Abstract: Growing evidence shows a variety of sensorial and motor asymmetries in social and non-social interactions in various species, indicating a lateralized processing of information by the brain. Using digital video cameras on tripods and drones, this study investigated lateralization in frequency and duration of social behavior patterns, in affiliative, agonistic, and resting contexts, in a feral population of horses (Equus ferus caballus) in Northern Portugal, consisting of 37 individuals organized in eight harem groups. Affiliative interactions (including grooming) were more often performed, and lasted longer, when recipients were positioned to the right side. In recumbent resting (animals lying down) episodes on the left side lasted longer. Our results of an affiliative behavior having a right side tendency, provide partial support to the valence-specific hypothesis of Ahern and Schwartz (1979) – left hemisphere dominance for positive affect, affiliative behaviors. Longer recumbent resting episodes on the left side may be due to synchronization. However, in both instances it is discussed how lateralization may be context dependent. Investigating the position asymmetries of social behaviors in feral equids will contribute to a better understanding of differential lateralization and hemispheric specialization from the ecological and evolutionary perspectives.

Abstract: Group housed horses at a stud farm/riding stable in Belgium were observed on 17 days between 21 February and 25 April 2008, totalling 54hr25min of detailed data. The original group consisted of 8 Irish Cob mares, 1 Warmblood mare, 1 Arabian gelding and 2 Arabian mares. The group had been established in December 2007. During the course of the study 5 horses were removed from the group and 2 foals were born. 3 highly pregnant mares were housed adjacent to the group for part of the period. Horses were regularly used for lessons. Available surface area differed with the group on pasture at the end. Continuous all occurrence sampling of 10 agonistic and 2 affiliative behaviours was carried out for all group members present. Overall the group showed a frequency of 44.75 agonistic interactions per hour and 11.25 affiliative per hour. Of those agonistic interactions 46.3% were threats while 47% were less active interactions (displacement, being avoided), leaving only 6.7% more aggressive interactions ( mainly biting, some kicking and chasing). The effect on acting agonistically was not significant for age (p=0.1591) and borderline significant for density (p=0.0627). The analysis of the frequency of affiliative interactions showed there is no significant effect of age (p=0.1865) or density (p=0.7923). Agonistic and affiliative interactions were not significantly correlated (p=0.72). Affiliative behaviour a horse received showed a borderline effect (p=0.0787) on agonistic behaviour, as did the interaction between received agonistic and affiliative interactions (p=0.0725). Received agonistic interactions had a borderline negative effect (p=0.0656) on affiliative behaviour. A dominance hierarchy was calculated based on agonistic interactions using Empirical Bayes’ estimates based on Poisson regression with random effects. Agonistic behaviour expressed to other horses was significantly effected by relative rank (p=0.0243). Overall horses tended to be 3.7 times more aggressive towards lower ranking horses compared to higher ranking horses. Affiliative behaviour shown to other horses was not significantly influenced by the rank of the social partner (p=0.7915). Some individuals did show a significant effect whereby they showed more affiliative behaviour towards lower ranking individuals. This study was a small project to look at a practical situation of riding horses being kept in group housing. The frequent changes in group composition and available surface made it possible to look at agonistic and affiliative interactions in such circumstances. This is useful as instability in group composition is often used as main reason not to keep horses in social groups. The results from this study showed a borderline effect of density on agonistic behaviour. In reality it was also influenced by practical details, like a narrow paddock with only 2 hay crates on the smallest surface. Rank in a dominance hierarchy, based on agonistic behaviour, had a significant effect on the agonistic behaviour expressed towards higher or lower ranking horses. No injuries or escalating fights were observed. This study shows it is possible to keep a group of riding horses in a social context without excessive aggression.

Abstract: Recent research has shown that domestic dogs are particularly good at reading human attentional cues, often outperforming chimpanzees and hand reared wolves [1, 2]. It has been suggested that the close evolutionary relationship between humans and dogs has led to the development of this ability, however very few other species have been studied [3]. We tested the ability of 24 domestic horses to discriminate between an attentive and inattentive person when choosing whom to approach for food. While the attentive person faced forwards, the inattentive person either stood with their body turned 180° away from the subject (body orientation condition), stood with their body facing forwards but their head facing away (head orientation condition) or stood facing forwards but with their eyes closed (eyes closed condition). A fourth, mixed condition was included where the attentive person stood with their body facing away from the subjects but their head turned towards the subject while the inattentive person stood with their body facing the subject but their head turned away. Horses chose the attentive person significantly more often using the body cue (n = 24, k = 19, p = 0.003), the head cue (n = 24, k = 18, p = 0.011), and the eye cue (n = 24, k = 19, p = 0.003) but not the mixed cue (n = 24, k = 13, p = 0.42). In an additional pilot study, horses were tested in an object choice task. A human experimenter cued one of two buckets by either tapping the bucket (tap condition), orienting their body towards the bucket and pointing (body and point condition), pointing while facing forwards (point condition) or orienting their body towards the bucket (body condition). If the subjects chose the correct bucket they were rewarded. Subjects were able to use the tap cue (n = 31, k = 21, p = 0.035), body + point cue (n= 31, k = 21, p = 0.035) and the point cue (n = 30, k = 21, p = 0.021) but not the body cue (n = 31, k = 11, p = 0.076). These results taken together suggest that domestic horses are also very sensitive to human attentional cues, including gaze.
Keywords:
social cognition, animal-human interaction, horses, attention attribution, domestication
1. Hare, B., Brown, M., Williamson, C., and Tomasello, M. (2002). The domestication of social cognition in dogs. Science 298, 1634-1636.
2. Gacsi, M., Miklosi, A., Varga, O., Topal, J., and Csanyi, V. (2004). Are readers of our face readers of our minds` Dogs (Canis familiaris) show situation-dependent recognition of human’s attention. Animal Cognition 7, 144-153.
3. Hare, B., and Tomasello, M. (2005). Human-like social skills in dogs? Trends Cogn. Sci. 9, 439-444.

Abstract: According to Interpersonal Theory every interaction is motivated by efforts to achieve and maintain self-esteem and to avoid anxiety. People"s characteristic ways of accomplishing these ends are called interpersonal reflexes. Those interpersonal reflexes are evident in interaction with animals, since they are determined by the interpersonal traits of personality. We wanted to catch the typical interpersonal reflexes in between humans and horses compared to pet animals.
We used the self rating assessment instrument “Inventory of Problematic Interactions with Animals” (IPI – Animals), which bases on a Interpersonal Circumplex Model (Human Animal Circumplex; HAC) and was constructed to catch specific dispositions of distress caused by animals using two dimensions (too dominant vrs too submissive and too warm versus too cold). Data of 233 male adolescents (93 of them actual pet owners, from that 12 horse owners) were collected.
We found that different pet preferences holds distinct locations in the HAC. Horse persons differ from dog and cat persons within the dimension dominance (dog: chi2(df126) =161.54 p= .018; cat: chi2(df126) =199.95 p= .045). Persons, who own a horse or would wish to own one, describe themselves as dominant, but warm interactors. They report that they want horses to notice them. They tend do too much for them and behave very effusively with them. On the other hand they feel that the animal takes too much advantage of the relationship.

Abstract: In order to improve the housing conditions of stallions in individual boxes by offering a possibility to have more social contact, the Swiss national stud farm tested a new box system for horses, allowing increased physical contact with the neighbouring stallion. The aim of this part of the study was to investigate whether this type of housing system (named “social box”) potentially induces a change in stress reactions in stallions compared to conventional boxes. Therefore faecal cortisol metabolite (FCM) concentration was measured as a non-invasive parameter to assess endocrine responses related to this new environment.
Four groups each consisting of eight adult Freiberger breeding stallions were included in the test design. Every stallion spent three weeks in a conventional box and in a social box respectively (cross-over design). The conventional box consisted of a separation wall with a lower opaque part and an upper part with vertical barriers (5 cm between barriers), allowing visual and olfactory contact but strongly limiting tactile contact. The separating wall of the social box consisted of two lateral sections, one part being opaque to the ceiling and the second part consisting of vertical barriers (30 cm between barriers), allowing the horse to have physical contact with its neighbour or to avoid it.
In horses, FCM concentration reflects an average level of circulating cortisol over a period of approximatively 24h. Faecal samples were collected the day following integration in social / conventional boxes, reflecting the potential stress induced by increased social interactions during the integration. In order to asses potential chronical stress, faeces samples were also collected in week one, two and three after the integration into the social / conventional box (in total: 4 samples per horse and housing system). The samples were immediately stored at -20°C until they were analysed. The samples were not analysed in the laboratory until the end of the experiment, therefore the duration of conservation in the freezer varied from 40 to 429 days.
A considerable percentage of data from groups 1 and 2 was below the detection limit (<0.8 ng/g) (Tab. 1). Thus the statistical analysis was conducted with the FCM concentration from groups 3 and 4 (n horses = 16) which contained no values below the detection limit.
Tab. 1: Details about FCM values and storage time for the 4 groups of stallions
Group Storage duration [d] Proportion of data below the detection limit (<0.8 ng/g) Mean [ng/g] Median [ng/g]
Group 1 384-429 55.6 % 2.2 0
Group 2 315-360 25.5 % 5.8 6.3
Group 3 41-79 0.0 % 8.7 8.0
Group 4 40-85 0.0 % 5.8 5.4
Despite the impressive social interactions observed between the stallions directly after being introduced into the social boxes, we did not find any differences in FCM concentration between the stallions being introduced into the conventional box and the social box on the day of integration (social box: n samples = 16, mean±SD: 6.9±4.7 ng/g; conventional box: n samples = 16, mean±SD: 9.0±11.2 ng/g; Wilcoxon signed rank test V = 70, p = 0.94).
Overall the samples taken during integration and in week one, two and three did not show evidence of changes in FCM concentration in either housing system over a longer period of time (social box: n samples = 64, mean±SD: 7.9±6.2 ng/g; conventional box: n samples = 64, mean±SD: 6.6±3.4 ng/g; Linear mixed model (LMM), p = 0.56).
Our results suggest that the possibility of having physical contact with a conspecific does not induce changes in FCM concentration in breeding stallions. The considerable percentage of values below the detection limit in groups 1 and 2 seemed to correlate with the increasing duration of storage before analysis. During the IESM Network Meeting 2015, we would like to discuss possible methodological issues and the possibilities to correctly integrate these low values in the statistical analysis.