Assessing equine emotional state

The impact of restricted grazing systems on the behaviour and welfare of ponies

BACKGROUND

Equine obesity is a growing concern. Much of the current management advice centres on dietary restrictions, including the removal or limitation of grazing. Little is known about the impact of these approaches on the welfare of the horse.

OBJECTIVE

This study investigates the effect of two commonly used grazing systems advocated for the control of weight-the 'strip-grazing' and the 'track' systems-on the behaviour and welfare of outdoor-living ponies.

STUDY DESIGN

A within-subject cross-over experimental design with four groups of pasture-kept ponies experiencing each system for 4 weeks in a random order.

METHODS

Time budgets and behavioural indicators of welfare were measured using 24-h electronic surveillance, morphometric parameters including weight, body condition score and cresty neck score were measured weekly and activity levels were tracked. The effect of grazing system on movement and behaviour was tested using a general linear model.

RESULTS

Ponies moved more [median (IQR) % time spent moving, track: 3.23% (2.08%), strip: 2.02% (0.90%); p = 0.001] and travelled a greater distance [median (IQR) metres/24 h, track: 7013.47 m (1761.49 m), strip: 5331.91 m (494.16 m); p < 0.001] and engaged in less overt agonistic behaviour on the track system compared with the strip system [median (IQR) prevalence per hour; track: 0.14 (0.30), strip: 0.21 (0.37) p = 0.02].

MAIN LIMITATIONS

A relatively short time period of exposure to each grazing system.

CONCLUSIONS

Ponies on strip systems moved less and exhibited increased agonistic interactions compared with the track system, maybe as a result of a perceived reduction in space or concentration of resources, although the accessible areas were matched. These results suggest that there may be physical as well as psychological health benefits to the track system.

Horse Sector Participants' Attitudes towards Anthropomorphism and Animal Welfare and Wellbeing

Anthropomorphizing can misinform the making of inferences about animal mental experiences. This is a consideration when implementing the Five Domains Model for animal welfare assessment. An online survey run in 2021 captured horse sector participants' perspectives about anthropomorphism and wellbeing in relation to horses. Most respondents, 82.9% (n = 431/520), believed that anthropomorphism could influence horse welfare and wellbeing. These respondents were then asked how, in their opinion, anthropomorphism might relate to horse welfare. A thematic analysis identified two themes: (1) 'Anthropomorphism can influence how people relate to horses' and (2) 'Anthropomorphism can have consequences for horse welfare and wellbeing'. The results suggested that experienced respondents were aware of the complexities surrounding anthropomorphic attitudes and that anthropomorphism can have beneficial and detrimental consequences on horse welfare and wellbeing. Benefits include a sense of relatedness to a horse, while detriments include the potential to misinterpret horse behaviors. The authors propose that anthropomorphism has a place in horse welfare and wellbeing when used critically and with caution. This study recommends that there is a need to actively manage anthropomorphism when organizations update policies and practices and implement the Five Domains Model. More research is required to understand the effects of anthropomorphism on horse-related practices.

"How long is life worth living for the horse?" A focus group study on how Austrian equine stakeholders assess quality of life for chronically ill or old horses

BACKGROUND

Quality of life (QoL) provides a comprehensive concept underpinning veterinary decision-making that encompasses factors beyond physical health. It becomes particularly pertinent when seeking responsible choices for chronically ill or old horses that emphasise their well-being and a good QoL over the extension of life. How different stakeholders use the concept of QoL is highly relevant when considering the complexity of these decisions in real-life situations.

METHODS

Seven focus group discussions (N = 39) were conducted to gain insights into how stakeholders assess and use equine QoL in veterinary care decisions for chronically ill and/or old horses. The discussions included horse owners (n = 17), equine veterinarians (n = 7), veterinary officers (n = 6), farriers (n = 4), and horse caregivers (n = 5). The combination of deductive and inductive qualitative content analysis of the group discussions focused on identifying both similarities and differences in the views of these groups regarding QoL for old and/or chronically ill horses.

RESULTS

Findings show agreement about two issues: the importance of the individuality of the horse for assessing QoL and the relevance of QoL in making decisions about veterinary interventions. We identified differences between the groups with respect to three issues: the time required to assess QoL, stakeholders' contributions to QoL assessments, and challenges resulting from those contributions. While owners and caregivers of horses emphasised their knowledge of a horse and the relevance of the time they spend with their horse, the veterinarians in the study focused on the differences between their own QoL assessments and those of horse owners. In response to challenges regarding QoL assessments and decision-making, stakeholders described different strategies such as drawing comparisons to human experiences.

CONCLUSIONS

Differences between stakeholders regarding equine QoL assessments contribute to challenges when making decisions about the care of chronically ill or old horses. The results of this study suggest that individual and collaborative reflection about a horse's QoL should be encouraged, for example by developing practicable QoL assessment tools that support relevant stakeholders in this process.

Exploring the relationship between horse-owner attributes and their approach to horse training

The way horses are trained has implications for equine welfare and training success, yet little is known about the factors that influence horse-owners' choice of training approach (TA). Limited understanding in this area will hinder the development and dissemination of evidence-based training advice to owners. Consequently, this study aims to identify demographic and attitudinal factors that influence horse-owner TA selection. A 22-question online survey collected information from 1,593 horse-owners about their demographics, equestrian activities, goals and beliefs. Participants rated how likely they were to use six different horse TAs on a five-point scale. Multinomial regression analysis and Spearman's correlation coefficients were used to identify factors associated with their likelihood of using each TA. Several factors were associated with reported TA use, including age, gender identity, goals, activities, industry role and whether they had training in animal behavior. Beliefs about equine sentience, cognitive ability and whether science should inform horse training correlated with likelihood of applying aversives. This study provides insight for further research and development of educational strategies to reduce the use of training approaches that may compromise equine welfare.

Attention bias and novel object test in rams (Ovis aries) under intensive farming

Affective states are long lasting mood states resulting from an accumulation of experiences. The knowledge of the affective state of animals can significantly help maintain and/or increase animal welfare. The aim of the study was to recognize the affective state of 13 adult rams reared under an intensive system and to further associate their affective state with hierarchy, sociability order and maintenance and social behaviour. The affective state was estimated by exposing them to an attention bias test and two novel object tests. Individuals with negative affective states performed reduced head hanging (p = 0.014), reduced agonistic behaviour (p = 0.033), increased social proximity (p = 0.009) and received less affiliative behaviours (p = 0.006). The study estimated the affective state of the rams and indicated easily recognizable maintenance and social behaviours correlated with negative affective state. Such behaviours could increase the awareness of the animals' welfare and thus improve management practices.

Horses discriminate between human facial and vocal expressions of sadness and joy

Communication of emotions plays a key role in intraspecific social interactions and likely in interspecific interactions. Several studies have shown that animals perceive human joy and anger, but few studies have examined other human emotions, such as sadness. In this study, we conducted a cross-modal experiment, in which we showed 28 horses two soundless videos simultaneously, one showing a sad, and one a joyful human face. These were accompanied by either a sad or joyful voice. The number of horses whose first look to the video that was incongruent with the voice was longer than their first look to the congruent video was higher than chance, suggesting that horses could form cross-modal representations of human joy and sadness. Moreover, horses were more attentive to the videos of joy and looked at them for longer, more frequently, and more rapidly than the videos of sadness. Their heart rates tended to increase when they heard joy and to decrease when they heard sadness. These results show that horses are able to discriminate facial and vocal expressions of joy and sadness and may form cross-modal representations of these emotions; they also are more attracted to joyful faces than to sad faces and seem to be more aroused by a joyful voice than a sad voice. Further studies are needed to better understand how horses perceive the range of human emotions, and we propose that future experiments include neutral stimuli as well as emotions with different arousal levels but a same valence.

Horse behavior and facial movements in relation to food rewards

Food rewards are believed to have a positive valence in horses. The aim of this study was to assess the effect of food rewards on horse behavior before entering a horse chute, and behavior and facial movements while restrained in it. Thirteen female adult horses were brought once daily to an animal handling facility for three weeks. In week 1, baseline period, no reinforcement was applied. In weeks 2 and 3, experimental phase, half of the horses received positive reinforcement treatment after entering and remaining in the chute; the remaining horses were considered as controls (no positive reinforcement applied). There was a cross-over between the groups during the experimental phase. Horses were individually brought to the restraining chute and videos recorded during 60-sec. The duration and number of entries into the area close to the gate leading to the chute were measured before restraining and body posture, neck position, and tail swinging were recorded in the chute. Facial movements were also recorded and scored using EquiFACS methodology. Multilevel linear and logistic models were built to assess behavioral changes from baseline to the treatment phase and between phases (control and positively reinforced). Horses did not change their body posture or tail swings across the different phases (P > 0.1) and were less likely to show lowered neck during the positively reinforced phase (OR: 0.05; CI95%: 0.00-0.56; P = 0.05) compared to baseline. The likelihood of a lowered neck did not differ between the positive reinforcement and control phases (P = 0.11). In the positively reinforced phase, horses seemed to be more attentive (ears forward) and active (less eye closures, more nose movements) than in the control phase. A three-day positive reinforcement phase did not elicit major changes in body behavior in the chute but affected the facial movements of group-housed mares.

Equine Social Behaviour: Love, War and Tolerance

Sociality is an ethological need of horses that remained unchanged by domestication. Accordingly, it is essential to include horses' social behavioural requirements and the opportunity to establish stable affiliative bonds in equine management systems and welfare assessment. Thus, this systematic review aims to provide an up-to-date analysis of equine intraspecific social ethograms. A literature review yielded 27 papers that met the inclusion criteria by studying adult (≥2 years) equine social behaviour with conspecifics using a well-defined ethogram. Social interactions were observed in 851 horses: 320 (semi-)feral free-ranging, 62 enclosed (semi-)feral and 469 domesticated, living in groups averaging 9.1 (mean +/- 6.8 s.d., range: 2-33) horses. The ethograms detailed in these 27 studies included a total of 40 (mean: 12.8/paper, range: 2-23) social behaviours, of which 60% (24/40) were agonistic, 30% (12/40) affiliative, 7.5% (3/40) investigative and 2.5% (1/40) neutral. The 27 publications included 67.7% agonistic and only 26% affiliative, 5.1% investigative and 1.2% neutral social behaviours in their methodology, thus focusing predominantly on socio-negative interactions. The strong emphasis on agonistic behaviours in equine ethology starkly contrasts with the rare occurrence of agonistic behaviours in stable horse groups and the well-established importance of affiliative interactions for equine welfare. The nuanced and complex equine social behaviour requires refinement of the ethogram with a greater focus on affiliative, ambivalent and indifferent interactions and the role of social tolerance in equine social networks to advance equine welfare assessment.

A Pilot Study on Behavioural and Physiological Indicators of Emotions in Donkeys

Recognizing animal emotions is critical to their welfare and can lead to a better relationship with humans and the environment, especially in a widespread species like the donkey, which is often prone to welfare issues. This study aims to assess the emotional response of donkeys through an operant conditioning task with two presumed different emotional contents. Specifically, a within-subject design including positive and negative conditions was conducted, collecting behavioural and physiological (heart rate variability and HRV) parameters. Facial expressions, postures, and movements were analysed by principal component analysis and behavioural diversity indexes (frequencies, activity budgets, richness, Shannon and Gini-Simpson). During the positive condition, both ears were held high and sideways (left: r = -0.793, p < 0.0001; right: r = -0.585, p = 0.011), while the ears were frontally erected (left: r = 0.924, p < 0.0001; right: r = 0.946, p < 0.0001) during the negative one. The latter was also associated with an increased tendency to walk (r = 0.709, p = 0.001), walk away (r = 0.578, p = 0.012), more frequent changes in the body position (V_{Body position} = 0, p = 0.022), and greater behavioural complexity (V_{Gini-Simpson Index} = 4, p = 0.027). As for HRV analysis, the root mean square of successive beat-to-beat differences (rMSSD) was significantly lower after the negative condition. These non-invasive parameters could be considered as possible indicators of donkeys' emotional state.

The Effect of Stabling Routines on Potential Behavioural Indicators of Affective State in Horses and Their Use in Assessing Quality of Life

Increasing interest in equine welfare has emphasised the need for objective and reliable behavioural indicators of horses’ affective state. However, research has yielded mixed results regarding behaviours suited for industry use largely because they are subject to anthropomorphic interpretation. Stabling is commonly used to manage domesticated horses despite research indicating that it can negatively impact horse welfare, but its effect on their affective state is yet to be quantified. Ten adult horses (11.8 ± 4.4 years) were observed either on a day- (DS) or night-stabling (NS) schedule over two consecutive 24 h periods. NS horses were kept confined for significantly longer (13.60 ± 0.04 h) than DS horses (7.73 ± 0.07; t7 = 5.70; p = 0.0004). Eight behaviours occurred significantly more often during NS than DS: forward ears (t7 = 3.32; p = 0.001), neutral ears (t7 = 3.47; p = 0.001), stepping forward (t7 = 2.62; p = 0.001), stepping laterally (t7 = 2.39; p = 0.001), sternal recumbency (t7 = 2.64; p = 0.001), yawning (t7 = 2.69; p = 0.001), non-nutritive chewing (t7 = 2.49; p = 0.001), and closing eyes (t7 = 2.71; p = 0.001). These behaviours may be candidates for indicators that can be used to determine the affective state in horses and subsequently be used to assess equine quality of life and to optimise individual horse welfare.

Donkey Heart Rate and Heart Rate Variability: A Scoping Review

Heart rate (HR) and heart rate variability (HRV) are commonly used physiological measures in animals. While several studies exist on horse HRV, less information is available for donkeys. This scoping review aims to understand the extent and type of published evidence on donkey HR and HRV, their clinical and research applications, the devices used, and the analysis performed. Only quantitative primary studies published in English were considered. Four different databases were queried through the Web of Science platform, with additional evidence identified by citation chasing. After a two-stage screening phase, data were extracted considering study and population characteristics, information on HR/HRV analysis, and applications. The majority of the 87 included articles (about 80%) concerned a sample size of up to 20 individuals and were published since 2011 (about 65%). Forty-one articles employed an electronic device for signal acquisition (mainly electrocardiographs and heart rate monitors), yet only two articles reported HRV parameters. The literature on donkey HRV is lacking, and this gap can be filled by gaining knowledge on donkey characteristics and finding useful tools for welfare assessment. Comparison with what is known about the horse allows a discussion of the technical and interpretative difficulties that can be encountered with donkeys.

Variation of Physiological and Behavioural Parameters during the Oestrous Cycle in Mares

The behaviour of oestrous mares is well-known in horse breeding. However, alterations in their physiological and behavioural indices during the whole oestrous cycle are scarcely known. The objective of the study was to analyse changes in cardiac activity variables, rectal and superficial temperatures, behaviour towards humans and conspecifics, and the time of standing and locomotor activity in mares during their oestrous cycle. Fifteen adult mares in oestrus were examined in the morning and evening (six successive days) and in dioestrus (five days-once every third day). The oscillation of physiological and behavioural variables accompanies changes in mares' sexual behaviour. Most physiological variables studied in oestrus indicate the elevated activity of the adrenergic nervous system and, opposite to that, both behaviour towards humans and conspecifics and the time of standing relate to a relaxed state. The end of oestrus, manifested by a rapid decrease in most of the physiological variables studied, is followed by changes of behavioural variables at the beginning of dioestrus. The time of locomotor activity arises at the end of oestrus. The outcomes may contribute to the knowledge of, among others, mare owners who evaluate the oestrus by mares' sexual behaviours without regarding other rhythmically changing variables.

Going Deeper than Tracking: A Survey of Computer-Vision Based Recognition of Animal Pain and Emotions

Advances in animal motion tracking and pose recognition have been a game changer in the study of animal behavior. Recently, an increasing number of works go ‘deeper’ than tracking, and address automated recognition of animals’ internal states such as emotions and pain with the aim of improving animal welfare, making this a timely moment for a systematization of the field. This paper provides a comprehensive survey of computer vision-based research on recognition of pain and emotional states in animals, addressing both facial and bodily behavior analysis. We summarize the efforts that have been presented so far within this topic—classifying them across different dimensions, highlight challenges and research gaps, and provide best practice recommendations for advancing the field, and some future directions for research.

Can Ponies (Equus Caballus) Distinguish Human Facial Expressions?

Communication within a species is essential for access to resources, alerting to dangers, group facilitation and social bonding; human facial expressions are considered to be an important factor in one’s ability to communicate with others. Evidence has shown that dogs and horses are able to distinguish positive and negative facial expressions by observing photographs of humans, however there is currently no research on how facial expressions from a live human are perceived by horses. This study investigated how ponies distinguish facial expressions presented by live actors. Trained actors (n = 2), using the human Facial Action Coding System, displayed four facial expressions (anger, sadness, joy and neutral) individually to twenty ponies. Heart rate and behaviors of the ponies including first monocular eye look, eye look duration (right and left side bias) and latency to approach were observed. A generalized linear mixed model (GLIMMIX) using Sidak’s multiple comparisons of least squared means determined that when exposed to anger expressions ponies looked more often with their left eye first and when exposed to joy, looked more often with their right eye first (p = 0.011). The ponies spent more time looking at angry expressions (p = 0.0003) in comparison to other expressions. There was no variation in heart rate across expressions (p > 0.89). Regardless of human facial expression, ponies looked longer (p = 0.0035), took longer to approach (p = 0.0297) and displayed more oral behaviours (p < 0.0001) with one actor than the other indicating increased arousal or negative valence. Ponies with more experience as a lesson mount had lower heart rates (p < 0.0001) carried their head lower (p < 0.0001), kept their left ear on the actor (p < 0.03) and exhibited more oral behaviours (p < 0.0001) than ponies with less experience. This study demonstrates that ponies are able to distinguish facial expressions presented by a live human, but other factors also contribute to their responses to humans.

Selection of Image Texture Analysis and Color Model in the Advanced Image Processing of Thermal Images of Horses following Exercise

Simple Summary

Detecting horse state after exercise is critical for maximizing athletic performance. The horse’s response to fatigue includes exercise termination or exercise continuation at a lower intensity, which significantly limit the results achieved in races and equestrian competition. As conventional methods of detecting and quantifying exercise effort have shown some limitations, infrared thermography was proposed as a method of contactless detection of exercise effect. The promising correlation between body surface temperature and exercise-dependent blood biomarkers has been demonstrated. As the application of conventional thermography is limited by low specificity, advanced thermal image analysis was proposed here to visualize the link between blood biomarkers and texture of thermal images. Twelve horses underwent standardized exercise tests for six consecutive days, and both thermal images and blood samples were collected before and after each test. The images were analyzed using four color models (RGB, red-green-blue; YUV, brightness-UV-components; YIQ, brightness-IQ-components; HSB, hue-saturation-brightness) and eight texture-features approaches, including 88 features in total. In contrast to conventional temperature measures, as many as twelve texture features in two color models (RGB, YIQ) were linked with blood biomarker levels as part of the horse’s response to exercise.

Abstract

As the detection of horse state after exercise is constantly developing, a link between blood biomarkers and infrared thermography (IRT) was investigated using advanced image texture analysis. The aim of the study was to determine which combinations of RGB (red-green-blue), YUI (brightness-UV-components), YIQ (brightness-IQ-components), and HSB (hue-saturation-brightness) color models, components, and texture features are related to the blood biomarkers of exercise effect. Twelve Polish warmblood horses underwent standardized exercise tests for six consecutive days. Both thermal images and blood samples were collected before and after each test. All 144 obtained IRT images were analyzed independently for 12 color components in four color models using eight texture-feature approaches, including 88 features. The similarity between blood biomarker levels and texture features was determined using linear regression models. In the horses’ thoracolumbar region, 12 texture features (nine in RGB, one in YIQ, and two in HSB) were related to blood biomarkers. Variance, sum of squares, and sum of variance in the RGB were highly repeatable between image processing protocols. The combination of two approaches of image texture (histogram statistics and gray-level co-occurrence matrix) and two color models (RGB, YIQ), should be considered in the application of digital image processing of equine IRT.

The Effect of Rider:Horse Bodyweight Ratio on the Superficial Body Temperature of Horse's Thoracolumbar Region Evaluated by Advanced Thermal Image Processing

Appropriate matching of rider-horse sizes is becoming an increasingly important issue of riding horses' care, as the human population becomes heavier. Recently, infrared thermography (IRT) was considered to be effective in differing the effect of 10.6% and 21.3% of the rider:horse bodyweight ratio, but not 10.1% and 15.3%. As IRT images contain many pixels reflecting the complexity of the body's surface, the pixel relations were assessed by image texture analysis using histogram statistics (HS), gray-level run-length matrix (GLRLM), and gray level co-occurrence matrix (GLCM) approaches. The study aimed to determine differences in texture features of thermal images under the impact of 10-12%, >12 ≤15%, >15 <18% rider:horse bodyweight ratios, respectively. Twelve horses were ridden by each of six riders assigned to light (L), moderate (M), and heavy (H) groups. Thermal images were taken pre- and post-standard exercise and underwent conventional and texture analysis. Texture analysis required image decomposition into red, green, and blue components. Among 372 returned features, 95 HS features, 48 GLRLM features, and 96 GLCH features differed dependent on exercise; whereas 29 HS features, 16 GLRLM features, and 30 GLCH features differed dependent on bodyweight ratio. Contrary to conventional thermal features, the texture heterogeneity measures, InvDefMom, SumEntrp, Entropy, DifVarnc, and DifEntrp, expressed consistent measurable differences when the red component was considered.

How Happy Are Equine Athletes? Stakeholder Perceptions of Equine Welfare Issues Associated with Equestrian Sport

The international governing body for equestrian sports, the Fédération Equestre Internationale (FEI), states that the welfare of the horse must be paramount and never subordinated to competitive or commercial influences. However, there is growing unease about welfare issues from both within and outside the sport. The aim of this study was to understand stakeholder perceptions of current welfare issues within equestrian sport, determine whether there is scope for change, and explore attitudes towards welfare assessment. Participants (n = 48) from equestrian sport (n = 38) and animal welfare research (n = 10) attended a workshop that included welfare-related presentations and focus group sessions. The focus group sessions were recorded, anonymised and analysed using thematic analysis. Conflict between the demands of competition and the needs of the horse was identified as a key welfare challenge. Although the physical health of equine athletes is closely monitored, horses' psychological needs are sometimes overlooked. Participants recognised that improving competition practices may not be as impactful as improving the general management and training of horses. The term "quality of life" was considered preferable to "welfare", which had negative connotations. Participants appreciated the idea of incorporating formal welfare assessments into their training and competition plans but stated that existing tools are rarely used and are not deemed feasible for real-life conditions.

Nociceptive pain and anxiety in equines: Physiological and behavioral alterations

Pain and anxiety are two of the most important concerns in clinical veterinary medicine because they arise as consequences of multiple factors that can severely affect animal welfare. The aim of the present review was to provide a description and interpretation of the physiological and behavioral alterations associated with pain and anxiety in equines. To this end, we conducted an extensive review of diverse sources on the topic. The article begins by describing the neurophysiological pathway of pain, followed by a discussion of the importance of the limbic system in responses to pain and anxiety, since prolonged exposure to situations that cause stress and pain generates such physiological changes as tachycardia, tachypnea, hypertension, hyperthermia, and heart rate variability (HRV), often accompanied by altered emotional states, deficient rest, and even aggressiveness. In the long term, animals may show deficiencies in their ability to deal with changes in the environment due to alterations in the functioning of their immune, nervous, and endocrinologic systems. In conclusion, pain and anxiety directly impact the homeostasis of organisms, so it is necessary to conduct objective evaluations of both sensations using behavioral scales, like the horse grimace scale, complemented by assessments of blood biomarkers to analyze their correlation with physiological parameters: Heart rate, respiratory rate, HRV, theparasympathetic tone activity index, lactate and glucose levels, and temperature. Additional tools - infrared thermography, for example - can also be used in these efforts to improve the quality of life and welfare of horses.

Emotion Recognition in Horses with Convolutional Neural Networks

Creating intelligent systems capable of recognizing emotions is a difficult task, especially when looking at emotions in animals. This paper describes the process of designing a “proof of concept” system to recognize emotions in horses. This system is formed by two elements, a detector and a model. The detector is a fast region-based convolutional neural network that detects horses in an image. The model is a convolutional neural network that predicts the emotions of those horses. These two elements were trained with multiple images of horses until they achieved high accuracy in their tasks. In total, 400 images of horses were collected and labeled to train both the detector and the model while 40 were used to test the system. Once the two components were validated, they were combined into a testable system that would detect equine emotions based on established behavioral ethograms indicating emotional affect through the head, neck, ear, muzzle, and eye position. The system showed an accuracy of 80% on the validation set and 65% on the test set, demonstrating that it is possible to predict emotions in animals using autonomous intelligent systems. Such a system has multiple applications including further studies in the growing field of animal emotions as well as in the veterinary field to determine the physical welfare of horses or other livestock.

The Effect of Human-Horse Interactions on Equine Behaviour, Physiology, and Welfare: A Scoping Review

Simple Summary

Human–horse interactions (HHIs) are an important aspect of society, especially in the equine industry. HHIs are diverse and can be focused on horses as an economic means, pleasure, or companionship for humans. As a result, the welfare of horses during these interactions, including their mental and physical health, is an important consideration. Although the physical health of horses can be readily measured during equestrian activities, their mental health is more difficult to assess. This review was conducted to evaluate what is known about the horse’s mental state during common HHI in an attempt to better understand the welfare of the horse.

Abstract

Human–horse interactions (HHIs) are diverse and prominent in the equine industry. Stakeholders have an invested interest in making sure that HHIs are humane. Assessment of equine welfare goes beyond physical health and includes assessment of the emotional state of the animal. HHIs can have a permanent effect on human–horse relationships, thereby influencing welfare. Therefore, an understanding of the horse’s affective state during HHIs is necessary. A scoping review was conducted to: (1) map current practices related to the measurement of HHIs; (2) explore the known effects of HHIs on horse behaviour and physiology; and (3) clarify the connection between HHIs and equine welfare. A total of 45 articles were included in this review. Studies that used both physiological and behavioural measures of equine response to human interactions accounted for 42% of the included studies. A further 31% exclusively used physiological measures and 27% used behavioural observation. Current evidence of equine welfare during HHIs is minimal and largely based on the absence of a negative affective state during imposed interactions. Broadening the scope of methods to evaluate a positive affective state and standardization of methodology to assess these states would improve the overall understanding of the horse’s welfare during HHIs.

Spontaneous Behaviors of Post-Orchiectomy Pain in Horses Regardless of the Effects of Time of Day, Anesthesia, and Analgesia

This prospective and longitudinal study aimed to identify spontaneous post-orchiectomy pain behaviors in horses regardless of the effects of anesthesia, analgesia, and recording time of day. Twenty-four horses divided into four groups were submitted to: inhalation anesthesia only (GA), or combined with previous analgesia (GAA), or orchiectomy under pre (GCA), or postoperative (GC) analgesia. The data obtained from the subtraction of frequency and/or duration of 34 behaviors recorded during seven 60-min time-points in the 24 h after the anesthesia from those recorded in the mirrored time-points in the 24 h before the anesthesia (delta) were compared over time and among groups by Friedman and Kruskal-Wallis tests, respectively (p < 0.05). Time of day influenced the behaviors of walk, look out the window, rest the pelvic limb, and rest standing still. The only pain-related behaviors were decreased mirrored proportional differences in time spent drinking, and eating, and increased mirrored proportional differences in the frequency or duration of look at the wound, retract the pelvic limb, expose the penis, and look at the back of the stall. In conclusion, confounding factors rather than pain may influence several suggestive pain-related behaviors documented in the literature.

Equine-Assisted Interventions (EAIs) for Children with Autism Spectrum Disorders (ASD): Behavioural and Physiological Indices of Stress in Domestic Horses (Equus caballus) during Riding Sessions

Equine-assisted interventions (EAIs) are well-known complementary practices combining physical activity with emotional/cognitive stimulation. They are especially suited for children with autism spectrum disorders (ASD) who need a high degree of physical and psychological enrichment. Even though EAIs have become a common practice, stress responses in horses interacting with individuals that can manifest inappropriate behaviours, such as ASD children, have not been thoroughly investigated. Our multicentre study aimed to investigate behavioural and physiological indices of stress in horses involved in EAI standardised sessions with children with ASD compared to typically developing (TD) children. A controlled within-subject design with repeated measurements involving 19 horses and 38 children was adopted. Stress-related behaviours, heart rate, heart rate variability, and eye temperature were recorded during the riding sessions. Moreover, blood samples were collected from horses before and after each session to monitor changes in blood adrenocorticotropic hormone (ACTH), cortisol, and catecholamines. Results indicate that, in general, stress responses in horses involved in EAIs did not differ as a function of the horse being ridden by children with ASD or TD. A lower sympathetic tone in horses involved in ASD sessions was found, while in the mounting and dismounting phases, horses displayed behavioural signs of stress, independently from children's behaviour. We conclude that professionals working in EAI should increase their awareness of animal welfare and refine riding practices, taking into account horse's needs.

Social buffering in horses is influenced by context but not by the familiarity and habituation of a companion

Social buffering occurs when the presence of one animal attenuates another’s stress response during a stressful event and/or helps the subject to recover more quickly after a stressful event. Inconsistent previous results might reflect previously unrecognised contextual influences, such as the nature of the stimulus presented or social factors. We addressed these issues in a two-part study of horses paired with familiar (16 subjects) or unfamiliar (16 subjects) companions. Each subject performed 4 tests in a counterbalanced order: novel object test (static ball)—alone or with companion; and umbrella opening test—alone or with companion. Social buffering was significantly influenced by the nature of the stimulus presented, but not by companion’s habituation status or familiarity. Importantly, the stimulus used produced differential effects on behavioural and physiological measures of buffering. A companion significantly reduced behavioural response (reactivity) in the novel object test but not in the umbrella test. However, heart rate recovered more quickly for subjects with a companion in the umbrella test but not in the novel object test. We propose that circumstances which permit greater contextual processing may facilitate demonstration of behavioural effects of social buffering, whereas buffering in response to startling events may be manifest only during post-event physiological recovery.

Ethological and Physiological Parameters Assessment in Donkeys Used in Animal Assisted Interventions

BACKGROUND

Few studies have been performed to identify objective indicators for the selection of therapeutic donkeys or to assess their welfare during animal-assisted interventions (AAIs) Objective: This study aimed to evaluate the response to the ethological test and the modifications of physiological parameters in donkeys subjected to AAI sessions.

METHODS

Thirteen donkeys were subjected to a behavioral evaluation during an AAI session. Heart rate, heart rate variability, and root mean square of successive difference values were detected.

RESULTS

Statistically significant changes in the tested parameters were observed during AAI sessions.

CONCLUSIONS

In donkeys, there was a neurovegetative involvement during AAI sessions. Our data give a contribution to the evaluation of donkey welfare during AAIs.

The Potential of Human-Horse Attachment in Creating Favorable Settings for Professional Care: A Study of Adolescents' Visit to a Farm

Simple Summary

Although previous research has shown that the features of an attachment bond are fulfilled in human–dog dyads, it is still unclear if people may have horses as attachment figures. This paper examines whether adolescents’ contact with horses can result in attachment bonds and whether these forms of attachment hold any potential for motivating adolescents in professional care. The paper is based on a time-limited session where six girls and three boys, aged 16–17, were observing and interacting with free-roaming horses at a farm. The results suggest that the presence of horses may activate the development of attachment in adolescents in the same way people do. The four criteria of an attachment bond—proximity maintenance, safe haven, secure base, and separation distress—may be fulfilled in the interaction between a human and a horse. This promotes a therapeutically favorable environment for professional care that is appealing, unique, and accurate. The study provides insights into horses’ therapeutic potential in dealing with adolescents in need of professional therapy or care.

Abstract

Previous research has shown features of an attachment bond to be fulfilled in, for instance, human–dog dyads; however, there is a considerable lack of research on the potential attachment in human–horse relationships. Employing Bowlby’s criteria of an attachment bond and Pierce’s model of therapeutically powerful activity, this article studies whether short-term exposure to horses brings about elements of emerging attachment for adolescents and if this interaction holds potential in creating a favorable early-stage setting for professional care. It draws from group discussions carried out with nine 16–17-year-old adolescents who participated in an EASEL (Equine-Assisted Social and Emotional Learning) session when visiting a farm with a youth worker. A qualitative content analysis of the discussions revealed that some characteristics of the four principal criteria of an attachment bond—proximity maintenance, safe haven, secure base, and separation distress—were identifiable in the adolescents’ expressed experiences of observing and interacting with horses. Moreover, the three main sources of therapeutic power—appeal, accuracy, and intactness—intersected with the emerging development of the adolescents’ attachment to horses. Additionally, space for self-reflection was enhanced by the presence of the horses. The study offers insights into the potential of human–horse attachment in dealing with adolescents with and without special needs for various therapy and care purposes.

Naturalness and the Legitimacy of Thoroughbred Racing: A Photo-Elicitation Study with Industry and Animal Advocacy Informants

Simple Summary

The international thoroughbred industry is concerned about the public’s perception of racing. Therefore, the industry’s priorities are to address the publicly most visible and known welfare violations. However, common day-to-day racing practices also impact thoroughbred welfare. In this study, key industry informants and animal advocacy informants were interviewed to find out how they view common racing practices. For the interviews, photographs of thoroughbreds on race day were used, which the informants were asked to describe. Results show industry informants often naturalise, normalise, downplay or ignore the horses’ expressions, the impact of handling on the horse and the use of equipment. The animal advocacy informants tend to describe a horse whose nature is violated. In conclusion, the industry informants show limited interest in addressing common racing practices, and this places thoroughbred welfare at risk. Both groups of informants have different ideas about what is natural and what that means for thoroughbred welfare. With society’s understanding of welfare and of racing practices growing, the racing industry may be increasingly questioned about common racing practices. This article discusses the notion of naturalness in more detail and how it can be used to advance thoroughbred protection.

Abstract

The idea of what is natural has particular relevance in the thoroughbred racing and breeding discourse. It guides breeding regulations; influences how the thoroughbreds’ behaviour is perceived and has implications for husbandry, handling, training and racing practices. This study investigates how key industry and animal advocacy informants based in the US, Australia and the UK conceptualise naturalness within the context of common racing practices that potentially impact the horses’ welfare. The informants were interviewed using semi-structured interviewing and photo-elicitation. Four common images of thoroughbreds on race day were presented to elicit the informants’ responses. Differences emerged between how the two groups tended to describe the images and the role naturalness played in their conceptualisations. The findings were analysed using an updated version of the Layers of Engagement with Animal Protection developed by Bergmann to situate the informants’ conceptualisations of naturalness within the wider thoroughbred protection discourse. In conclusion, the industry informants tended to defend the status quo of common racing practices. They tended to naturalise and normalise these practices and downplay their welfare impact. This poses risks for thoroughbred welfare, which are amplified by misrepresentations of what is natural. With the public’s understanding of welfare and racing practices growing, racing’s legitimacy may be further questioned. Opportunities to leverage the potential of the notion of naturalness for thoroughbred protection are discussed.

Horses Could Perceive Riding Differently Depending on the Way They Express Poor Welfare in the Stable

This study investigated the relationships between four behavioral and postural indicators of a compromised welfare state in loose boxes (stereotypies, aggressive behaviors toward humans, withdrawn posture reflecting unresponsiveness to the environment, and alert posture indicating hypervigilance) and the way horses perceived riding. This perception was inferred using a survey completed by the usual riding instructor and during a standardized riding session (assessment of behaviors and postures, qualitative behavior assessment (QBA) and characterization of the horses' locomotion using an inertial measurement unit). In accordance with ear and tail positions and the QBA, stereotypic and the most hypervigilant horses in loose boxes seemed to experience a more negative affective state during the riding session compared with nonstereotypic and less hypervigilant animals (P < .02 in all cases). Horses which were aggressive toward humans in loose boxes had higher scores regarding the occurrence of discomfort and defensive behaviors on the survey than nonaggressive horses (P = .03). They also presented higher dorsoventral accelerations at a canter during the riding session (P = .03), requiring the rider to increase his spinal movement (P = .005). These results suggest that aggressive horses may be harder to ride than nonaggressive animals. The expression of unresponsiveness to the environment in loose boxes was related to more reluctance to move forward, as assessed in the survey (P = .006). This study suggests that a compromised welfare state in the stable is related to horses having a more negative perception of riding. This perception could vary depending on the expression of poor welfare.

The different hormonal system during exercise stress coping in horses

The review discusses the hormonal changes during exercise stress. The exercise generally produces a rise of adrenaline (A), noradrenaline (NA), adrenocorticotropic hormone (ACTH), cortisol, glucagon, growth hormone, arginine vasopressine, etc., and a drop of insulin. The hormonal events during reestablishment of homeostasis due to exercise stress can be divided into a catabolic phase, with decreased tolerance of effort, and reversible biochemical, hormonal and immunological changes, and an anabolic phase, with a higher adaptive capacity, and enhanced performance. The two main hormonal axes activated in the catabolic phase are sympathetic–adrenal–medullary system and hypothalamic-pituitary-adrenal (HPA) axis, while in the anabolic phase, growth hormone-insulin-like factor I axis, and gonadal axes. The hormonal responses during exercise and recovery can be regarded as regulatory and integrated endocrine responses. The increase of catecholamines and ACTH is dependent on the intensity of exercise; a marked increase in plasma A occurs during exercises with high emotional content. The response of cortisol is correlated with the duration of exercise, while the effect of exercise duration on b-endorphin changes is highly dependent on the type of exercise performed. Cortisol and b-endorphin changes usually occur in phase, but not during exercises with high emotional content. Glucocorticoids and iodothyronines are involved in meeting immediate energy demands, and a model of functional interactions between HPA axis and hypothalamic-pituitary-thyroid axis during exercise stress is proposed. A modulation of coping responses to different energy demanding physical activities required for sport activities could be hypothesized. This review supports the proposed regulation of hypophysiotropic TRHergic neurons as metabolic integrators during exercise stress. Many hormonal systems (ghrelin, leptin, glucose, insulin, and cortisol) are activated to control substrate mobilizations and utilization. The cardiovascular homeostasis, the fluid and electrolyte balance during exercise are highly dependent on vasoactive hormones (antidiuretic hormone, atrial natriuretic peptide, renin–angiotensin–aldosterone, and prostaglandins) control.

Differences in facial expressions during positive anticipation and frustration in dogs awaiting a reward

Facial expressions are considered sensitive indicators of emotional states in humans and many animals. Identifying facial indicators of emotion is a major challenge and little systematic research has been done in non-primate species. In dogs, such research is important not only to address fundamental and applied scientific questions but also for practical reasons, since many problem behaviours are assumed to have an emotional basis, e.g. aggression based on frustration. Frustration responses can occur in superficially similar contexts as the emotional state of positive anticipation. For instance, the anticipated delivery of a food reward may induce the state of positive anticipation, but over time, if the food is not delivered, this will be replaced by frustration. We examined dogs’ facial expressions in contexts presumed to induce both positive anticipation and frustration, respectively, within a single controlled experimental setting. Using DogFACS, an anatomically-based method for coding facial expressions of dogs, we found that the “Ears adductor” action was more common in the positive condition and “Blink”, “Lips part”, “Jaw drop”, “Nose lick”, and “Ears flattener” were more common in the negative condition. This study demonstrates how differences in facial expression in emotionally ambiguous contexts may be used to help infer emotional states of different valence.

Improving the Recognition of Equine Affective States

Simple Summary

People commonly fail to recognise the behavioural signs that horses display when they experience pain and fear. Consequently, the distress remains unresolved, reducing the horse’s welfare and having potential safety implications for the handler. In order to investigate the public’s ability to recognise such signs of equine distress, members of equestrian Facebook groups were asked to view and comment on six videos; these videos were selected by the authors on account of their portrayal of horses behaving in a manner suggestive of negative affect. For comparison, responses were also obtained from six equine behaviourists, who identified behaviours suggestive of varying degrees of distress. While respondents successfully recognised behaviour consistent with negative affect in some instances, videos featuring natural horsemanship and bridle-less riding were often wrongly interpreted to be positive experiences for the horses. Despite recognising behaviours indicative of distress in some videos, a minority of respondents nevertheless said they would have been happy for their own horse to be treated similarly. Participant age and experience had little effect on the results; however, responses by people who had selected “clicker training” as their preferred equestrian activity were more closely aligned with those of the equine behaviourists, suggesting that clicker trainers might be more accurate in their recognition of equine distress than other members of the equestrian community. This study can be used to inform the outreach activity of education and welfare organisations, through improved recognition, and subsequent reduction, of equine distress.

Abstract

A key welfare problem for horses is that people commonly fail to recognise, and consequently neglect to resolve, equine behavioural signs of distress, worsening the welfare of the horse and potentially putting the safety of the handler at risk as a result. Members of equestrian Facebook groups were asked to view six videos and assess the horse’s behaviour in each; the authors selected the videos and considered each video to demonstrate behaviour associated with negative affective states. An additional six equine behaviourists also completed the survey as an “expert comparison group” from whom we could define “correct” answers; their responses were consistent with each other and the views of the authors. Although the majority of respondents successfully recognised behaviour indicative of distress in some instances, behaviour associated with negative affective states was commonly missed; videos featuring natural horsemanship and bridle-less riding were particularly interpreted incorrectly to be positive experiences for the horses. Binary logistic regression analysis (72.1% success rate) confirmed that the different video types (ridden dressage, natural horsemanship, in-hand dressage, bridle-less riding, Western reining and behavioural rehabilitation) were strong predictors for obtaining a correct answer (p < 0.01) but that experience of equine-ownership was not. Of the equestrian activities preferred by participants, only proponents of clicker training showed an increased likelihood of obtaining the correct answer (p = 0.05). Even when behavioural signs suggestive of negative affective states were recognised, a minority of respondents stated that they would be happy for their horse to be treated similarly. In conclusion, behavioural signs of equine distress are poorly recognised; they therefore warrant an increased prominence in education and the outreach activity of welfare organisations, in order to reduce equine suffering.

Emotional Transfer in Human-Horse Interaction: New Perspectives on Equine Assisted Interventions

Equine assisted interventions (EAIs) include all therapeutic interventions aimed at improving human wellbeing through the involvement of horses. Due to the prominent emotional involvement traditionally characterizing their relation with humans, horses developed sophisticated communicative skills, which fostered their ability to respond to human emotional states. In this review, we hypothesize that the proximate causation of successful interventions could be human-animal mutual coordination, through which the subjects bodily and, most importantly, emotionally come into contact. We propose that detecting emotions of other individuals and developing the capacity to fine-tune one's own emotional states accordingly (emotional transfer mechanism), could represent the key engine triggering the positive effects of EAIs. We provide a comprehensive analysis of horses' socio-emotional competences according to recent literature and we propose a multidisciplinary approach to investigate this inter-specific match. By considering human and horse as a unique coupling system during the interaction, it would be possible to objectively measure the degree of coordination through the analysis of physiological variables of both human and animal. Merging the state of art on human-horse relationship with the application of novel methodologies, could help to improve standardized protocols for animal assisted interventions, with particular regard to the emotional states of subjects involved.

Social Learning in Horses-Fact or Fiction?

Prima facie, the acquisition of novel behaviors in animals through observation of conspecifics seems straightforward. There are, however, various mechanisms through which the behavior of animals can be altered from observing others. These mechanisms range from simple hard-wired contagious processes to genuine learning by observation, which differ fundamentally in cognitive complexity. They range from social facilitation and local enhancement to true social learning. The different learning mechanisms are the subject of this review, largely because research on learning by observation can be confounded by difficulties in interpretation owing to the looming possibility of associative learning infecting experimental results. While it is often assumed that horses are capable of acquiring new behavior through intra-species observation, research on social learning in horses includes a variety of studies some of which may overestimate the possession of higher mental abilities. Assuming such abilities in their absence can have welfare implications, e.g., isolating stereotypical horses on the assumption that these behaviors can be learned though observation by neighboring horses. This review summarizes the definitions and criteria for the various types of social transmission and social learning and reviews the current documentation for each type in horses with the aim of clarifying whether horses possess the ability to learn through true social learning. As social ungulates, horses evolved in open landscapes, exposed to predators and grazing most of the day. Being in close proximity to conspecifics may theoretically offer an opportunity to learn socially, however anti-predator vigilance and locating forage may not require the neural complexity of social learning. Given the significant energetic expense of brain tissue, it is likely that social facilitation and local enhancement may have been sufficient in the adaptation of equids to their niche. As a consequence, social learning abilities may be maladaptive in horses. Collectively, the review proposes a novel differentiation between social transmission (social facilitation, local, and stimulus enhancement) and social learning (goal emulation, imitation). Horses are undoubtedly sensitive to intra-species transfer of information but this transfer does not appear to satisfy the criteria for social learning, and thus there is no solid evidence for true social learning in horses.