Abstract: Horses are a highly social species living in complex social systems which should require them to memorise and generalise social experiences and distinguish between familiar and unfamiliar conspecifics. In the main part of my thesis I concentrated on the specific conflict situation of a horse being introduced into a new social group, and investigated its behaviour and stress level. Horses were either introduced (1) immediately, (2) after an observation period, or (3) together with an integration horse after an observation period. Additionally, in the second part of my thesis I arranged several experiments to elaborate additional aspects which could affect the behaviour of horses during introductions. In this study I could describe a simplified method for measuring stress through the analysis of faecal GCMs in horses. An enzyme immunoassay (EIA) for 11-oxoaetiocholanolone using 11-oxoaetiocholanolone-17-CMO: BSA (3?,11-oxo-A EIA) as antigen showed high amounts of immunoreactive substances. The new assay increases the accuracy of the test and lowers the expenses per sample; also storing of samples at room temperature after collection is less critical. This is a big advantage both in the field of wildlife management of equids and in the field of equestrian sports (chapter 1). Comparing the different introduction techniques, the introduction with an integration horse led to significantly less total interactions and lower levels of aggression than the introduction of single horses, both immediately and after several days of observing the new group. Additionally, by observing the behaviour of the horses during everyday sociality I could develop a formula describing the interrelationship between expected aggression level and enclosure size per horse. The curve takes an exponential shape. Starting from a space allowance of 300 m2 and more per horse, the amount of aggressions per hour approaches zero. For the reduction of aggression levels and injury risks in socially kept horses I recommend an enclosure size of at least 300 m2 per horse (chapter 2). I further investigated the stress level of the introduced animals. Horses which were immediately introduced did not show elevated faecal GCMs. In contrast, horses which were introduced after an observation period had slightly elevated values 2 and 3 days after the introduction. For horses introduced together with an integration horse faecal GCMs were significantly above the baseline value on the day of introduction and 1 day after it. These differences between introduction techniques indicate that the introduction event itself is not as stressful as previously assumed. Rather standing together with an integration horse and not being able to integrate immediately into the complete group elicits stress in horses (chapter 3). In the commentary of chapter 4 several studies are discussed which failed to demonstrate social learning in horses. It is argued that they did not consider important aspects which could have an influence, such as the dominance status or the social background of the horses (chapter 4). In chapter 5 a social feeding situation was investigated. The social rank as well as the position of conspecifics affected the feeding strategy of horses. Domestic horses used social cognition and strategic decision making in order to decide where to feed. When possible they tended to return to the same, continuously supplied feeding site and switched to an ?avoidance tendency? in the presence of dominant horses or when another horse was already feeding there (chapter 5). One possibility to recognize group members is through olfactory recognition. In chapter 6 it is shown that horses are able to distinguish their own from their conspecifics? faeces. In addition, they paid most attention to the faeces of those group members from which they received the highest amount of aggressive behaviour (chapter 6). Horses show cognitive abilities because they are able to use humans as local enhancement cues when searching for food, independently of their body posture or gaze consistency when the persons face them. Moreover, they seem to orientate on the attention of familiar persons more than of unfamiliar persons (chapter 7). Altogether, the results of this thesis provide further support for the view that horses show good conflict resolution strategies. They are perfectly able to deal with the conflict situation of being introduced to new group members, and the introduction event itself is not as stressful as previously assumed. It is rather suggested that standing together with an integration horse and not being able to integrate immediately into the complete group elicits stress in horses. All additional experimental set-ups could demonstrate that horses are well capable of social cognition.

Abstract: The purpose of this study is to find convincing arguments, how horses should be ridden correctly, especially concerning the best head and neck position. Currently in the riding world, the opinions differ: The traditional way is to ride a horse with its nose in front of the vertical, while a new method claims that pulling the nose behind the vertical with an extreme flexion of the poll implies “gymnastic movements”. This article is focussed on the welfare and comfort of the horse in different head-neck positions, expressed by behaviours which document discomfort. As a first step, the behaviour of standing horses was observed while their heads and necks were put into seven postulated or frequently assumed positions. In the hyperflexed position the horses displayed most discomfort (with 49,7% of all reactions, like open mouths, head tossing, tail movements and other signs of resentment). The second strongest reactions of discomfort were shown in the highly raised position of the head (34,9%). The moderately rounded neck position as in traditional dressage lessons was not without signs of discomfort either, but less than the other two positions (11,2%). The high position and the extended position did not cause discomfort at all (0,17% and 0,23% respectively). In a second step, horses moving in all gaits under a rider were observed at competitions without the riders´ knowledge. The total number of observations was divided into two categories (each containing 30 horses) on the basis of the common rules of the FN: ridden with the horse’s nose in front of the vertical and ridden with the horse’s nose behind the vertical. The proportion of horses showing discomfort with the nose behind the vertical was clearly much higher (89,3%) compared to those ridden with the nose in front of the vertical (10,7%). Thus, the horses in the first category displayed signs of discomfort 8 times more frequent than those in the second group. In addition, scans carried out at tournaments showed that 92.8% of the horses were ridden with the nose behind the vertical. A clear result of this study is that the reality of riding differs widely from the rules. These results also show that riding in the hyperflexed position causes a great deal of discomfort for the horses and therefore should be abolished.
Die aktuellen Diskussionen in der Reiterwelt, welche Art und Weise des Reitens, besonders welche Kopf-Hals-Stellung zu erstreben ist, werfen die Frage auf, ob und wie die Pferde selbst ihr Befinden zum Ausdruck bringen. Über die Empfindungen der Pferde in verschiedenen Kopfhaltungen ist bisher sehr wenig bekannt. Deswegen wurde zunächst an stehenden Pferden das Ausdrucksverhalten beobachtet. Missfallensäußerungen häuften sich (mit 49,7% aller gezeigten Verhaltensauffälligkeiten wie Sperren, Rückwärtsgehen und Kopfschlagen) in der aufgerollten, hyperflektierten Stellung des Halses. An zweiter Stelle folgten Unmutsäußerungen in der absolut aufgerichteten Haltung (34,9%). Auch die beigezäumte Haltung wurde nicht ohne Unmutsbekundungen hingenommen, hier war deren Anzahl aber wesentlich geringer (11,2%). Die hohe Kopfstellung (0,17%) und die Dehnungshaltung (0,23%) bereiteten den Tieren kaum Unbehagen. Auch das Ausdrucksverhalten der Pferde unter dem Reiter wurde untersucht. Hierfür wurden, unter Berücksichtigung der schriftlich fixierten Regeln für das Turnierwesen der FN, je 30 Pferde in zwei Kategorien beobachtet: mit der Stirnlinie vor der Senkrechten und Pferde mit der Stirnlinie hinter der Senkrechten. Die Beobachtungen wurden unbemerkt von den Reitern auf den Abreiteplätzen von Turnieren durchgeführt. Die Anzahl an Verhaltensauffälligkeiten der Pferde mit der Stirnlinie hinter der Senkrechten war deutlich (89,3 %) erhöht im Gegensatz zu der anderen Gruppe (10,7 %). Die Pferde mit der Stirnlinie hinter der Senkrechten zeigten 8 Mal mehr Unmutsäußerungen als die mit der Stirnlinie vor der Senkrechten. Entgegen den Regeln der FN zeigten die durchgeführten Scans, dass unmittelbar vor den Prüfungen auf Turnieren 92,8% der Pferde mit der Stirnnasen-Linie hinter der Senkrechten geritten wurden. Ein Befund dieser Studie ist die Feststellung, dass die Praxis deutlich von den Regeln abweicht. Das Reiten mit der Stirnlinie hinter der Senkrechten ist nach diesen Befunden abzulehnen, da die Pferde deutliches Unwohlsein in dieser Haltung signalisieren.

Abstract: This study investigated the horse’s contribution to tension in the reins. The experimental hypotheses were that tension in side reins (1) increases biphasically in each trot stride, (2) changes inversely with rein length, and (3) changes with elasticity of the reins. Eight riding horses trotted in hand at consistent speed in a straight line wearing a bit and bridle and three types of side reins (inelastic, stiff elastic, compliant elastic) were evaluated in random order at long, neutral, and short lengths. Strain gauge transducers (240 Hz) measured minimal, maximal and mean rein tension, rate of loading and impulse. The effects of rein type and length were evaluated using ANOVA with Bonferroni post hoc tests. Rein tension oscillated in a regular pattern with a peak during each diagonal stance phase. Within each rein type, minimal, maximal and mean tensions were higher with shorter reins. At neutral or short lengths, minimal tension increased and maximal tension decreased with elasticity of the reins. Short, inelastic reins had the highest maximal tension and rate of loading. Since the tension variables respond differently to rein elasticity at different lengths, it is recommended that a set of variables representing different aspects of rein tension should be reported.

Abstract: The aim of this study was to investigate the use of items intended to provide enrichment during turnout, both for individual and group kept horses in an attempt to reduce the amount of passive behaviours. The study was divided into two parts, where study 1 involved eight horses rotated through eight individual paddocks, each containing one of seven enrichment items and one paddock being kept without item, functioning as a control. The horses' item-directed behaviours; passive behaviours or other non-item related activities were scored using instantaneous sampling, every minute for 1h at the beginning and the end of the turnout period. Study 2 involved six horse groups (3-6 horses) and the same scoring methods and ethogram as in study 1. The four items that the horses interacted the most with during study 1 (straw STRA, ball filled with concentrates CBALL, branches BRAN and scratching pole POLE) are investigated in study 2. In addition, the amount of social interactions was recorded. Both horses kept individually (P<0.05) and in groups (P<0.0001) performed significantly more item-directed behaviours towards edible items like STRA and CBALL than other objects. There was, however, no overall relation between the numbers of item-directed behaviours and the number of passive behaviours observed, indicating that the enrichment items did not alone reduce the amount of passive behaviours during turnout periods. Such a reduction was, however, only apparent when horses spent more time eating green leaves growing on the paddock surface (R=-0.97 study 1, R=-0.67 study 2, P<0.0001). Access to STRA in group kept horses also seemed to reduce the amount of agonistic behaviours (P<0.0001). In conclusion, if grass is not available in paddocks, the provision of roughage reduces the amount of passive behaviours in singly kept horses and it also reduces the risk of agonistic interactions between horses kept in group.

Abstract: A total of 17 microsatellite deoxyribonucleic acid loci used routinely for horse parentage control were used to evaluate genetic diversity among normal Arabian horses and severe combined immunodeficiency (SCID) carrier Arabian horses (ArS) and normal Arab-Barb horses and SCID carrier Arab-Barb horses (ArbeS). On the basis of the genotype of 186 horses, mean allelic diversity was estimated as 6.82, 5.53, and 6.7059 in normal Arabian horses, ArS, and for both groups of Arab-Barb horses, respectively. Five specific alleles were observed in ArS and ArbeS, with one common with ArS at HMS6, whereas five alleles common between ArS and ArbeS had a high frequency. Expected and observed heterozygosity showed great heterogeneity in the population studied and were similar or higher when compared with other studies on Arabian horses. Coefficient of gene differentiation Gst of Nei associated with Nei's genetic distance and multivariate correspondence analysis indicated a possible differentiation between the studied populations when analyzed separately according to breed. Probability of assignment of a horse to a specific group was assessed using a full and partial Bayesian approach. In all, 80.6% of Arab horses and 78.2% of Arab-Barb horses were assigned properly with a partial Bayesian test, which provided better results than the full one. These findings will be useful for identification of SCID carrier horses by using the microsatellite deoxyribonucleic acid loci used routinely for horse parentage control in our laboratory.