current behaviour of another individual. They may include predictions of the significance of the emotional states being expressed. These abilities were previously believed to be exclusive to primates. In this study, we presented adult domestic dogs with a social interaction between two unfamiliar people, which could be positive, negative or neutral. After passively witnessing the actors engaging silently with each other and with the environment, dogs were given the opportunity to approach a food resource that varied in accessibility. We found that the available emotional information was more relevant than the motivation of the actors (i.e. giving something or receiving something) in predicting the dogs' responses. Thus, dogs were able to access implicit information from the actors' emotional states and appropriately use the affective information to make context-dependent decisions. The findings demonstrate that a non-human animal can actively acquire information from emotional expressions, infer some form of emotional state and use this functionally to make decisions., (© 2021. The Author(s).)

Background: Assessment of pain in macaques is challenging. The aims of this study were (1) to investigate current knowledge and attitudes of primate veterinarians concerning acute pain in macaques; (2) to synthesise current knowledge and opinion to facilitate pain assessment. A primary question of interest was whether more confident individuals differ in their knowledge and attitudes from less-confident individuals., Methods: An online survey was conducted amongst primate veterinarians serving both laboratories and zoos/sanctuaries. The questionnaire consisted of demographic information, attitudes towards pain, pain rating and analgesics, pain recognition and confidence in recognising pain and sources of information used., Results and Conclusions: There was generally good use of analgesia by respondents. More confident individuals reported that they recognise pain both behaviourally and in facial expressions, rated all pain signs more highly and used more analgesics. Specialist support networks aimed at increasing veterinarian confidence in macaque pain assessment could be beneficial., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Human-directed aggression by domestic dogs is a major worldwide public health problem. The causes of aggression are complex, and research in this area often has to balance ecological validity with pragmatic controls; accordingly, it often does not meet the thresholds for quality typically used in reviews applying a classical "evidence-based" approach. Here, we propose a method of literature assessment that makes the "best use" of available evidence to identify and synthesise evidence relating to the most likely risk factors reported in the scientific literature. We used a systematic review process to initially identify relevant literature relating to potential early life experience (i.e., in the first six months of life) risk factors in the dog for human-directed aggression in the adult animal. Fourteen papers met our initial screening process and were subsequently analysed in detail, with data extracted and effect sizes calculated where possible. This highlighted the potential importance of the source of the animal, the age at which it was rehomed, the reason for the acquisition, the experience level of the owner, the animal's socialisation experiences, the consistent husbandry and management practices, the training, the sex ratio of the litter and the history of dogs that display aggression in the pedigree as risk factors. Taken together, it seems that early experiences which limit the ability to develop effective coping strategies and routines may be particularly important. We provide guidance for the future standardised reporting of risk related to human-directed aggression by dogs to allow greater synthesis of the literature in the future.

Manual tools for pain assessment from facial expressions have been suggested and validated for several animal species. However, facial expression analysis performed by humans is prone to subjectivity and bias, and in many cases also requires special expertise and training. This has led to an increasing body of work on automated pain recognition, which has been addressed for several species, including cats. Even for experts, cats are a notoriously challenging species for pain assessment. A previous study compared two approaches to automated 'pain'/'no pain' classification from cat facial images: a deep learning approach, and an approach based on manually annotated geometric landmarks, reaching comparable accuracy results. However, the study included a very homogeneous dataset of cats and thus further research to study generalizability of pain recognition to more realistic settings is required. This study addresses the question of whether AI models can classify 'pain'/'no pain' in cats in a more realistic (multi-breed, multi-sex) setting using a more heterogeneous and thus potentially 'noisy' dataset of 84 client-owned cats. Cats were a convenience sample presented to the Department of Small Animal Medicine and Surgery of the University of Veterinary Medicine Hannover and included individuals of different breeds, ages, sex, and with varying medical conditions/medical histories. Cats were scored by veterinary experts using the Glasgow composite measure pain scale in combination with the well-documented and comprehensive clinical history of those patients; the scoring was then used for training AI models using two different approaches. We show that in this context the landmark-based approach performs better, reaching accuracy above 77% in pain detection as opposed to only above 65% reached by the deep learning approach. Furthermore, we investigated the explainability of such machine recognition in terms of identifying facial features that are important for the machine, revealing that the region of nose and mouth seems more important for machine pain classification, while the region of ears is less important, with these findings being consistent across the models and techniques studied here., (© 2023. The Author(s).)

Comparative studies of human-dog cognition have grown exponentially since the 2000's, but the focus on how dogs look at us (as well as other dogs) as social partners is a more recent phenomenon despite its importance to human-dog interactions. Here, we briefly summarise the current state of research in visual perception of emotion cues in dogs and why this area is important; we then critically review its most commonly used methods, by discussing conceptual and methodological challenges and associated limitations in depth; finally, we suggest some possible solutions and recommend best practice for future research. Typically, most studies in this field have concentrated on facial emotional cues, with full body information rarely considered. There are many challenges in the way studies are conceptually designed (e.g., use of non-naturalistic stimuli) and the way researchers incorporate biases (e.g., anthropomorphism) into experimental designs, which may lead to problematic conclusions. However, technological and scientific advances offer the opportunity to gather much more valid, objective, and systematic data in this rapidly expanding field of study. Solving conceptual and methodological challenges in the field of emotion perception research in dogs will not only be beneficial in improving research in dog-human interactions, but also within the comparative psychology area, in which dogs are an important model species to study evolutionary processes., (© 2023. The Author(s).)

Background: Connections between the effects of pet ownership and exercise on mental health have previously been demonstrated in different populations. However, little is known about the potential effects of pet ownership and exercise on the mental health of veterinary professionals. Since these individuals have a high prevalence of poor mental health and suicide, while they deal with pets professionally, we investigated the impact of pet ownership, exercise and different types of pet ownership on this demographic group., Method: Veterinary professionals over 18 years old answered an online questionnaire about pet ownership, exercise, mental health (including anxiety, depression and suicidal ideation) and mental health correlates. Regression models were used to identify variables significantly related to mental health outcomes., Results: Of 1087 respondents, pet owners were more depressed than non-owners, while anxiety or suicidal ideation was not associated with pet ownership. Dog and horse owners were psychologically healthier (less anxiety, less suicidal ideation) than non-owners of these species. Veterinary professionals who ran regularly had lower anxiety and depression. Those who walked regularly and spent less time sitting experienced fewer depression symptoms., Conclusions: Running, walking and avoiding prolonged sitting might protect the mental health of veterinary professionals. The type of pet owned may be an important factor in the relationship between pet ownership and mental health; however, generally, pet ownership was associated with worse mental health outcomes in this demographic group. Future studies should determine the causal nature of these relationships., Competing Interests: The authors declare they have no conflicts of interest., (© 2023 The Authors. Veterinary Record Open published by John Wiley & Sons Ltd on behalf of British Veterinary Association.)

Dogs are good models for studying behaviour and cognition as they have complex social capabilities. In the current study, we observed how human emotional valences (positive, neutral and negative) affected aspects of dogs' behaviour. We expected that dogs would exhibit more approaching behaviours in the positive condition and more signs of avoidance in the negative one. We analysed videos of 70 adult pet dogs of various breeds taken from an experiment in which one of two actors expressed an emotion and dogs could freely explore the environment for 30 s. Our results show that dogs exhibit differential behaviour when presented with different emotional valences. Two behaviours arose that might be linked to a reciprocal positive emotional state in dogs: tail raised between 90° and 180° and physical contact during sniffing. These behaviours are associated with an active search for information. In the positive conditions, dogs were more willing to explore the social environment and gather information from the actors.

During the COVID-19 pandemic, lockdowns provided an opportunity to assess what factors, including changes in an owner's routine and time spent at home, were associated with changes in dog behaviour. We undertook a longitudinal survey over a period of 8 months during which we asked about people's work patterns, dog management, and their dogs' behaviour. Generalized linear models revealed that the pre-existence of signs of potential separation-related problems, and especially vocalisation, self-injury, and chewing to escape confinement, was associated with an increase in a range of separation issues. Dogs showing separation-related signs prior to COVID were also more likely to develop more problems during lockdown. Management changes tended to result in increased physical and social stress, with a range of potential compensatory actions taken by the dog, however these signs of stress did not generally appear to be connected to separation-related issues. Survival analysis was used to investigate the emergence of specific issues over time. This indicated that a change to working from home was related initially to a decreased risk of aggression towards the owner, but over time, those who continued to work from the home were at an increased risk of this problem. No other significant time-related relationships were found.

Pain associated with chronic health conditions in non-human animals is an important animal welfare issue. To identify animals in pain and develop an understanding of the mechanisms by which pain affects behaviour, it is therefore important to establish the direct behavioural effects of painful health conditions. We reanalyse data from a cross-sectional survey that considered the presence or absence of a painful condition in dogs and quantified their affective predispositions using the Positive and Negative Activation Scale (PANAS). By applying ideas from network theory, we conceptualise pain as a stressor that exerts direct effects on a network of interacting behavioural variables, and subsequently estimated a network model of conditional dependence relations. Painful health conditions were positively conditionally associated with age (posterior mean partial correlation, ρ = 0.34; standard deviation [SD]=0.05), and negatively conditionally associated with the item 'your dog is full of energy' (ρ = -0.14; SD=0.06). In turn, the energy item was conditionally associated with other PANAS items which were marginally associated with pain, such as items representing ease of excitability and persistence in play. This suggests these marginal effects might be indirectly mediated via the energy item. Further, utilising the posterior predictive distribution we estimated that the median conditional probability (95% credible interval) of a painful health condition given an answer of 'strongly agree' on the energy item was 0.08 (0.05, 0.11), which increased to 0.32 (0.09, 0.58), given a response of 'strongly disagree'. This provides a potentially clinically useful interpretation of the conditional dependencies detected in the network., Competing Interests: Conflict of interest statement None of the authors has any financial or personal relationships that could inappropriately influence or bias the content of the paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Facial expressions are a core component of the emotional response of social mammals. In contrast to Darwin's original proposition, expressive facial cues of emotion appear to have evolved to be species-specific. Faces trigger an automatic perceptual process, and so, inter-specific emotion perception is potentially a challenge; since observers should not try to "read" heterospecific facial expressions in the same way that they do conspecific ones. Using dynamic spontaneous facial expression stimuli, we report the first inter-species eye-tracking study on fully unrestrained participants and without pre-experiment training to maintain attention to stimuli, to compare how two different species living in the same ecological niche, humans and dogs, perceive each other's facial expressions of emotion. Humans and dogs showed different gaze distributions when viewing the same facial expressions of either humans or dogs. Humans modulated their gaze depending on the area of interest (AOI) being examined, emotion, and species observed, but dogs modulated their gaze depending on AOI only. We also analysed if the gaze distribution was random across AOIs in both species: in humans, eye movements were not correlated with the diagnostic facial movements occurring in the emotional expression, and in dogs, there was only a partial relationship. This suggests that the scanning of facial expressions is a relatively automatic process. Thus, to read other species' facial emotions successfully, individuals must overcome these automatic perceptual processes and employ learning strategies to appreciate the inter-species emotional repertoire.

The concept of psychological resilience is well-explored in the human literature and is often described as the ability to 'bounce back' following adversity. However, it remains a neglected research area in dogs despite observations that like humans, dogs vary in their ability to cope with stress. This study aimed to develop the first canine 'resilience' scale. An on-line survey was developed for owners. This covered demographics, medical/behavioural history of the dog, and 19 potential resilience items assessed using a 5-point Likert scale; 1084 complete responses were received during the survey period, with 329 respondents subsequently completing the questionnaire a second time, 6-8 weeks later. Intra-rater reliability was assessed, and only reliable items retained. A principal component analysis (PCA) with varimax rotation was then performed with components extracted on the basis of the inspection of scree plots and the Kaiser criterion. Items were retained if they loaded >0.4 onto one of the components but removed if they cross-loaded onto more than one component. This resulted in a 14-item, 2-component solution. One component appeared to describe "Adaptability/behavioural flexibility" and the other "Perseverance", which are described in the human literature on resilience. Predictive validity was established for expected correlates, such as problem behaviour. The resulting instrument was called the Lincoln Canine Adaptability and Resilience Scale (L-CARS) and is the first to be developed for the assessment of resilience in dogs.

The correct interpretation of an animal's emotional state is crucial for successful human-animal interaction. When studying dog and cat emotional expressions, a key source of information is the pet owner, given the extensive interactions they have had with their pets. In this online survey we asked 438 owners whether their dogs and/or cats could express 22 different primary and secondary emotions, and to indicate the behavioral cues they relied upon to identify those expressed emotions. Overall, more emotions were reported in dogs compared to cats, both from owners that owned just one species and those that owned both. Although owners reported a comparable set of sources of behavioral cues (e.g., body posture, facial expression, and head posture) for dogs and cats in expressing the same emotion, distinct combinations tended to be associated with specific emotions in both cats and dogs. Furthermore, the number of emotions reported by dog owners was positively correlated with their personal experience with dogs but negatively correlated with their professional experience. The number of emotions reported in cats was higher in cat-only households compared to those that also owned dogs. These results provide a fertile ground for further empirical investigation of the emotional expressions of dogs and cats, aimed at validating specific emotions in these species.

Intraspecific social interactions in domestic cats are often categorised as affiliative or agonistic. However, public or professional assessment of encounters can have difficulty distinguishing rough-and-tumble play from true agonism. One possible issue is the potential occurrence of elements of both, play and agonism, within inter-cat play, for example when one cat wants to terminate a bout of play but the other seeks to continue the interaction, which subsequently may provoke more overt agonistic behaviour. To test this hypothesis, we conducted behavioural observations of 105 unique dyadic interactions of domestic cats (N = 210) captured on videos collected from owners and YouTube. We assessed cats for the frequency and duration of six behavioural elements. The dataset was reduced using PCA with a varimax rotation and factor scores were used to classify the population using hierarchical cluster analysis. To validate the identified clusters, the average scores of the constituent factors were compared and the data on interactions were labelled by four cat behaviour experts as "playful", "intermediate" or "agonistic". In addition, to evaluate properties of expert-labelled categories we used linear discriminant analysis followed by an ordinal regression. The results showed considerable convergent validity in factor distributions between clusters and expert-labelled groups: reciprocal wrestling was most closely associated with a group of playfully interacting cats, while vocalisation and chasing were associated with the agonistic group. The intermediate group, while having characteristics of both, was more closely related to the playful group than the agonistic group, with prolonged exchanges of interactive behaviours being a predominant feature. Thus, our findings support the suggestion of there being an intermediate category between mutual social play and agonism. This might escalate into a fully agonistic encounter, but does not necessarily reflect a break down in their social relationship but rather a short-term disagreement in social priorities., (© 2023. The Author(s).)

In animal research, automation of affective states recognition has so far mainly addressed pain in a few species. Emotional states remain uncharted territories, especially in dogs, due to the complexity of their facial morphology and expressions. This study contributes to fill this gap in two aspects. First, it is the first to address dog emotional states using a dataset obtained in a controlled experimental setting, including videos from (n = 29) Labrador Retrievers assumed to be in two experimentally induced emotional states: negative (frustration) and positive (anticipation). The dogs' facial expressions were measured using the Dogs Facial Action Coding System (DogFACS). Two different approaches are compared in relation to our aim: (1) a DogFACS-based approach with a two-step pipeline consisting of (i) a DogFACS variable detector and (ii) a positive/negative state Decision Tree classifier; (2) An approach using deep learning techniques with no intermediate representation. The approaches reach accuracy of above 71% and 89%, respectively, with the deep learning approach performing better. Secondly, this study is also the first to study explainability of AI models in the context of emotion in animals. The DogFACS-based approach provides decision trees, that is a mathematical representation which reflects previous findings by human experts in relation to certain facial expressions (DogFACS variables) being correlates of specific emotional states. The deep learning approach offers a different, visual form of explainability in the form of heatmaps reflecting regions of focus of the network's attention, which in some cases show focus clearly related to the nature of particular DogFACS variables. These heatmaps may hold the key to novel insights on the sensitivity of the network to nuanced pixel patterns reflecting information invisible to the human eye., (© 2022. The Author(s).)

Domestic dogs (Canis familiaris) hold a unique position in human society, particularly in their role as social companions; as such, it is important to understand their emotional lives. There has been growing interest in studying behavioural biases in dogs as indirect markers (reflecting lateralized brain activity) of their emotional states. In this paper, we not only review the previous literature on emotion-related behavioural lateralization in dogs, but also propose and apply the concept of evidential weight to previous research. This allows us to examine different hypotheses about emotion-related brain asymmetries (i.e., Right-Hemisphere-, Valence-, Approach-Withdrawal-Hypothesis) on the basis of a "likelihood-ist" concept of evidence. We argue that previous studies have not been able to discriminate well between competing hypotheses and tended to focus on confirmation bias than critically assess different hypotheses; as such there is a strong case for more systematic investigation to pull these theories apart. We present the areas for future research and explain their importance for understanding the emotional lives of dogs., Competing Interests: Declarations of interest None., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Changes in facial expression provide cues for assessing emotional states in mammals and may provide non-verbal signals of pain. This study uses geometric morphometrics (GMM) to explore the facial shape variation in female Japanese macaques who underwent experimental laparotomy. Face image samples were collected from video footage of fourteen macaques before surgery and 1, 3, and 7 days after the procedure. Image samples in the pre-surgical condition were considered pain-free, and facial expressions emerging after surgery were investigated as potential indicators of pain. Landmarks for shape analysis were selected based on the underlying facial musculature and their corresponding facial action units and then annotated in 324 pre-surgical and 750 post-surgical images. The expression of pain is likely to vary between individuals. Tightly closed eyelids or squeezed eyes and lip tension were the most commonly observed facial changes on day 1 after surgery (p < 0.01974). A good overall inter-rater reliability [ICC = 0.99 (95% CI 0.75-1.0)] was observed with the method. The study emphasizes the importance of individualized assessment and provides a better understanding of facial cues to pain for captive macaque care., (© 2022. The Author(s).)

Both the public and clinicians are interested in the application of scientific knowledge concerning problem animal behaviour and its treatment. However, in order to do this effectively it is essential that individuals have not only scientific literacy but also an appreciation of philosophical concepts underpinning a particular approach and their practical implications on the knowledge generated as a result. This paper highlights several common misunderstandings and biases associated with different scientific perspectives relevant to clinical animal behaviour and their consequences for how we determine what may be a useful treatment for a given patient. In addition to more reflective evaluation of results, there is a need for researchers to report more information of value to clinicians; such as relevant treatment outcomes, effect sizes, population characteristics. Clinicians must also appreciate the limitations of population level study results to a given case. These challenges can however be overcome with the careful critical reflection using the scientific principles and caveats described.

Aggressive behaviour by dogs is a considerable social problem, but the ability to predict which individuals may have increased aggressive tendencies is very limited, restricting the development of efficient preventive measures. There is a common perception that certain breeds are more likely to exhibit aggressive behaviour, which has contributed to the introduction of breed-specific legislation. The rationale for such legislation explicitly assumes high heritability of this trait while also implying relatively little variation within breeds; these assumptions are largely untested. We compared behavioural tendencies between 8 breeds that are subject to legislation in at least one country and 17 breeds that are not subject to legislation using two validated psychometric tools: the Dog Impulsivity Assessment Scale (DIAS), which scores elements of impulsivity, including a tendency for aggressive behaviour, and Positive and Negative Activation Scale (PANAS), which scores sensitivity to positive and negative stimuli (which may trigger aggressive responses). We found that the two groups of breeds do not differ significantly in the specific DIAS factor relating to aggressive behaviour, "Aggression Threshold and Response to Novelty", or any other DIAS and PANAS factors. We found large variations in all behavioural tendencies measured by both psychometric scales within both groups and within each breed studied. Taken together, our findings indicate that breed alone is not a reliable predictor of individual behavioural tendencies, including those related to aggression, and therefore breed-specific legislation is unlikely to be an effective instrument for reducing risk., Competing Interests: The authors declare no conflicts of interest., (© 2022 The Authors. Evolutionary Applications published by John Wiley & Sons Ltd.)

Facial expressions in non-human animals are closely linked to their internal affective states, with the majority of empirical work focusing on facial shape changes associated with pain. However, existing tools for facial expression analysis are prone to human subjectivity and bias, and in many cases also require special expertise and training. This paper presents the first comparative study of two different paths towards automatizing pain recognition in facial images of domestic short haired cats (n = 29), captured during ovariohysterectomy at different time points corresponding to varying intensities of pain. One approach is based on convolutional neural networks (ResNet50), while the other-on machine learning models based on geometric landmarks analysis inspired by species specific Facial Action Coding Systems (i.e. catFACS). Both types of approaches reach comparable accuracy of above 72%, indicating their potential usefulness as a basis for automating cat pain detection from images., (© 2022. The Author(s).)

Research with humans and other animals has suggested that preferential limb use is linked to emotionality. A better understanding of this still under-explored area has the potential to establish limb preference as a marker of emotional vulnerability and risk for affective disorders. This study explored the potential relationship between paw preference and emotionality in pet dogs. We examined which paw the dogs preferentially used to hold a Kong™ and to perform two different locomotion tests. Dogs' emotionality was assessed using a validated psychometric test (the Positive and Negative Activation Scale-PANAS). Significant positive correlations were found for dogs' paw use between the different locomotion tasks, suggesting that dogs may show a more general paw preference that is stable across different types of locomotion. In comparison, the correlations between the Kong™ Test and locomotion tests were only partially significant, likely due to potential limitations of the Kong™ Test and/or test-specific biomechanical requirements. No significant correlations were identified between paw preference tests and PANAS scores. These results are in contrast to previous reports of an association between dog paw preference and emotionality; animal limb preference might be task-specific and have variable task-consistency, which raises methodological questions about the use of paw preference as a marker for emotional functioning.

Arousal and distress are often important factors in problematic behaviours, and endogenous corticosteroids are important mediators in the associated stress responses. Exogenous corticosteroid treatments have been reported to change behaviour in human patients and laboratory animals, with similar changes also noted in pet dogs. These behaviours not only potentially adversely impact the welfare of the dogs, but also the quality of life of their owners. Indeed, corticosteroids can bias sensitivity towards aversion in dogs. A decrease in behaviours associated with positive affective states, such as play and exploratory behaviours, together with an increase in aggression and barking have also been described in dogs. According to the available literature, human patients with pre-existing psychiatric disorders are more at risk of developing behavioural side effects due to corticosteroid treatments. It is reasonable to consider that the same may happen in dogs with pre-existing behavioural problems. In this paper, the possible behavioural side effects of exogenous corticosteroids are summarised to help inform and support veterinarians prescribing these drugs.

Behavioural reactions towards a dead conspecific have been observed rarely in wild canids and there is no documented scientific evidence of grief in pet dogs. A quantitative analysis of grief-related responses in both dogs and owners was conducted, using the validated online Mourning Dog Questionnaire. The survey was completed by 426 Italian adults who had owned at least two dogs, one of whom died while the other was still alive. This research aims to explore whether, how and what a dog may experience over the loss of a companion dog. Multiple logistic regression indicates that both a friendly or parental relationship between two dogs but also the fact that dogs used to share food and the owner's grief and anger are principal predictors of negative behavioural changes. According to dog owners' answers, the surviving dog after the death of the companion dog changed both in terms of activities ("playing", "sleeping", and "eating") and emotions (fearfulness), which occurred as a function of the quality of the relationship between the two animals. By contrast, the time the two dogs had spent together had no effect on the behaviours of surviving dog. Owner perceptions about their dog's reactions and emotions were not related to the memory or suffering of the event that tended to diminish over time. These findings indicate that a dog may show grief-related behavioural and emotional patterns when a close conspecific dies, with aspects of the latter possibly related to the owner's emotional status., (© 2022. The Author(s).)

Facial expressions potentially serve as indicators of animal emotions if they are consistently present across situations that (likely) elicit the same emotional state. In a previous study, we used the Dog Facial Action Coding System (DogFACS) to identify facial expressions in dogs associated with conditions presumably eliciting positive anticipation (expectation of a food reward) and frustration (prevention of access to the food). Our first aim here was to identify facial expressions of positive anticipation and frustration in dogs that are context-independent (and thus have potential as emotion indicators) and to distinguish them from expressions that are reward-specific (and thus might relate to a motivational state associated with the expected reward). Therefore, we tested a new sample of 28 dogs with a similar set-up designed to induce positive anticipation (positive condition) and frustration (negative condition) in two reward contexts: food and toys. The previous results were replicated: Ears adductor was associated with the positive condition and Ears flattener, Blink, Lips part, Jaw drop, and Nose lick with the negative condition. Four additional facial actions were also more common in the negative condition. All actions except the Upper lip raiser were independent of reward type. Our second aim was to assess basic measures of diagnostic accuracy for the potential emotion indicators. Ears flattener and Ears downward had relatively high sensitivity but low specificity, whereas the opposite was the case for the other negative correlates. Ears adductor had excellent specificity but low sensitivity. If the identified facial expressions were to be used individually as diagnostic indicators, none would allow consistent correct classifications of the associated emotion. Diagnostic accuracy measures are an essential feature for validity assessments of potential indicators of animal emotion., (© 2021. The Author(s).)

Rehoming organisations often undertake some type of behaviour evaluation to determine dogs' suitability for rehoming and/or the type of suitable home. Assessments can carry considerable weight in determining dogs' fates. Although evaluation of the validity and reliability of any test is important, a more fundamental consideration is if the nature of the information sought and the weight given to this in organisations' decision making is of more than anecdotal value. Therefore, this study's aim was to conduct a qualitative analysis of organisations' pre-adoption dog behaviour screenings and potential justifications, comparing this with the available scientific evidence. A written enquiry was sent electronically to rehoming organisations in the UK and US from February 2016-July 2017. Of 73 respondents, the majority conducted assessments for all dogs. Using a thematic analysis, nine themes and 71 sub-themes emerged concerning the types of information respondents aim to gather from assessments. The majority of respondents used, at least partially, pass/fail scoring, i.e., certain outcomes would lead to dogs being deemed unadoptable. Forty-one sub-themes and one theme were identified as potentially leading to a dog being deemed unadoptable. The evidence base for these factors was identified from the scientific literature relating to: increased risk for relinquishment, impact on a dog's quality of life, and human safety risk. Evidence supported 10 factors: "aggression towards people", "aggression towards cats or other animals", "aggression towards dogs", "biting or snapping", "resource guarding", "activity level or exercise needs", "destructiveness", "housetrained", "fearfulness", and "knowledge of basic commands and/or general training". Of those, seven were associated only with relinquishment risk, two ("resource guarding", "knowledge of basic commands") with human safety risk, and one ("fearfulness") with both. Thus, for >85% of characteristics organisations deemed important for dogs' adoptability, scientific evidence to support this is lacking. More research is needed to investigate the value of behaviour assessments, especially concerning the assessment of factors that could pose a public safety risk. However, given the current lack of scientific support for many decisions regarding dogs' rehoming suitability and recognised pressure on resources, it is suggested that organisations should focus on pre-adoption adopter education and post-adoption support., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Griffin, John, Pike and Mills.)

Mental health problems and suicide are more frequent in autistic adults than general population. Dog ownership can improve human well-being. This study aimed to generate a framework of well-being outcomes for dog-related activities in autistic adults and compare it to the framework generated for a general adult population. Thirty-six autistic dog owners (18-74 years old, 18 males) from diverse UK regions were interviewed and transcripts thematically analysed. 16.7% reported that their dogs prevented them from taking their own lives, mainly due to the dog's affection and the need to care for the animal. Close dog-owner interactions (e.g., cuddling, walking, dog's presence) were the most frequent activities improving emotions/moods and life functioning, whereas routine-like activities (e.g., feeding the animal) particularly enhanced life functioning. Well-being worsening was mainly linked to dog behaviour problems, dog poor health/death and obligations to the dog. Despite some negatives associated with ownership, having a dog could improve the well-being of many autistic adults and assist suicide prevention strategies in this high-risk group. The framework was consistent with that generated previously, indicating its robustness and the potential opportunity to focus on dog-related activities rather than the vague concept of "ownership" when considering the impact of ownership on well-being., (© 2021. The Author(s).)

Cross-sectional comparisons of well-being between dog owners and non-owners commonly generate inconsistent results. Focusing on the uniqueness of the relationship might help address this issue and provide a stronger foundation for dog-related psychotherapeutic interventions. This study aims to evaluate the impact of dog-related activities (e.g., exercising the dog) on owner hedonic well-being, life satisfaction and eudaimonic well-being. It was also hypothesised that psychological closeness to the dog would affect these well-being outcomes. For this study, 1030 dog owners aged over 18 years old answered an online questionnaire about the impact of 15 groups of dog-related activities on their well-being. Ordinal regressions were used to estimate the mean response (and its uncertainty) for each outcome, while conditioning for psychological closeness to the dog and controlling for several key covariates. Tactile interactions and dog playing were significantly more beneficial than other activities for hedonic well-being, and dog training and dog presence for eudaimonic well-being. In contrast, dog health issues and behavioural problems were linked to decrements in these well-being outcomes. Higher psychological closeness to the dog predicted greater improvement in well-being in positive dog-related activities. Our quantitative study validates the general findings of previous qualitative work and lays the groundwork for future longitudinal studies.

Frustration is a negative emotional state implicated in a range of canine behaviour problems. The Canine Frustration Questionnaire (CFQ) is the first psychometric tool developed to assess frustration tendencies in dogs based on owner report. However, to date, no published studies have assessed behavioural and physiological correlates of this trait. A novel behaviour test battery was developed to induce frustration in dogs, mapping onto the CFQ. Forty-four dogs were recruited and filmed whilst undertaking the test battery, and a CFQ was completed by each owner. Targeted behavioural measures were assessed from this footage, based on hypotheses aimed at evaluating convergent and discriminant validity with facets of the CFQ. In addition, a saliva sample was collected pre- and post-testing for 39 dogs, and a cortisol assay performed using ELISA to provide a physiological measure of arousal. A range of predicted behavioural test measures (e.g., vocalising and lunging) positively correlated with CFQ scores. For 22 dogs with pre-test salivary cortisol levels of <4 ng/mL (indicative of normal arousal at baseline), cortisol change and post-test cortisol levels positively correlated with the CFQ PC5 'Frustration coping' score. These results provide further evidence of the validity of frustration tendencies as measured by owner report through the CFQ.

Despite the abundance of studies investigating the benefits of having a dog, the specific aspects of dog ownership that impacts human well-being are not well understood. This study used a qualitative approach to create a framework of the main dog-related activities perceived by Brazilian owners to impact their well-being and compared the findings with those of a similar study in England. Thirty-two Brazilian dog owners from the five regions of the country were remotely interviewed. The thematic analysis of the transcripts generated a total of 58 dog-related activities, organised into 13 themes. Most activities were reported to have a positive effect on participants' well-being, accounting for 76.8% of the total number of mentions in the interviews. 'Playing with dog' and 'Dog presence' were the themes most frequently associated with positive well-being outcomes, whereas 'Unwanted behaviours' and 'Failing to meet dog's needs' were the most commonly associated with negative outcomes. The dog-related activities reported by Brazilian dog owners and the well-being outcomes linked to those activities were consistent with the previous British sample in the framework that emerged. These findings suggest reliability between the two methods used to gather data (remote interview versus focus group) and, most importantly, provide consistent cross-cultural evidence for how certain activities impact dog owner's well-being.

Leash pulling is a concern for dog owners and can be detrimental to the health and welfare of dogs. Neck-collars and back-connection harnesses are popular restraint types. Harnesses have been proposed as a better and more considerate option for canine health and welfare. Anecdotally, dogs pull more when wearing a back-connection harness; however, there is no scientific evidence for this perception. This study aimed to investigate how strongly dogs pull on the lead to achieve a food treat or toy under restraint by a neck-collar versus a back-connection harness. A within-subject counterbalanced design was used for the study, involving 52 shelter dogs. A customised canine leash tension metre was connected to the collar or harness to record the pulling of the dogs, including measuring the maximal and mean leash tension, and the time spent pulling. In addition, dog behaviours were recorded using two cameras from two separate directions. The maximal and mean leash tension and the pulling time were greater under restraint by harness when attracting dogs with food treats. No significant difference between harness and collar was found in potential stress-related behaviours (e.g. tail and ear positions, lip-licking, and panting). However, dogs looked at the experimenter more often when restrained by harness than collar in the food treat attraction test. No significant difference was detected between harness and collar with respect to leash tension and stress-related behaviours in the toy attraction test. These findings suggest that dogs tend to pull stronger and more steadily when wearing a back-connection harness compared to a neck collar to reach the food treat but not the toy., Competing Interests: MP is employed as the principal scientist by RSPCA, Qld. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Shih, Phillips, Mills, Yang, Georgiou and Paterson.)

Play in domestic cats has been largely studied using a contextual approach, i.e., with a focus on what the cat is playing with, such as an object, itself or another cat. Such classification may be superficially attractive scientifically but it limits the ability to investigate function. We propose consideration of a psychobiological approach, which increases attention on hypotheses about the motivational and emotional state of the actors, may be more valuable. This may be particularly important in the case of intercat exchanges that might involve play, for example when one cat may chase another which does not want to be chased, the general interaction should not be considered playful. Key to improving the scientific study of such interactions is the need to adopt a common terminology, thus we synthesise a common ethogram from the published literature. Secondly at the heart of a psychobiological approach is a consideration of both the affective state and motivational goal of each actor in an interaction, since they may not be congruent, and recognition of the hypothetical nature of any such functional classification. However, this bottom up approach provides valuable insights that can be tested. We argue that when one cat treats another as an object or prey, such activity relates to the former cat seeking to learn about its own skills in relation to manipulating its physical environment (prey are not considered part of the complex social relationships and thus social environment of an individual). However, when interaction between cats is reciprocal it may function to facilitate social learning and may be best described as mutual social play. It needs to be recognised that interactions are dynamic and thus our classification of a situation needs to be flexible. So mutual social play may turn into a form of non-reciprocal interaction. We conclude by outlining priorities for future research to help us improve our ability to answer the question "Are these cats playing?" in a wider range of contexts., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Gajdoš Kmecová, Pet'ková, Kottferová, Skurková and Mills.)

Background: Companion animals may be a positive presence for their owners during the COVID-19 pandemic. However, the welfare of a companion animal is strongly influenced by the behaviour of their owners, as well as their physical and social environment. We aimed to investigate the reported changes in companion animal welfare and behaviour and to examine the association between these changes and companion animal owners' mental health., Methods: A cross-sectional online survey of UK residents over 18 years of age was conducted between April and June 2020 (n = 5926). The questionnaire included validated, bespoke items measuring outcomes related to mental health, human-animal bonds and reported changes in animal welfare and behaviour. The final item of the survey invited open-ended free-text responses, allowing participants to describe experiences associated with human-animal relationships during the first UK lockdown phase., Results: Animal owners made up 89.8% of the sample (n = 5323), of whom 67.3% reported changes in their animal's welfare and behaviour during the first lockdown phase (n = 3583). These reported changes were reduced to a positive (0-7) and negative (0-5) welfare scale, following principal component analysis (PCA) of 17 items. Participants reported more positive changes for cats, whereas more negative changes were reported for dogs. Thematic analysis identified three main themes relating to the positive and negative impact on companion animals of the COVID-19 pandemic. Generalised linear models indicated that companion animal owners with poorer mental health scores pre-lockdown reported fewer negative changes in animal welfare and behaviour. However, companion animal owners with poorer mental health scores since lockdown reported more changes, both positive and negative, in animal welfare and behaviour., Conclusion: Our findings extend previous insights into perceived welfare and behaviour changes on a very limited range of species to a wider range of companion animals. Owner mental health status has a clear, albeit small, effect on companion animal welfare and behaviour.

Cats form close emotional relationships with humans, yet little is known about this. This study characterized different types of relationship that cats might establish with their owners. Data were analyzed from 3994 responses to a questionnaire developed using expressions of social support and attachment in relation to everyday cat-owner interactions. Principal component analysis reduced the items to four factors: the "owner's emotional investment in the cat", "cat's acceptance of others", "cat's need for owner proximity" and "cat's aloofness". Cluster identified three groups of owners with two of these each sub-divided into two. The "open relationship bond" was characterized by a lightly emotionally invested owner and an avoidant cat. The "remote association" and "casual relationship" were characterized by an emotionally remote owner but differed in the cat's acceptance of others. The "co-dependent" and "friendship" relationship were characterized by an emotionally invested owner but differed in the cat's acceptance of others and need to maintain owner proximity. In conclusion, as with any complex social relationship, the type of cat-owner bond that develops is the product of the dynamic that exists between both the individuals involved, along with certain personality features, of which, the wider sociability of the cat and owner expectations may be particularly important.

Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Domestication has greatly changed the social and reproductive behavior of dogs relative to that of wild members of the genus Canis, which typically exhibit social monogamy and extended parental care. Unlike a typical gray wolf pack that consists of a single breeding pair and their offspring from multiple seasons, a group of free-ranging dogs (FRDs) can include multiple breeding individuals of both sexes. To understand the consequences of this shift in reproductive behavior, we reconstructed the genetic pedigree of an FRD population and assessed the kinship patterns in social groups, based on genome-wide single-nucleotide polymorphism genotypes. Consistent with behavioral observations, the mating system of the study population was characterized by polygynandry. Instead of the discreet family units observed in wolves, FRDs were linked by a network of kinship relationships that spread across packs. However, we also observed reproduction of the same male-female pairs in multiple seasons, retention of adult offspring in natal packs, and dispersal between neighboring packs-patterns in common with wolves. Although monogamy is the predominant mating system in wolves, polygyny and polyandry are occasionally observed in response to increased food availability. Thus, polygynandry of domestic dogs was likely influenced by the shift in ecological niche from an apex predator to a human commensal., (© The Author(s) 2021. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology.)

The inner brow raiser is a muscle movement that increases the size of the orbital cavity, leading to the appearance of so-called 'puppy dog eyes'. In domestic dogs, this expression was suggested to be enhanced by artificial selection and to play an important role in the dog-human relationship. Production of the inner brow raiser has been shown to be sensitive to the attentive stance of a human, suggesting a possible communicative function. However, it has not yet been examined whether it is sensitive to human presence. In the current study, we aimed to test whether the inner brow raiser differs depending on the presence or absence of an observer. We used two versions of a paradigm in an equivalent experimental setting in which dogs were trained to expect a reward; however, the presence/absence of a person in the test apparatus was varied. In the social context, a human facing the dog delivered the reward; in the non-social context, reward delivery was automatized. If the inner brow raiser has a communicative function and dogs adjust its expression to an audience, we expect it to be shown more frequently in the social context (when facing a person in the apparatus) than in the non-social context (when facing the apparatus without a person inside). The frequency of the inner brow raiser differed between the two contexts, but contrary to the prediction, it was shown more frequently in the non-social context. We further demonstrate that the inner brow raiser is strongly associated with eye movements and occurs independently in only 6% of cases. This result challenges the hypothesis that the inner brow raiser has a communicative function in dog-human interactions and suggests a lower-level explanation for its production, namely an association with eye movements., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Bremhorst, Mills, Stolzlechner, Würbel and Riemer.)