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Marr, I., Stefanski, V., & Krueger, K. (2022). Lateralität – ein Indikator für das Tierwohl?[Laterality – an animal welfare indicator?]. Der Praktische Tierarzt, 103(12/2022), 1246–12757.
Abstract: Ein gutes Tierwohl definiert sich nicht nur durch die Abwesenheit von Stressindikatoren, sondern auch durch das Vorhandensein von Indikatoren, die auf ein gutes Wohlergehen hinweisen. So können stressbedingte Erkrankungen vermieden werden. Zur Bestimmung des Tierwohls bei Pferden wurde daher untersucht, inwieweit sich die sensorische Lateralität (einseitiger Gebrauch von Sinnesorganen) und die motorische Lateralität (einseitiger Gebrauch von Gliedmaßen) als einfach, schnell und kostengünstig zu erhebende Parameter eignen. Hierzu werden neben aktueller Literatur auch die eigenen Untersuchungsergebnisse zusammenfassend dargestellt. Die nach außen sichtbar werdende sensorische und motorische Lateralität sind das Resultat der cerebralen Lateralisierung. Dies beinhaltet nicht nur die Aufgabenteilung beider Gehirnhälften für ein effizienteres Aufnehmen und Speichern von Informationen, sondern sie steht auch in Verbindung mit der Entstehung und Verarbeitung von Emotionen, die maßgeblich am Wohlergehen eines Lebewesens beteiligt sind. Kurzzeitige Stressoren führen zu einer Erregung, die je nach Erfahrungen mit positiven oder negativen Emotionen in Verbindung steht. Emotionen helfen dem Organismus dabei, zu überleben. Andauernde negative Emotionen durch regelmäßige oder anhaltende negative Ereignisse führen zu Stress und reduzieren die Erwartung positiver Ereignisse (negativer cognitive Bias). Das Tier ist im Wohlergehen beeinträchtigt. Jüngst zeigte insbesondere die Messung der motorischen Lateralität Potenzial als Indikator für lang anhaltenden und chronischen Stress, denn gestresste Pferde, deren Stresshormonlevel stark ansteigt, zeigen einen zunehmenden Gebrauch der linken Gliedmaßen über einen längeren Zeitraum. Weiterhin zeigen erste Messungen einen Zusammenhang zwischen einer linksseitigen motorischen Lateralität und einer reduzierten Erwartung positiver Ereignisse (negativer cognitive Bias). Zusammen mit der sensorischen Lateralität, die in einer akuten Stressphase ebenso eine Linksverschiebung zeigt und somit als Indikator für Kurzzeitstress gilt, kann eine generelle, vermehrte Linksseitigkeit auch einen Hinweis auf erhöhte Emotionalität und Stressanfälligkeit sein. Eine sich steigernde Linksseitigkeit bedeutet eine präferierte Informationsverarbeitung durch die rechte Gehirnhälfte, die beispielsweise reaktives Verhalten, starke Emotionen und Stressantworten steuert. Es stellte sich jedoch heraus, dass wie bei allen Stressindikatoren auch in der Lateralitätsmessung ein Vergleichswert aus einer vorangegangenen Messung notwendig ist, denn nur Veränderungen zum häufiger werdenden Gebrauch der linken Seite können auf Stress bei Pferden hindeuten und die parallele Erhebung weiterer Parameter, wie zum Beispiel das Verhalten oder Stresshormone, können die Aussage der Lateralität bekräftigen.
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Benz, B., Münzing, C., Krueger, K., & Winter, D. (2014). Ethologische Untersuchung von Heuraufen in der Pferdehaltung [Ethological investigation of hayracks in equine husbandry]. Landtechnik, 69(5), 239–244.
Abstract: Eine tiergerechte, physiologisch und anatomisch auf die Bedürfnisse der Pferde ausgerichtete
Raufutterversorgung sollte die Kaubedürfnisse und die Beschäftigungszeiten von Pferden ausreichend berücksichtigen. Daher – und auch aufgrund des bestehenden Kostendrucks bei Raufutter – steigt das Interesse an Raufutterraufen, durch die möglicherweise die Futteraufnahmezeiten verlängert sowie Futterverluste minimiert werden können. Die vorliegende Untersuchung vergleicht das Fressverhalten und die Körperhaltung von acht Pferden beim Einsatz von drei unterschiedlichen Futterraufen mit der Bodenfütterung in Einzelboxenhaltung. Die Ergebnisse dieser Studie lassen den Schluss zu, dass der Einsatz von Raufutterraufen die Futteraufnahmezeiten verlängert und somit längere Beschäftigungszeiten für die Futteraufnahme gewährleistet werden. Außerdem konnte festgestellt werden, dass die Pferde das Raufutter bei einer der drei untersuchten Raufen überwiegend mit natürlicher Kopf- Hals-Haltung aufnahmen. [Regarding the species horse, an appropriate supply of roughage should take into account the need to chew as well as the need for occupation. In this context, and due to the current cost pressure for hay, the interest in roughage racks increases. It is assumed that roughage racks could help to extend the feeding time and reduce food losses. The present study places the emphasis on the observation of the feeding behaviour of eight horses in single horse boxes. Three different roughage racks are compared to traditional feeding on the floor. On the basis of the results it may be concluded that the use of roughage racks extends the feeding time and thus ensures longer occupation. In one of the three roughage racks investigated the horses mainly eat in a natural posture of their head and neck.] |
Krueger, K., Esch, L., Farmer, K., & Marr, I. (2021). Basic Needs in Horses?--A Literature Review. Animals, 11(6), 1798.
Abstract: Every animal species has particular environmental requirements that are essential for its welfare, and when these so-called “basic needs” are not fulfilled, the animals suffer. The basic needs of horses have been claimed to be social contact, social companionship, free movement and access to roughage. To assess whether horses suffer when one or more of the four proposed basic needs are restricted, we examined several studies (n = 38) that reported behavioural and physiological reactions to these restrictions. We assigned the studies according to the four types of responses investigated: (a) Stress, (b) Active, (c) Passive, and (d) Abnormal Behaviour. Furthermore, the number of studies indicating that horses reacted to the restrictions were compared with the number of studies reporting no reaction. The limited number of studies available on single management restrictions did not allow conclusions to be drawn on the effect of each restriction separately, especially in the case of social companionship. However, when combinations of social contact, free movement and access to roughage were restricted, many of the horses had developed responses consistent with suffering. Passive Responses, indicating acute suffering, and Abnormal Behaviour, indicating suffering currently or at some time in the past, were especially clearly demonstrated. This provides further evidence of the usefulness of assessing behavioural parameters in combination with physiological measurements when evaluating horse welfare. This meta-analysis of the literature confirms that it is justified to claim that social contact, free movement and access to roughage are basic needs in horses.
Keywords: abnormal behaviour; active responses; horse; movement; passive responses; roughage; stress; social contact
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Krueger, K., Schwarz, S., Marr, I., & Farmer, K. (2022). Laterality in Horse Training: Psychological and Physical Balance and Coordination and Strength Rather Than Straightness. Animals, 12(8), 1042.
Abstract: For centuries, a goal of training in many equestrian disciplines has been to straighten the horse, which is considered a key element in achieving its responsiveness and suppleness. However, laterality is a naturally occurring phenomenon in horses and encompasses body asymmetry, motor laterality and sensory laterality. Furthermore, forcibly counterbalancing motor laterality has been considered a cause of psychological imbalance in humans. Perhaps asymmetry and laterality should rather be accepted, with a focus on training psychological and physical balance, coordination and equal strength on both sides instead of enforcing “straightness”. To explore this, we conducted a review of the literature on the function and causes of motor and sensory laterality in horses, especially in horses when trained on the ground or under a rider. The literature reveals that body asymmetry is innate but does not prevent the horse from performing at a high level under a rider. Motor laterality is equally distributed in feral horses, while in domestic horses, age, breed, training and carrying a rider may cause left leg preferences. Most horses initially observe novel persons and potentially threatening objects or situations with their left sensory organs. Pronounced preferences for the use of left sensory organs or limbs indicate that the horse is experiencing increased emotionality or stress, and long-term insufficiencies in welfare, housing or training may result in left shifts in motor and sensory laterality and pessimistic mentalities. Therefore, increasing laterality can be regarded as an indicator for insufficiencies in housing, handling and training. We propose that laterality be recognized as a welfare indicator and that straightening the horse should be achieved by conducting training focused on balance, coordination and equal strength on both sides.
Keywords: balance; body asymmetry; equitation; horse; motor laterality; sensory laterality; stress; welfare
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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. Keywords: ACTH challenge; enzyme immunoassay; stress behaviour; cortisol
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Krueger, K. (2008). Social Ecology of Horses. In j. Korb and J. Heinze (Ed.), Ecology of Social Evolution (pp. 195–206). Heidelberg: Springer Verlag.
Abstract: Horses (Equidae ) are believed to clearly demonstrate the links between ecology and social organization. Their social cognitive abilities enable them to succeed in many different environments, including those provided for them by humans, or the ones domestic horses encounter when escaping from their human care takers. Living in groups takes different shapes in equids. Their aggregation and group cohesion can be explained by Hamilton“s selfish herd theory. However, when an individual joins and to which group it joins appears to be an active individual decision depending on predation pressure, intra group harassment and resource availability. The latest research concerning the social knowledge horses display in eavesdropping experiments affirms the need for an extension of simple herd concepts in horses for a cognitive component. Horses obviously realize the social composition of their group and determine their own position in it. The horses exceedingly flexible social behavior demands for explanations about the cognitive mechanisms, which allow them to make individual decisions. ”Ecology conditions like those that favour the evolution of open behavioural programs sometimes also favour the evolution of the beginnings of consciousness, by favouring conscious choice. Or in other words, consciousness originates with the choice that are left open by open behavioural programs." Popper (1977)
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Krueger, K., & Farmer, K. (2011). Laterality in the Horse [Lateralität beim Pferd ]. mup, 4, 160–167.
Abstract: Horses are one-sided, not only on a motor level, but they also prefer to use one eye, ear or nostril over the other under particular circumstances. Horses usually prefer using the left eye to observe novel objects and humans. This preference is more marked in emotional situations and when confronted with unknown persons. Thus the horse’s visual laterality provides a good option for assessing its mental state during training or in human-horse interactions. A strong preference for the left eye may signal that a horse cannot deal with certain training situations or is emotionally affected by a particular person.
Pferde benutzen für die Begutachtung von Objekten und Menschen bevorzugt eine bestimmte Nüster, ein Ohr oder ein Auge. So betrachten die meisten Pferde Objekte und Menschen mit dem linken Auge. Die Lateralitätsforschung erklärt diese sensorische Lateralität mit der Verarbeitung von Informationen unterschiedlicher Qualität in verschiedenen Gehirnhälften und zeigt auf, dass positive und negative emotionale Informationen sowie soziale Sachverhalte mit dem linken Auge aufgenommen und vorwiegend an die rechte Gehirnhälfte weitergegeben werden. In diesem Zusammenhang ermöglicht die visuelle Lateralität, den Gemütszustand des Pferdes im Training und im therapeutischen Fördereinsatz zu erkennen und zu berücksichtigen. |
Krueger, K. (2007). Behaviour of horses in the “round pen technique”. Appl. Anim. Behav. Sci., 104(1-2), 162–170.
Abstract: I investigated the behavioural background of the way horses learn to follow humans in the “round pen technique” suggested by “horse whisperers” as a gentle method for initial horse training. Though the practicability of this technique has been adequately demonstrated in the past, the horses' behaviour during such training has not yet been documented in detail. In a riding arena, horses, that did not follow the trainer immediately, were chased away so that they galloped around the trainer. Galloping horses showed specific behaviour such as turning the ear to the trainer, chewing, licking, and stretching head and throat downwards. In subsequent trials horses needed to be chased for less time and finally followed immediately, even when conditions were changed or the trainer was replaced by another person. This suggests that horses learn to follow in this particular situation and also show some generalisation. However, following did not occur on a pasture even after several successful trials in the riding arena.
Keywords: Learning; Dominance relationship; Horse; Human-animal relationships
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Schanz, L., Krueger, K., & Hintze, S. (2019). Sex and Age Don't Matter, but Breed Type Does--Factors Influencing Eye Wrinkle Expression in Horses. Front. Vet. Sci., 6, 154.
Abstract: Identifying valid indicators to assess animals' emotional states is a critical objective of animal welfare science. In horses, eye wrinkles above the eyeball have been shown to be affected by pain and other emotional states. From other species we know that individual characteristics, e.g. age in humans, affect facial wrinkles, but it has not yet been investigated whether eye wrinkle expression in horses is systematically affected by such characteristics. Therefore, the aim of this study was to assess how age, sex, breed type, body condition and coat colour affect the expression and/or the assessment of eye wrinkles in horses. To this end, we adapted the eye wrinkle assessment scale from Hintze et al. (2016) and assessed eye wrinkle expression in pictures taken from the left and the right eye of 181 horses in a presumably neutral situation, using five outcome measures: a qualitative first impression reflecting how worried the horse is perceived by humans, the extent to which the brow is raised, the number of wrinkles, their markedness and the angle between a line through both corners of the eye and the topmost wrinkle. All measures could be assessed highly reliable with respect to intra- and inter-observer agreement. Breed type affected the width of the angle (F2, 114 = 8.20, p < 0.001), with thoroughbreds having the narrowest angle (M = 23.80, SD = 1.60), followed by warmbloods (M = 28.00, SD = 0.60), and coldbloods (M = 31.00, SD = 0.90). None of the other characteristics affected any of the outcome measures, and eye wrinkle expression did not differ between the left and the right eye area (all p-values > 0.05). In conclusion, horses' eye wrinkle expression and its assessment in neutral situations was not systematically affected by the investigated characteristics, except for 'breed type', which accounted for some variation in 'angle'; how much eye wrinkle expression is affected by emotion or perhaps mood needs further investigation and validation.
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Krueger, K. (2008). Social cognition and social learning in horses. In IESM 2008.
Abstract: In comparison to other social animals it appears to be far more difficult to show social learning in horses, although the social background of the animals prompts the prediction that social learning should be verifiable. This demands for a thorough analysis of conditions, context and effects of social learning which might not be as obvious in horses than in other social animals. Moreover, the horse“s social cognition in general, i.e. the processing, encoding, storage, retrieval, and application of social information, needs to be examined. In previous studies we addressed the horse”s perception of it“s social environment. Our results indicate that domestic horses are not only capable of distinguishing between familiar and unfamiliar horses but also of recognizing the social status of familiar horses relative to their own. Furthermore, they extract information from observing interactions between a familiar horse and a human experimenter, and adjust their behaviour according to the observed horse”s reaction and relative dominance status when they are themselves later confronted with the experimenter in a similar situation. Additionally, we showed in pilot experiments that horses paid more attention to the gaze of dominant horses from their own social group than to that of unknown or subordinate horses. In another study we suggested that horses of both sexes are capable of determining the social affiliation, the sex and, for their own group members, the identity of individuals, by sniffing their faeces. Hence, social affiliation and dominance relationships seemed to have a major influence on the horses` motivation to pay attention to their conspecifics. In the future we will take another step towards linking the horse“s social cognitive capacities with its social ecology, social structure, and individuality. In the context of comparative cognition research on the socially complex primates, or on a range of carnivores such as corvids, canids or dolphins, horses are particularly interesting, because they are highly social, but do not rely on social hunting or cooperative raising of offspring. Also foraging is simple for horses, predator avoidance is demanding and this may be the main reason for the horse”s complex social lives and their choice of learning tactics. Hence, we will investigate the horse"s investigative behaviour towards neutral, fear-eliciting and food related novel objects. We propose that, as in other species, sociality and distinct personalities are key features for the understanding of cognitive capacities and the choice of learning strategies.
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