Farmer, K., Krueger, K., & Byrne, R. (2010). Visual laterality in the domestic horse (Equus caballus) interacting with humans. Anim. Cogn., 13, 229–238.
Abstract: Most horses have a side on which they are easier to handle and a direction they favour when working on a circle, and recent studies have suggested a correlation between emotion and visual laterality when horses observe inanimate objects. As such lateralisation could provide important clues regarding the horse’s cognitive processes, we investigated whether horses also show laterality in association with people. We gave horses the choice of entering a chute to left or right, with and without the passive, non-interactive presence of a person unknown to them. The left eye was preferred for scanning under both conditions, but significantly more so when a person was present. Traditionally, riders handle horses only from the left, so we repeated the experiment with horses specifically trained on both sides. Again, there was a consistent preference for left eye scanning in the presence of a person, whether known to the horses or not. We also examined horses interacting with a person, using both traditionally and bilaterally trained horses. Both groups showed left eye preference for viewing the person, regardless of training and test procedure. For those horses tested under both passive and interactive conditions, the left eye was preferred significantly more during interaction. We suggest that most horses prefer to use their left eye for assessment and evaluation, and that there is an emotional aspect to the choice which may be positive or negative, depending on the circumstances. We believe these results have important practical implications and that emotional laterality should be taken into account in training methods.
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Flauger, B., Krueger, K., Gerhards, H., & Möstl, E. (2010). Simplified method to measure glucocorticoid metabolites in faeces of horses. Vet Res Comm, 34(2), 185–195.
Abstract: Glucocorticoids or their metabolites can be measured in several body fluids or excreta, including plasma, saliva, urine and faeces. In recent years the measurement of glucocorticoid metabolites (GCMs) in faeces has gained increasing attention, because of its suitability for wild populations. In horses, however, the group-specific enzyme immunoassay described so far has a limited racticability due to its complex extraction procedure. Therefore, we tested the applicability of
other enzyme immunoassays for glucocorticoid metabolites. The present study clearly proved that an enzyme immunoassay (EIA) for 11-oxoetiocholanolone using 11-oxoetiocholanolone-17-CMO: BSA (3α,11-oxo-A EIA) as antigen showed high amounts of immunoreactive substances. Therefore it was possible to use just a small amount of the supernatant of a methanolic suspension of faeces. The results
correlated well with the already described method for measuring GCMs in horse faeces, i.e. analysing the samples with an EIA after a two step clean up procedure of the samples (Merl et al. 2000). In addition, the 3α,11-oxo-A EIA has the advantage of providing a bigger difference between baseline values and peak values after ACTH stimulation. The new assay increased the accuracy of the test,
lowered the expenses per sample, and storing samples at room temperature after collection was less critical than with other assays investigated in our study. This is a big advantage both in the field of wildlife management of equids and in the field of equestrian sports and it shows the importance of choosing an assay which is in good accordance with the metabolites excreted in a given species.
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Krueger, K. (2010). “Erfasst” das Pferd die menschliche Psyche". In M. Dettling, C. Opgen-Rhein, & M. Kläschen (Eds.), Pferdegestützte Therapie bei psychischen Erkrankungen (pp. 40–51). Stuttgart: Schattauer Verlag.
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Krueger, K. (2010). Das Pferd im Blickpunkt der Wissenschaft. Wald: Xenophon Verlag.
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Krueger, K., & Krueger, K. (2010). Trainingslehre für Dressurpferde [Training the Dressage Horse]. Wald: Xenophon Verlag.
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Krueger, K., Flauger, B., Farmer, K., & Maros, K. (2011). Horses (Equus caballus) use human local enhancement cues and adjust to human attention. Anim. Cogn., 14(2), 187–201.
Abstract: This study evaluates the horse (Equus caballus) use of human local enhancement cues and reaction to human attention when making feeding decisions. The superior performance of dogs in observing human states of attention suggests this ability evolved with domestication. However, some species show an improved ability to read human cues through socialization and training. We observed 60 horses approach a bucket with feed in a three-way object-choice task when confronted with (a) an unfamiliar or (b) a familiar person in 4 different situations: (1) squatting behind the bucket, facing the horse (2) standing behind the bucket, facing the horse (3) standing behind the bucket in a back-turned position, gazing away from the horse and (4) standing a few meters from the bucket in a distant, back-turned position, again gazing away from the horse. Additionally, postures 1 and 2 were tested both with the person looking permanently at the horse and with the person alternating their gaze between the horse and the bucket. When the person remained behind the correct bucket, it was chosen significantly above chance. However, when the test person was turned and distant from the buckets, the horses’ performance deteriorated. In the turned person situations, the horses approached a familiar person and walked towards their focus of attention significantly more often than with an unfamiliar person. Additionally, in the squatting and standing person situations, some horses approached the person before approaching the correct bucket. This happened more with a familiar person. We therefore conclude that horses can use humans as a local enhancement cue independently of their body posture or gaze consistency when the persons remain close to the food source and that horses seem to orientate on the attention of familiar more than of unfamiliar persons. We suggest that socialization and training improve the ability of horses to read human cues.
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Krueger, K., & Flauger, B. (2011). Olfactory recognition of individual competitors by means of faeces in horse (Equus caballus). Anim. Cogn., 14(2), 245–257.
Abstract: Living in complex social systems requires perceptual and cognitive capacities for the recognition of group membership and individual competitors. Olfaction is one means by which this can be achieved. Many animals can identify individual proteins in urine, skin secretions, or saliva by scent. Additionally, marking behaviour in several mammals and especially in horses indicates the importance of sniffing conspecifics’ faeces for olfactory recognition. To test this hypothesis, we conducted two separate experiments: Experiment 1 addressed the question of whether horses can recognise the group membership of other horses by sniffing their faeces. The horses were presented with four faecal samples: (1) their own, (2) those of other members of their own group, (3) those of unfamiliar mares, and (4) those of unfamiliar geldings. Experiment two was designed to assess whether horses can identify the group member from whom a faecal sample came. Here, we presented two groups of horses with faecal samples from their group mates in random distribution. As controls, soil heaps and sheep faecal samples were used. In experiment one, horses distinguished their own from their conspecifics’ faeces, but did not differentiate between familiarity and sex. In experiment two, the horses from both groups paid most attention to the faeces of the horses from which they received the highest amount of aggressive behaviours. We therefore suggest that horses of both sexes can distinguish individual competitors among their group mates by the smell of their faeces.
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Krueger, K.. (2011). Soziales Lernen der Pferde. In Göttinger Pferdetage '11: Zucht, Haltung und Ernährung von Sportpferden (51). Warendorf: FN Verlag.
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Schneider, G., & Krueger, K. (2012). Third-party interventions keep social partners from exchanging affiliative interactions with others. Anim. Behav., 83(2), 377–387.
Abstract: Third-party interventions are defined as the interruption of dyadic interactions by third animals through direct physical contact, interposing or threats. Previous studies focused on the analysis of interventions against agonistic encounters. However, there have been no evaluations of interventions against affiliative behaviours, particularly in relation to the intervening animal�s social relationships and its social and spatial position. Horses, Equus caballus, are an interesting model species, as interventions against affiliative interactions occur more frequently than against agonistic interactions. In this study, 64 feral horses displayed 67 interventions in affiliative interactions and eight interventions in agonistic interactions within the observation period. We analysed the interventions in affiliative encounters, and found that it was mainly higher-ranking females that intervened in the affiliative interactions of group mates in the stable horse harems. The intervening animals took an active part in affiliative and agonistic encounters within the group, but did not occupy particular social roles or spatial positions. They intervened in affiliative interactions in which group mates with which they had social bonds interacted with other members of the group. They targeted the nonbonded animal and approached the one with which they were socially bonded. We suggest some species use third-party interventions in affiliative interactions to prevent competition for preferred social interaction partners from escalating into more costly agonistic encounters.
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Schneider, G., & Krueger, K. (2012). Third-party intervention. In Proceedings of the 2. International Equine Science Meeting (73). Wald: Xenophon Publishing.
Abstract: Third-party intervention is the interruption of a dyadic interaction by a third animal. We observed such interventions in affiliative interactions in free-ranging Esperia-ponies (Equus caballus). It is known that horses intervene in affiliative contexts especially when a preferred partner is involved, probably to protect their social bond to this preferred partner. To prove this hypothesis the present study investigated whether the preferred partner was targeted, i.e. challenged, or supported by the intervener or both randomly. Therefore we examined the social relationship between the intervener and both dyadic interacting individuals. We found that interveners usually supported individuals to which they have stronger social bonds than to other group mates, while they have no particular relationship to the targeted animals. This indicates that interveners in stable horse groups protect their social bonds to the supported animals by challenging their interaction partners. Of all observed horses only some mares showed intervention behaviour. Their social position, reflected by their position in the dominance hierarchy, social networks, and the spatial group structure were investigated. We found that interveners occupy no unique position, but they are involved in a high amount of affiliative interactions, high-ranking, and relatively aggressive. KW -
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