Investigating attentional processes in depressive-like domestic horses (Equus caballus)

A field approach to observing changes in behavioural welfare indicators over 2 years in stabled horses

In stabled horses, several behaviours are considered to be important indicators of the state of welfare at the individual level: stereotypies, aggressive behaviours towards humans and the "withdrawn", alert, sternal, lateral and observation postures. Until now, these behaviours have been extensively studied in relation to different horse management practices. However, little is known about their changes or consistency over time. This study aimed to investigate differences in the expression of these behaviours assessed on 44 stabled horses during an initial 3-month period and then again on the same individuals 2 years later. Out of the six behaviours studied, two showed significant differences between the 2 years with medium effect sizes: the levels of aggressiveness towards humans increased (Wilcoxon signed-rank test: V = 65, P = 0.005) and those of recumbent rest during the day decreased (V = 416, P < 0.001) over time. The results also suggested limited evidence of major changes over time in the expression of stereotypies, the "withdrawn", alert and observation postures. However, the principal component analyses carried out on all the behaviours showed that alert and observation postures may slightly decrease over time for some individuals. Regarding stereotypies and the "withdrawn" posture, the results mainly suggested a change at the individual level in the expression of these behaviours over time. This study provided new insights into the dynamic nature of several behaviours when the horses' living conditions are not fundamentally altered and raised hypotheses about the state of welfare of stabled individuals over a 2-year period.

Management of Donkeys in Assisted Interventions: A Snapshot

People working in the field of Animal-Assisted Interventions (AAIs) often state that they perceive animal welfare as a matter of paramount importance; nevertheless, most scientific literature focuses on the effectiveness of interventions from the user's perspective. Before focusing on the animals' management and welfare during their interactions with users, it is important to ensure animal welfare during their "ordinary lives". This article reports information and considerations about the management of donkeys involved in AAIs in Northern Italy. Six facilities with several years of experience in Donkey-Assisted Interventions were visited for the purpose of an initial data collection regarding the management of donkeys involved in AAIs. Some knowledge gaps regarding the nutritional needs of the donkey and its preventive medicine have been identified; this study also highlighted a need for efforts to create a more stimulating and enriched environment for animals involved in AAIs. Some possible areas for improvement in the management of donkeys involved in AAIs have been highlighted. Further studies are necessary to provide a more comprehensive picture of the welfare of donkeys involved in this context.

Transcriptomic signature related to poor welfare of sport horses

The improvement of horse welfare through housing conditions has become a real issue in recent years and have highlighted the detrimental effect of individual housing of horses on their health and behaviour. In this new study, we analysed the blood transcriptome of 45 sport horses housed individually that were previously examined for their behaviour and gut microbiota. We performed differential and regression analyses of gene expression, followed by downstream bioinformatic analyses, to unveil the molecular pathways related to the behavioural changes associated with welfare impairment in these sport horses. We found that aggressiveness towards humans was the behavioural indicator the most correlated to blood gene expression and that the pathways involved belonged mainly to systemic inflammation. In contrast, the correlations between genes, alert postures and unresponsiveness towards the environment were weak. When blood gene expression profiling was combined with faecal microbiota of a sub-population of horses, stereotypies came out as the most correlated to blood gene expression. This study shows that aggressiveness towards humans and stereotypies are behavioural indicators that covary with physiological alterations. Further studies are needed regarding the biological correlates of unresponsiveness to the environment and alert postures.

How to Understand Them? A Review of Emotional Indicators in Horses

Stabled horses often experience negative emotions due to the inappropriate living conditions imposed by humans. However, identifying what emotions horses experience and what can trigger positive and negative emotions in stabled horses can be challenging. In this article we present a brief history of the study of emotions and models that explain emotions from a scientific point of view and the physiological bases and functions of emotions. We then review and discuss physiological and behavioral indicators and cognitive bias tests developed to assess emotions in horses. Hormone concentrations, body temperature, the position of the ears, facial expressions and behaviors, such as approach and avoidance behaviors, can provide valuable information about emotional states in horses. The cognitive bias paradigm is a recent and robust tool to assess emotions in horses. Knowing how to evaluate the intensity and frequency of an individual's emotions can guide horse owners and caretakers to identify practices and activities that should be stimulated, avoided or even banned from the individual's life, in favor of a life worth living. The development and validation of novel indicators of emotions considering positive and negative contexts can help in these actions.

Understanding and treating equine behavioural problems

Behaviour-related issues are common in horses. Many 'undesirable behaviours' pose important safety concerns for the human handlers / riders / carers, as well as welfare concerns for the horse. Undesirable behaviours can also devalue a horse, or result in the horse being re-homed, relinquished, or euthanased. Undesirable behaviours occur for a range of reasons. These include physiological causes, poor management, and the use of inappropriate or poorly applied handling and training techniques. The potential contribution of each of these aspects must be considered when attempting to reduce or eliminate undesirable behaviours. Effectively modifying the existing behaviour includes investigation and treatment of potential physiological causes, assessing and adjusting existing handling, husbandry and management, and undertaking behaviour modifying training. Unlike in the treatment of dogs and cats, the use of psychotropic agents is uncommon in equine behaviour medicine but the benefits of using these agents in appropriate cases is gaining recognition. This review discusses potential causes for the development and maintenance of undesirable behaviours in horses and highlights the various considerations involved in determining the most appropriate course for reducing or eliminating these behaviours. There is also a brief discussion about the potential role of psychotropic agents as an additional component of an overall behaviour modification plan to reduce or eliminate undesirable behaviours in horses.

Horse welfare: A joint assessment of four categories of behavioural indicators using the AWIN protocol, scan sampling and surveys

Domesticated horses ( Equus caballus) can be exposed to a compromised welfare state and detecting a deterioration in welfare is essential to modify the animals' living conditions appropriately. This study focused on four categories of behavioural indicators, as markers of poor welfare: stereotypies, aggressiveness towards humans, unresponsiveness to the environment and hypervigilance. In the scientific literature, at least three assessment methods can be used to evaluate them: the Animal Welfare Indicators (AWIN) protocol, behavioural observations using scans and surveys. The question remains as to whether all these three methods allow an effective assessment of the four categories of behavioural indicators. To address this issue, the repeatability at a three-month interval and convergent validity of each measure (correlations between methods) were investigated on 202 horses housed in loose boxes. Overall, the repeatability and convergent validity were limited, highlighting the difficulty in assessing these indicators in horses. However, stereotypies and aggressiveness measures showed higher repeatability and convergent validity than those of unresponsiveness to the environment and hypervigilance. Behavioural observations using scans enabled the four categories of behavioural indicators to be detected more effectively. Suggestions of improvements are proposed for one-off measures such as those performed with the AWIN protocol. Regardless of the assessment method, very limited correlations were observed between the four categories of behavioural indicators, suggesting that they should all be included in a set of indicators used to assess the welfare state of horses, in conjunction with physiological and health measures.

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.

The Impact of Noise Anxiety on Behavior and Welfare of Horses from UK and US Owner’s Perspective

Noise anxiety is an over-reaction to loud noises commonly detected among pets and can greatly impact on their welfare and on their management. When exposed to noisy events, horses can show intense escape attempts, which may cause severe accidents for the horse and the rider/handler. The aim of the present study was to investigate, through a web survey, UK and US owners’ perception of noise anxiety severity in their horses, their management strategies and perceived efficacy. The questionnaire was shared via social networking and advertised as “What is your horse afraid of?”. Over a total of 1836 questionnaires filled out; 409 owners reported that their horse has shown unusual behavior during a noise event. A two-step cluster analysis identified two groups: very anxious (VA) and slightly anxious (SA). VA horses were reported to have higher frequency of anxiety behaviors; higher frequency of signs of noise reactivity; and their anxiety did not improve with time. The most used management strategies consisted in providing hay throughout the night, turning in/out their horse or moving it to a paddock. A binomial logistic regression identified that horses that have reported injuries during noise events were more likely to be clustered as VA (OR = 0.24, 95% CI: 0.08–0.76); while providing hay throughout the night was more likely to be very effective management strategy in SA horses (OR = 0.41, 95% CI: 0.16–1.01). Our results confirmed that noise anxiety is a growing behavioral problem that can lead to important welfare concerns for horses. New management strategies, including the use of medicinal products, should be considered to reduce behavioral and physiological signs and help horses to cope with noisy events.

Does the type of exercise affect tryptophan catabolism in horses?

Tryptophan (Trp) is an essential amino acid which metabolises via the kynurenine pathway to generate a number of bioactive substances referred to as kynurenines. Among those are 3-hydroxykynurenine (3-HKyn) and quinolinic acid, which are neurotoxic, as well as kynurenic acid (Kyna) and xanthurenic acid (XA), which, similarly to nicotinamide (NAm), show neuroprotective and anti-depressive effects. Routine exercise is known to modulate Trp metabolism in skeletal muscle and is thus believed to reduce the risk of depressive states in humans and laboratory animals. Analogously, it was hypothesised that exercise can influence Trp metabolism in horses as well. The aim of this study was to evaluate the influence of two different types of exercise on Trp metabolism in horses of the same breed. A total of 32 purebred Arabian horses were involved in the study. The 22 three-year-old racehorses were subjected to short-time intense exercise. Ten other horses were made to perform endurance competitions at a distance of 80 km. Blood samples were collected at rest and following the end of the exercise period. Plasma concentrations of Trp, kynurenine (Kyn), Kyna, 3-HKyn, XA and NAm were determined using Ultra-High Performance Liquid Chromatography-Electrospray Ionisation-Tandem Mass Spectrometry. Short-time intense exercise led to an increase in plasma concentrations of Kyn, Kyna and XA. The endurance effort induced an increase in Kyna and a decrease in Trp and NAm levels. Both types of exercise, short-time intensive exercise and endurance exercise induced an increase in Trp metabolites, especially Kyna, and did not induce an increase in Trp level. Thus, from a pathophysiological perspective of the kynurenine pathway's influence on mental state, both types of exercise induced beneficial effects in horses.

Experimental Tests for Measuring Individual Attentional Characteristics in Songbirds

Attention is defined as the ability to process selectively one aspect of the environment over others and is at the core of all cognitive processes such as learning, memorization, and categorization. Thus, evaluating and comparing attentional characteristics between individuals and according to situations is an important aspect of cognitive studies. Recent studies showed the interest of analyzing spontaneous attention in standardized situations, but data are still scarce, especially for songbirds. The present study adapted three tests of attention (towards visual non-social, visual social, and auditory stimuli) as tools for future comparative research in the European starling (Sturnus vulgaris), a species that is well known to present individual variations in social learning or engagement. Our results reveal that attentional characteristics (glances versus gazes) vary according to the stimulus broadcasted: more gazes towards unusual visual stimuli and species-specific auditory stimuli and more glances towards species-specific visual stimuli and hetero-specific auditory stimuli. This study revealing individual variations shows that these tests constitute a very useful and easy-to-use tool for evaluating spontaneous individual attentional characteristics and their modulation by a variety of factors. Our results also indicate that attentional skills are not a uniform concept and depend upon the modality and the stimulus type.

Exploratory Behaviours of Primitive Horses Based on Konik: A Preliminary Study

This study aimed at assessing the behaviour of Konik geldings and mares, kept in a stable and in a free-range system, during behavioural tests regarded as a determinant of the exploration urge. A total of 19 Konik horses kept in individual stables and in a free-range system were included in the study. The experiment was conducted in five phases separated by five-day breaks. A one-stage passive human test was performed during the first phase, a three-stage active human test-2nd phase, a three-stage unknown object test-3rd phase, a two-stage unknown surface test-4th phase, and a one-stage test of social isolation-5th phase. Ten attributes were analysed, including the horse sex and the keeping system. The results were also correlated with one another. Konik horses were found to show the urge to explore, although their behavioural responses are individual and stimulus dependent. In many cases, the horse sex and the keeping system influence the exploratory behaviour, although it is manifested by a greater intensity in geldings than in mares, and in free-range horses than in those kept in a stable. The study is regarded as preliminary due to the small number of horses in the study groups.

On-Farm Welfare Assessment of Horses: The Risks of Putting the Cart before the Horse

Although the question of animal welfare has been an important source of concern in the scientific community for several decades, many aspects are still under debate. On-farm assessments have to be rapid, acceptable to farmers and safe for both the assessors and animals. They are thus very demanding, with multiple decisions to make, such as the choice of appropriate indicators, sampling methods and scoring. Research has moved from resource-based to animal-based criteria, which reflects the subjective welfare state of an animal rather than relying upon external indices. In the present review, we describe two major (i.e., the most frequently/recently tested or disseminated) protocols: one in low-/middle-income countries, and the other in high-income countries, for on-farm assessments of horses, using animal-based resources; we evaluate their strengths and limitations, and then we compare their results with those obtained by various other studies. We propose lines of improvement, particularly in view of public dissemination, and offer suggestions for further refinement or new protocols. We emphasize the high risks of putting the cart before the horse, i.e., proposing protocols that rely upon indicators and sampling methods that need to be refined, as this could lead to under-evaluation (or less likely over-evaluation) of current welfare problems. Because welfare is a subjective experience, the true representation of an individual's actual welfare status has to be evaluated by using objective assessment tools (that are validated and have a scientific basis) used by well-trained observers.

Non-invasive stress evaluation in domestic horses (Equus caballus): impact of housing conditions on sensory laterality and immunoglobulin A

The study aimed to evaluate sensory laterality and concentration of faecal immunoglobulin A (IgA) as non-invasive measures of stress in horses by comparing them with the already established measures of motor laterality and faecal glucocorticoid metabolites (FGMs). Eleven three-year-old horses were exposed to known stressful situations (change of housing, initial training) to assess the two new parameters. Sensory laterality initially shifted significantly to the left and faecal FGMs were significantly increased on the change from group to individual housing and remained high through initial training. Motor laterality shifted significantly to the left after one week of individual stabling. Faecal IgA remained unchanged throughout the experiment. We therefore suggest that sensory laterality may be helpful in assessing acute stress in horses, especially on an individual level, as it proved to be an objective behavioural parameter that is easy to observe. Comparably, motor laterality may be helpful in assessing long-lasting stress. The results indicate that stress changes sensory laterality in horses, but further research is needed on a larger sample to evaluate elevated chronic stress, as it was not clear whether the horses of the present study experienced compromised welfare, which it has been proposed may affect faecal IgA.

Mutual interactions between cognition and welfare: The horse as an animal model

Research in cognitive psychology has repeatedly shown how much cognition and emotions are mutually related to one another. Psychological disorders are associated with cognitive (attention, memory and judgment) biases and chronic pain may affect attention, learning or memory. Laboratory studies have provided useful insights about the processes involved but observations about spontaneous animal models, living in different stress/welfare conditions may help understand further how cognition and welfare are interrelated in the « real world ». Domestic horses constitute such a model as they live in a variety of conditions that impact differently their welfare state. In the present review, we try and provide an overview of the scientific literature on cognition and welfare of domestic horses and their interrelationship. We address how emotions and welfare may affect cognitive processes in horses and impact the way they perceive their environment (including work). We propose new methods for assessing the relationship between welfare and cognition and open up the discussion on the evolution of the brain and the part domestication may have played.

Housing Horses in Individual Boxes Is a Challenge with Regard to Welfare

Horses are mainly housed in individual boxes. This housing system is reported to be highly detrimental with regard to welfare and could trigger the expression of four behavioural indicators of a compromised welfare state: stereotypies, aggressiveness toward humans, unresponsiveness to the environment, and stress-related behaviours. The aim of this study was to identify housing and management factors that could alleviate the detrimental effects of individual boxes on welfare. A total of 187 horses were observed over 50 days by scan sampling. The impact of 12 factors was investigated on the expression of the four behavioural indicators in three different analyses. The results show that the majority of factors tested did not influence the expression of the behavioural indicators. Only three (straw bedding, a window opening onto the external environment, and a reduced quantity of concentrated feed) would have beneficial, although limited, effects. Furthermore, the longer the horses spent in individual boxes, the more likely they were to express unresponsiveness to the environment. To preserve the welfare of horses, it seems necessary to allow free exercise, interactions with conspecifics, and fibre consumption as often as possible, to ensure the satisfaction of the species' behavioural and physiological needs.

Could posture reflect welfare state? A study using geometric morphometrics in riding school horses

Despite the fact that animal posture is known to reflect emotional state, the presence of chronic postures associated with poor welfare has not been investigated with an objective tool for measuring, quantifying and comparing postures. The use of morphometric geometrics (GM) to describe horse posture (profile of the dorsum) has shown to be an effective method of distinguishing populations that are known to differ in terms of welfare states. Here we investigated photographs of 85 riding school horses differing in terms of welfare state, in order to determine if a specific posture (modelled by GM) is associated with altered welfare. The welfare state was estimated with the prevalence of stereotypic or abnormal repetitive behaviours, depressed-like posture and the ear positions. ANOVA results show that horses with stereotypic or abnormal behaviour, and to a lesser degree horses with depressed-like postures, tend to have a flatter, or even hollow, dorsal profile, especially at the neck and croup levels. These altered profiles could represent an additional indicator of poor welfare, easy to use in the field or by owners.

What is animal happiness?

Today, we see a growing concern for the quality of life of nonhuman animals and an accompanying call for viable means of assessing how well animals thrive. Past research focused on minimizing negatives such as stress, while more recent endeavors strive to promote positives such as happiness. But what is animal happiness? Although often mentioned, the term lacks a clear definition. With recent advances in the study of animal emotion, current interest into positive rather than negative experiences, and the call for captive and domesticated animals to have good lives, the time is ripe to examine the concept of animal happiness. We draw from the human and animal literature to delineate a concept of animal happiness and propose how to assess it. We argue that animal happiness depends on how an individual feels generally-that is, a typical level of affect.

Attentional state and brain processes: state-dependent lateralization of EEG profiles in horses

Lateralization of brain functions has been suggested to provide individuals with advantages, such as an increase of neural efficiency. The right hemisphere is likely to be specialized for processing attention for details and the left hemisphere for categorization of stimuli. Thus attentional processes actually may underlie lateralization. In the present study, we hypothesized that the attentional state of horses could be reflected in the lateralization of brain responses. We used i) a recently developed attention test to measure horses’ visual attentional responses towards a standardized stimulus and ii) a recently developed portable EEG telemetric tool to measure brain responses. A particular emphasis was given to the types of waves (EEG power profile) and their side of production when horses were either attentive towards a visual stimulus or quiet standing. The results confirmed that a higher attentional state is associated with a higher proportion of gamma waves. There was moreover an interaction between the attentional state, the hemisphere and the EEG profile: attention towards the visual stimulus was associated with a significant increase of gamma wave proportion in the right hemisphere while “inattention” was associated with more alpha and beta waves in the left hemisphere. These first results are highly promising and contribute to the large debate on functional lateralization.

Low plasma cortisol and fecal cortisol metabolite measures as indicators of compromised welfare in domestic horses (Equus caballus)

The hypothalamic-pituitary-adrenal (HPA) axis response to chronic stress is far from straight forward, particularly with regards to animal welfare. There are reports of no effect as well as both decreases and increases in cortisol after chronic stressors. Therefore, the first aim of the present study was to determine how measures of compromised welfare, such as chronic pain and haematological anomalies, related to cortisol levels in domestic horses (Equus caballus). Domestic horses are an informative model to investigate the impact of chronic stress (due to environment, pain, work, housing conditions…) on the HPA axis. The second aim was to determine whether levels of fecal cortisol metabolites (FCM) may be used as an indicator of welfare measures. The present study used fifty-nine horses (44 geldings and 15 mares), from three riding centres in Brittany, France. The primary findings show that horses whose welfare was clearly compromised (as indicated by an unusual ears backward position, presence of vertebral problems or haematological anomalies, e.g. anaemia) also had lower levels of both FCM and plasma cortisol. This work extends our previous findings showing that withdrawn postures, indicators of depressive-like behavior in horses, are associated with lower plasma cortisol levels. We also found that evening plasma cortisol levels positively correlated with FCM levels in horses. Future research aims to determine the extent to which factors of influence on welfare, such as living conditions (e.g. single stalls versus group housing in pasture or paddocks), early life factors, and human interaction, act as mediators of cortisol levels in horses.

A novel test for evaluating horses' spontaneous visual attention is predictive of attention in operant learning tasks

Attention is described as the ability to process selectively one aspect of the environment over others. In this study, we characterized horses' spontaneous attention by designing a novel visual attention test (VAT) that is easy to apply in the animal's home environment. The test was repeated over three consecutive days and repeated again 6 months later in order to assess inter-individual variations and intra-individual stability. Different patterns of attention have been revealed: 'overall' attention when the horse merely gazed at the stimulus and 'fixed' attention characterized by fixity and orientation of at least the visual and auditory organs towards the stimulus. The individual attention characteristics remained consistent over time (after 6 months, Spearman correlation test, P < 0.05). The validity of this novel test as a predictor of individual attentional skills was assessed by comparing the results, for the same horses, with those obtained in both a 'classical' experimental attention test the 'five-choice serial reaction time task' (5-CSRTT) and a work situation (lunge working context). Our results revealed that (i) individual variations remained consistent across tests and (ii) the VAT attention measures were not only predictive of attentional skills but also of learning abilities. Differences appeared however between the first day of testing and the following test days: attention structure on the second day was predictive of learning abilities, attention performances in the 5-CSRRT and at work. The VAT appears as a promising easy-to-use tool to assess animals' attention characteristics and the impact of different factors of variation on attention.

An Ambulatory Electroencephalography System for Freely Moving Horses: An Innovating Approach

Electroencephalography (EEG) that has been extensively studied in humans presents also a large interest for studies on animal brain processes. However, since the quality of the recordings is altered by muscular activity, most EEG recordings on animals are obtained using invasive methods with deeply implanted electrodes. This requires anesthesia and can thus only be used in laboratory or clinical settings. As EEG is a very useful tool both for detecting brain alterations due to diseases or accidents and to evaluate the arousal and attentional state of the animal, it seemed crucial to develop a tool that would make such recordings possible in the horse’s home environment, with a freely moving horse. Such a tool should neither be invasive nor cause discomforts to the horse as the usual other practice which consists, after shaving the zone, in gluing the electrodes to the skin. To fulfill these requirements, we developed a novel EEG headset adapted to the horse’s head that allows an easy and fast positioning of the electrodes and that can be used in the home environment on a freely moving horse. In this study, we show that this EEG headset allows to obtain reliable recordings, and we propose an original evaluation of an animal’s “EEG profile” that allows comparisons between individuals and situations. This EEG headset opens new possibilities of investigation on horse cognition, and it can also become a useful tool for veterinarians to evaluate cerebral disorders or check the anesthesia level during a surgery.