Is it pain, or is it behaviour?

This year BVA Live will, for the first time, feature farm animal and equine CPD. Among the varied topics on offer, Gemma Pearson will be presenting an introduction to equine behavioural medicine, examining the link between emotional and physical health in horses.

Adaptive forgetting of place/object memory for dung in the domestic horse (Equus ferus caballus): Memory for a day.

The domestic horse (Equus ferus caballus) makes dung deposits to form "stud-piles" and compulsively examines dung droppings, suggesting that dung contains species-relevant information. The present study investigates horses' use of location (place), odor (object) and memory for dung sniff encounters. Horses were video recorded in 2 indoor and 4 outdoor riding arenas as they were taken at different time intervals to experimenter-determined objects or dung deposits that they could sniff. Frame-by-frame video analysis measured approaches, sniff duration, nostril use, ear position and blinking associated with dung investigation. Horses approached and sniffed dung-deposits for longer duration than non-dung objects in all test locations. They made head movements across the extent of dung-deposits when sniffing, showed no nostril or ear preference directed to the target, and blinked as they disengage from sniffing. Reduced approach probability and sniff duration showed that they displayed good place/object memory for dung previously visited at similar and different locations on the same day but poor memory for dung visited on a previous day. Adaptive forgetting of object/place memory for dung after a previous day's dung visit may optimizes risk assessment, including the possibility of premature interruption of foraging by conspecifics.

Horses' attentional characteristics differ according to the type of work.

Attention is a central process of cognition and influences the execution of daily tasks. In humans, different types of work require different attentional skills and sport performance is associated with the ability to attention shift. Attention towards humans varies in dogs used for different types of work. Whether this variation is due to the recruitment of individuals suitable for specific types of work, or to the characteristics of the work, remains unclear. In the present study, we hypothesized that domestic horses (Equus caballus) trained for different types of work would also demonstrate different attentional characteristics but we also explored other possible factors of influence such as age, sex and breed. We exposed more than sixty horses, working in 4 different disciplines, and living in two types of housing conditions, to a visual attention test (VAT) performed in the home environment. Individual attentional characteristics in the test were not significantly influenced by age, sex, breed or conditions of life but were strongly related to the type of work. Riding school horses showed longer sequences and less fragmented attention than all other horses, including sport horses living in the same conditions. Interestingly, sport performance was correlated with attention fragmentation during the test in eventing horses, which may need more attention shifting during the competitions. Working conditions may influence attention characteristics indirectly through welfare, or directly through selection and training. Our study opens new lines of thought on the determinants of animal cognition and its plasticity and constitutes a further step towards understanding the interrelationship between working conditions and cognition.

Relationship between anatomical characteristics and personality traits in Lipizzan horses.

We tested 35 Lipizzan horses older than 5 years, ridden and healthy in three behavioural tests (handling, fear-reaction, and target training test). Physiological (heart rate and heart rate variability) and anatomical measurements (120 head and body distances and angles) were collected to validate parameters that reliably inform on handling/cooperation, fear/exploration and trainability in horses. Utilizing a standard clustering methodology on the behavioural data, we identified four general types of responses and categorised an individual as intermediate, low fearful, horses with low cooperation or low trainability. We additionally analysed the head morphology following Tellington-Jones and Taylor recommendations and correlated the measurements with data from a horse personality questionnaire. Although allocation to a particular personality group was not associated with these two methods, these groups differed in six anatomical characteristics of head and body. Regardless of the group, our results indicated that shorter horses (<75.9 cm) with a wider muzzle (>10.5 cm) are trustworthy, less fearful and easier to handle and train. We also demonstrated that horses with stronger legs and a wider base of the head have a lower heart rate when exposed to the second trial of the handling test.

The effect of stress and exercise on the learning performance of horses.

Domestic horses are widely used for physically demanding activities but the effect of exercise on their learning abilities has not been explored. Horses are also frequently exposed to stressors that may affect their learning. Stress and exercise result in the release of glucocorticoids, noradrenaline and other neurotransmitters that can influence learning. It is not currently possible to directly measure concentrations of neurotransmitters in the brains of behaving horses, however the inference of neurobiological processes from peripheral markers have been widely used in studies of human cognition. We assigned 41 horses to either ridden exercise, uncontrollable stress or inactivity and evaluated their acquisition of an industry-style aversive instrumental learning task. Exercised horses achieved the learning criterion in the fewest number of trials compared to the stressed and inactive horses whose performance did not differ. The exercised horses' salivary cortisol concentrations decreased during learning whereas the concentrations of the other groups increased. Spearman's correlations revealed that horses with the highest cortisol concentrations required the most trials to reach the criterion. We present novel data that exercise prior to learning may enhance the acquisition of learning in horses. Conversely, activities that expose horses to uncontrollable stressors causing strong cortisol release may impair learning. It is proposed that these effects may be due to the influence of neurotransmitters such as cortisol and noradrenaline on brain regions responsible for learning.

Spaced training enhances equine learning performance.

This field experiment examined whether the well-documented benefit of spaced over massed training for humans and other animals generalizes to horses. Twenty-nine randomly selected horses (Equus ferus caballus) repeatedly encountered a novel obstacle-crossing task while under saddle. Horses were randomly assigned to the spaced-training condition (2 min work, 2 min rest, 2 min work, 2 min rest) or the massed-training condition (4 min work, 4 min rest). Total training time per session and total rest per session were held constant. Days between sessions (M = 3) were held as consistent as possible given the constraints of conducting research on a working ranch and safety-threatening weather conditions. During each training session, the same hypothesis-naïve rider shaped horses to cross a novel obstacle. Fifteen of 16 horses in the spaced-training condition reached performance criterion (94% success) while only 5 of 13 horses in the massed-training condition reached performance criterion (39% success). Horses in the spaced-training condition also initiated their first obstacle-crossing faster than horses in the massed-training condition and were faster at completing eight crossings than horses in the massed-training condition. Overall, task acquisition was higher for horses undergoing spaced training despite both groups experiencing the same total work and rest time per session. These findings generalize the learning-performance benefit observed in human spaced practice to horses and offer applied benefit to equine training.

Need or opportunity? A study of innovations in equids.

Debate persists over whether animals develop innovative solutions primarily in response to needs or conversely whether they innovate more when basic needs are covered and opportunity to develop novel behaviour is offered. We sourced 746 cases of "unusual" behaviour in equids by contacting equid owners and caretakers directly and via a website (https://innovative-behaviour.org), and by searching the internet platforms YouTube and Facebook for videos. The study investigated whether differences in need or opportunity for innovation were reflected in the numbers of different types of innovations and in the frequencies of repeating a once-innovative behaviour (i) with respect to the equids' sex, age, and breed type, (ii) across behavioural categories, and whether (iii) they were affected by the equids' management (single vs group housing, access to roughage feed, access to pasture, and social contact). We found that the numbers of different types of innovation and the frequency of displaying specific innovations were not affected by individual characteristics (sex, age, breed or equid species). Few types of innovation in escape and foraging contexts were observed, whilst the comfort, play, and social contexts elicited the greatest variety of innovations. We also found higher numbers of different types of innovations in horses kept in groups rather than in individual housing, and with unlimited rather than with restricted access to pasture and roughage. Equids in permanent social contact performed high rates of once-innovative behaviour. We suggest that equids produce goal-directed innovations and repeat the behaviour at high frequency in response to urgent needs for food and free movement or when kept in conditions with social conflict. However, equids devise the greatest variety of innovations when opportunity to play and to develop comfort behaviour arises and when kept in good conditions.

Horses show individual level lateralisation when inspecting an unfamiliar and unexpected stimulus.

Animals must attend to a diverse array of stimuli in their environments. The emotional valence and salience of a stimulus can affect how this information is processed in the brain. Many species preferentially attend to negatively valent stimuli using the sensory organs on the left side of their body and hence the right hemisphere of their brain. Here, we investigated the lateralisation of visual attention to the rapid appearance of a stimulus (an inflated balloon) designed to induce an avoidance reaction and a negatively valent emotional state in 77 Italian saddle horses. Horses' eyes are laterally positioned on the head, and each eye projects primarily to the contralateral hemisphere, allowing eye use to be a proxy for preferential processing in one hemisphere of the brain. We predicted that horses would inspect the novel and unexpected stimulus with their left eye and hence right hemisphere. We found that horses primarily inspected the balloon with one eye, and most horses had a preferred eye to do so, however, we did not find a population level tendency for this to be the left or the right eye. The strength of this preference tended to decrease over time, with the horses using their non-preferred eye to inspect the balloon increasingly as the trial progressed. Our results confirm a lateralised eye use tendency when viewing negatively emotionally valent stimuli in horses, in agreement with previous findings. However, there was not any alignment of lateralisation at the group level in our sample, suggesting that the expression of lateralisation in horses depends on the sample population and testing context.

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.

Gut microbiota resilience in horse athletes following holidays out to pasture.

Elite horse athletes that live in individual boxes and train and compete for hours experience long-term physical and mental stress that compromises animal welfare and alters the gut microbiota. We therefore assessed if a temporary period out to pasture with conspecifics could improve animal welfare and in turn, favorably affect intestinal microbiota composition. A total of 27 athletes were monitored before and after a period of 1.5 months out to pasture, and their fecal microbiota and behavior profiles were compared to those of 18 horses kept in individual boxes. The overall diversity and microbiota composition of pasture and control individuals were temporally similar, suggesting resilience to environmental challenges. However, pasture exposure induced an increase in Ruminococcus and Coprococcus that lasted 1-month after the return to individual boxes, which may have promoted beneficial effects on health and welfare. Associations between the gut microbiota composition and behavior indicating poor welfare were established. Furthermore, withdrawn behavior was associated with the relative abundances of Lachnospiraceae AC2044 group and Clostridiales family XIII. Both accommodate a large part of butyrate-producing bacterial genera. While we cannot infer causality within this study, arguably, these findings suggest that management practices maintained over a longer period of time may moderate the behavior link to the gut ecosystem beyond its resilience potential.

Aerial drone observations identified a multilevel society in feral horses.

The study of non-human multilevel societies can give us insights into how group-level relationships function and are maintained in a social system, but their mechanisms are still poorly understood. The aim of this study was to apply spatial association data obtained from drones to verify the presence of a multilevel structure in a feral horse society. We took aerial photos of individuals that appeared in pre-fixed areas and collected positional data. The threshold distance of the association was defined based on the distribution pattern of the inter-individual distance. The association rates of individuals showed bimodality, suggesting the presence of small social organizations or "units". Inter-unit distances were significantly smaller than those in randomly replaced data, which showed that units associate to form a higher-level social organization or "herd". Moreover, this herd had a structure where large mixed-sex units were more likely to occupy the center than small mixed-sex units and all-male-units, which were instead on the periphery. These three pieces of evidence regarding the existence of units, unit association, and stable positioning among units strongly indicated a multilevel structure in horse society. The present study contributes to understanding the functions and mechanisms of multilevel societies through comparisons with other social indices and models as well as cross-species comparisons in future studies.

Equine atypical myopathy: consumption of sycamore maple seedlings (Acer pseudoplatanus) by pastured horses is driven by seedling maturity and might be associated with phenolic compounds.

BACKGROUND: Poisoning with Acer pseudoplatanus L. in horses contradicts the hypothesis of coexistence between plants and vertebrate herbivores being mediated through antipastoral traits as toxins. However, incidental observations showed that horses evaded Acer seedlings with primary leaves. The objective of the present cross-discipline study was (i) to analyse whether developmental stages of A. pseudoplatanus L. differed as to phenolics hypothesised as antipastoral traits, and (ii) to observe systematically the selection behaviour of pastured horses towards A. pseudoplatanus seedlings. METHODS: Phenolic profiles of five developmental stages from fruits to seedlings of progressing age up to adult leaves of A. pseudoplatanus and Acer campestre L. were characterised. Video recordings of grazing behaviour of 29 pastured horses towards seedlings of A. pseudoplatanus resulted into 117 sequences as additional field data. RESULTS: The horses ingested 19.1 per cent of juvenile seedlings with cotyledons (1.65 mg total phenolics/g fresh weight (FW), 82 compounds, 0.02 mg total gallic acid/g FW) yet only 5.46 per cent of older seedlings with primary leaves (8.48 mg total phenolics/g FW, 120 compounds, 3.13 mg total gallic acid/g FW). CONCLUSION: Horses distinguished between seedlings in distinct stages that could be chemically distinguished, too. Acer seedlings with primary leaves provide a strong, but not complete antipastoral effect that correlates with dramatic changes in phenolic compounds.

Levelling playing field: synchronization and rapid facial mimicry in dog-horse play.

Social play is a window on cognitive and communicative abilities of species. Inter-specific play, in particular, is a fertile venue to explore the capacity to correctly perceive and interpret signals emitted by partners. Up to now, most studies have focussed on dog-human play due to the important implications such studies have in understanding the peculiar relationship we establish with our pets. Here, we focussed on social play between dogs and horses. By using a set of specific keywords (dog, horse, play, friend) we selected 20 videos of dog-horse social play (with each session lasting >30 s) from the open video-sharing website YouTube. We described the behavioural patterns composing each session by defining analogous and species-specific patterns shown by dogs and horses. The rates of self-handicapping and variability in playful actions did not differ between the two interacting subjects thus suggesting well-balanced playful tactics. The Relaxed Open Mouth (ROM, a widespread playful facial expression in mammals) was also similarly performed by dogs and horses. The Rapid Facial Mimicry (RFM) is an automatic, fast response in which individuals mimic others' expressions (less than 1 s) that seems to have a role in mood sharing during social interactions. The dogs and horses under study showed a stronger and rapid mimicry response (less than 1 s) after perceiving ROM than after perceiving an attempt to bite (a play pattern resembling ROM in its motor performance). Taken together, our results suggest that, despite the difference in size, the phylogenetic distance, and differences in the behavioural repertoire, dogs and horses are able to fine-tune their actions thus reducing the probability of misunderstanding and escalating into aggression. One of the future challenges is to explore the role of ontogenetic pathways and familiarity in shaping inter-specific communicative ability of animals that can be at the basis of a universal language of play.

Sniff, look and loop excursions as the unit of "exploration" in the horse (Equus ferus caballis) when free or under saddle in an equestrian arena.

Spontaneous locomotor behavior in a novel space reveals insights into an animal's world view or Umwelt. For example, in many animal species, spontaneous behavior in a novel environment is parsed into activities at a home base and excursions from the home base. Domestic horses (Equus ferus caballas) are frequently ridden for recreation or in performance events in an equestrian arena but there has been no description of horse behavior in an arena when they are unconstrained and "exploring" or when moving freely under saddle. The present examination of exploration provides insights into horse adaptive behavior more generally as well as insights into horse performance under saddle. Thoroughbred, American Quarter Horse and mixed-breed mares and geldings of various ages, with various degrees of training under saddle, and with varying familiarity with the arena were given 30-min tests in which they were at liberty to explore an equestrian arena. Additional 30-min tests were given in which horses explored the arena containing a tethered partner, or were ridden. Despite breed, sex, age and experience, behavior was similar. A horse spent most of its time near the entrance door of the area where it looked out, paced, and rolled. Periodic excursions formed loops. The outward leg of a loop was slow, often featured sniffing the ground, and ended with a head-raised, ears-forward look toward the far end of the arena. The homeward leg of a loop was made with lowered-head and ears-back and was relatively direct and fast. Successive loops could increase or decrease in size over a test period. If a partner was tethered at the far end of the area, a horse shifted its activity toward the partner. When horses under saddle were asked to make excursions into the arena but otherwise left unconstrained, they made loops, similar to that of freely moving horses. When ridden around the arena they returned more quickly to the near end of the arena than when leaving the near end of the arena. This organized home base/excursion behavior is discussed in relation to horse social structure and to its expression while under saddle.

Responses to death and dying: primates and other mammals.

Although some definitions of thanatology-broadly definable as the study of death and dying-exclude nonhumans as subjects, recognition of the scientific value of studying how other species respond to sick, injured, dying and dead conspecifics appears to be growing. And whereas earlier literature was largely characterized by anecdotal descriptions and sometimes fanciful interpretations, we now see more rigorous and often quantitative analysis of various behaviors displayed towards conspecifics (and sometimes heterospecifics) at various stages of incapacitation, including death. Studies of social insects in particular have revealed chemical cues that trigger corpse management behaviors, as well as the adaptive value of these behaviors. More recent research on other taxonomic groups (including aquatic and avian species, and mammals) has sought to better document these animals' responses to the dying and dead, to identify influencing factors and underlying mechanisms, and to better understand the physiological, emotional, social and psychological significance of the phenomena observed. This special issue presents original short reports, reviews, and full research articles relating to these topics in New World monkeys, Old World monkeys and apes, as well as equids and proboscids. The range of events, data, hypotheses and proposals presented will hopefully enrich the field and stimulate further developments in comparative evolutionary thanatology.

Feral horses' (Equus ferus caballus) behavior toward dying and dead conspecifics.

In the rapidly expanding field of comparative thanatology, reports from a wide range of taxa suggest that some aspects of a concept of death may be shared by many non-human species. In horses, there are only a few anecdotal reports on behaviors toward dead conspecifics, mostly concerning domestic individuals. Here, we describe the case of a 2-month-old, free-ranging male foal that died around 12 h after being found severely injured due to a presumed wolf attack, focusing on other individuals' reactions to the dying foal. We also placed camera traps near horse carcasses to investigate reactions by other horses. Kin and non-kin of both sexes showed unusual interest in the dying foal. However, horses appeared to avoid dead conspecifics. Recording individual reactions to dead and dying conspecifics in naturalistic settings will enhance our knowledge about death-related behaviors in horses, allowing comparisons with other species that have been more thoroughly studied, to understand the evolutionary basis of these behaviors.

Ile de Chypre - nobbles, jinks, and the ultrasonic sniper.

In this sensational case, it was alleged that after jinking unexpectedly and throwing its rider, racehorse Ile de Chypre, had been nobbled by an ultrasonic emitter concealed within a pair of binoculars. Ile de Chypre was 4-1 favourite at the King George V Handicap at Ascot on June 16, 1988 and a good distance away from the pack, a clear winner albeit for this alleged act of sensational intervention.

Effects of breed, management and personality on cortisol reactivity in sport horses.

Sport horses need to fulfill high physical and psychological requirements during training and competition. These as well as certain conditions of modern husbandry may affect their wellbeing. Here we aimed to (1) evaluate effects of demographic and management factors as well as personality traits on stress reactivity of sport horses, (2) investigate if elite sport horses have elevated stress levels compared to amateur sport horses, and (3) assess whether different equestrian disciplines differentially influence equine adrenal cortex responsiveness. For this purpose, we visited 149 healthy elite (n = 94) and amateur (n = 54) sport horses in Switzerland and performed an adrenocorticotropic hormone (ACTH) stimulation test. Additionally, a person who was familiar with the horse completed a questionnaire about demographic and management factors and their horses' personality traits. Linear models were calculated to assess associations between the questionnaire data and salivary cortisol 60 (T60) and 90 (T90) minutes after ACTH stimulation. While the model at T90 was not significant, post-stimulatory cortisol after 60 minutes appears most informative in line with a previous study and was significantly affected by the breed and by three management factors: "number of riders", "hours spent outside" and "group housing" (adjusted r2 = 15%, p<0.001). Thoroughbred and Warmblood horses displayed an increased adrenal response compared to Franches-Montagnes horses. Horses with several riders had a less pronounced reaction than horses with one rider, and horses that spent more time outside had a decreased response compared to horses that were stabled most of the time. Horses living in groups showed higher post-stimulatory cortisol values than horses that were housed singly. However, no significant associations of cortisol responsiveness with personality traits were found, and neither the use as elite or as amateur sport horses nor the discipline had an effect on the cortisol response. This suggests that optimizing husbandry conditions may be more important for improving equine welfare than changing their use.

Effects of size and personality on social learning and human-directed behaviour in horses (Equus caballus).

Due to our long history of living in close association with horses, these animals are suggested to have enhanced skills in understanding and communicating with humans. Today, horses have become important to humans for sport and leisure and their understanding of human behaviour and their human-directed behaviour are therefore of great importance. In this study, we investigated 22 horses in a human contact-seeking experiment where they were presented with an unsolvable problem and a detour experiment with a human demonstrator. The unsolvable problem consisted of pieces of carrot in a closed bucket and the detour resembled the shape of V. Additionally, personality traits of the participating horses were assessed. Interestingly, the full-sized horses (N = 11) showed more human-related behaviours when presented with an unsolvable problem compared to before the carrots were made unreachable (p = 0.033), while the ponies (N = 11) did not. However, neither the full-sized horses nor the ponies were significantly more successful in the detour after human demonstrations than in control trials. When comparing the two experiments, we found the task-oriented behaviour in the detour test to positively correlate with human proximity and eye contact-seeking behaviour towards humans during the unsolvable problem in the contact-seeking test. Interestingly, again this was only true for the full-sized horses (p < 0.05) and not for the ponies. From the horse personality questionnaire results, the traits excitability and anxiousness revealed strong negative correlations with human-directed behaviour in the contact-seeking experiment (p < 0.05). Hence, size (full-sized horse/pony) and personality influenced the human-related behaviours of the horses and we suggest a future focus on these aspects to deepen our understanding of human-horse communication.