Abstract: There is a paucity of research relating to the anatomy and physiology of gustation and olfaction in the horse. Moreover, whilst an age-related decline in gustation and olfaction has been recorded in humans, no such study has been conducted in the horse. The horse is reliant on gustation and olfaction to make appropriate decisions relating to both short and long term diet selection and thus, any compromise in function, has implications for food intake and potentially welfare. The principal aim of this study was to establish if, and to what extent, taste andgustatory responses are affected by age in the horse. Horses were allocated to the age groups Young (2-5 years), Middle (8-14 years) and Old (16 plus years) for the study of taste (n=18) and to Young (4-6 years), Middle (10-14 years) and Old (16 plus years) for the study of gustation (n=18). Individual taste responses and gustatory responses (taste in the absence of additional olfactory cues) were identified using two-choice preference testing and monadic testing. Statistical analysis was conducted using Minitab 14.0 and behaviour data was analysed using The Observer 5.0 (Noldus, Netherlands). No effect of age on taste response or gustatory response was recorded.

Abstract: In recent years, Przewalski’s horses have been increasingly kept in semi-reserves. However,there areonly few studies ontheir behaviour and their ability to adaptto management interventions.In the main part of my dissertation, I focus on investigatingthe animals’ behaviour in different semi-reserves with varyinghabitats and living spaces. In addition, I investigate the horses’ behaviour during various management interventionsand analysetheensuing changes instress levels. Another aspect of my dissertation is the studyof social behaviour inPrzewalski’s horses. I investigate theparameters that should be used to demonstrate social bonds between individualsandassess whichdata provide the most meaningful results.In the commentary tochapter 1,several studies investigatingsocial bonds in horsesare discussed. Comparing the various studies, it is strikingthat no homogeneous analyses orevaluation criteria exist. While some authors only considersocial grooming, others include data onthe spatial proximity of the individuals in their evaluations, and various definitionsof proximity can also be found in the literature. Additionally, someauthors use friendly approaches between individuals asa furtherparameter wheninvestigating the social bonds.Continuing with this theme, in chapter 2I investigate the social behaviour of the horses and compare various analysis methods. I show that proactive behaviour, such as friendly approaches, is a good alternative to spatial proximity when investigating social bonds between group members, andis also useful for expanding the often very small data sets of mutual grooming in horses. Comparing Przewalski’s horses with wild living horses, I found no significant differences in the social behavior and the frequency of social interactions, regardlessof group size, group composition, habitat, and individual parameters such as age and gender.Inchapter 3,I investigate the behaviour of a Przewalski’s horse group when exploring a new area of their enclosure. Their behaviour changed, showing less resting and more feeding. Furthermore, the animals maintained greater distances from each other, and the alpha male, instead of herding the group from behind, led the group around the new area and walked in front of the other group members. Moreover, he showed a substantial increase in stress level during the first day.A general comparison of the behaviour of the Przewalski’s horses in different semi-reserves is provided in chapter 4. In it, the habitat choice of the animals and their reactions to various management interventions are investigated. It is shown that Przewalski’s horses prefer open grassland to dense woods, although keeping Przewalski’s horses in a pine forest does not influence the animals’ stress level. In contrast to habitat, food range, and changes in the group composition, which do not appear to change stress levels, individual factors, such as the hierarchy, influence the glucocorticoid level of the animals significantly. The largest increases in stress hormones were demonstrated when the horses were temporarily confined in smaller areas.The importance of the available space is also discussed in chapter 5, where it is shown that horses show less aggressive behaviour when more space is provided. In contrast, the husbandry system does not influence the animals’ aggression, but the way of feeding can additionally reduce agonistic behaviour, for example if food is offered ad libitum.In summary, the results of this study provide indications for the optimization of keeping Przewalski’s horses in semi-reserves. The animals can adapt themselves to the environment and thrive in habitats which do not correspond to their original steppe-like home. Nevertheless, the semi-reserves should provide sufficient grassland, as the horses prefer this type of habitat. General speaking, any types of habitat can only offer a suitable living space if the food range is sufficient for the number of horses. Otherwise, and especially during could winter months, supplementary feeding is necessary according to the body condition of the animals. This is particularly important for older, weakened, or very young animals, which are still adapting to life in the semi-reserve. Without sufficient food, stress hormones can increase and negatively influence the well-being of the horses. The same is true for management interventions: restricting the animals to small enclosures, for example, can adversely affect the horses’ well-being and should be only done if absolutely necessary. Targetedbehaviour observations allow the animals that have a special meaning for the group to be identified, and these should not be taken out of the group unless it is unavoidable, as young and unexperienced horses orientate themselves on those animals. This is especially true for the alpha male in a bachelor group, as these groups are often composed of young horses and the alpha-male provides the necessary stability and experience. Social bonds between individuals can be investigated by observing friendly and proactive behaviour, and social grooming and friendly approaches yield suitable data for such analysis.

Abstract: Ziel der Studie war die Beschreibung der motorischen Lateralität („Schiefe“) gesunder adulter Pferde. Hierzu wurden 14 lahmfreie Pferde (10 Warmblüter, 4 Quarter Horses) auf dem Laufband in Schritt und Trab auf individuelle Abweichungen von der symmetri-schen Bewegung hinsichtlich Abstellung der Hinterhand, Wirbelsäulenform (Biegung), Vor- und Rückführung sowie Belastung von Vorder- und Hintergliedmaßen jeweils simul-tan hochfrequenzkinematographisch und kinetisch mittels resistiver Hufdrucksensoren untersucht. Zusätzlich wurden bevorzugte Abstellung und Biegung sowie Galopppräfe-renz klinisch bzw. reiterlich beurteilt, das Vorliegen einer Weideschrittpräferenz unter-sucht und Freilaufversuche (bevorzugte Abbiegerichtung, Ausweichrichtung um ein Hin-dernis, Galoppräferenz) durchgeführt. Keines der Pferde zeigte Symmetrie über alle Merkmale; zwar wurde bei jedem Merkmal für einzelne Probanden Symmetrie festgestellt, mit Ausnahme des Galopp-Freilaufver-suchs trat Asymmetrie jedoch häufiger auf. 12 Probanden zeigten in der Bewegungsana-lyse eine signifikante seitliche Abstellung (8x rechts (R), 4x links (L), mittlere seitliche Abweichung im Schritt 1,22°±1,09°, im Trab 1,05°±1,03°), 10 eine bevorzugte Biegung (9x L, 1x R), 13 signifikante Asymmetrien der Gliedmaßenvor- bzw. -rückführung und 12 eine signifikante asymmetrische Gliedmaßenbelastung für die normalisierte Spitzenkraft (PFN, peak force) bzw. den Impuls der Belastung (IN) an mindestens einem Beinpaar (alle Merkmale individuell wiederholbar). Linksabgestellte Pferde führten in beiden Gang-arten das rechte Hinterbein signifikant weiter zurück als nach rechts abgestellte Pferde, die tendenziell eher das linke Hinterbein weiter zurückführten. – Die auf dem Laufband festgestellten Asymmetrien traten in beiden Gangarten auf, aber nicht immer überein-stimmend, wobei die Richtung der bevorzugten Abstellung und ebenso der bevorzugten Biegung beim einzelnen Pferd in Schritt und Trab nie gegensätzlich waren. Jeder dieser beiden Parameter wurde daher für das einzelne Pferd über beide Gangarten zusammen-gefasst. Die Richtung von Abstellung und Biegung waren voneinander unabhängig, so-dass die Bewegungsmuster Abstellung ohne Biegung, Biegung ohne Abstellung, Abstel-lung mit Biegung in Laufrichtung (Travers) sowie Abstellung mit Biegung entgegen der Laufrichtung (Schulterherein) vorkamen. Kein Pferd war in beiden Merkmalen symmet-risch; für manche Pferde war neben der einfachen Biegung auch eine S-Form der Wir-belsäule signifikant. Die Belastungssymmetrie der Gliedmaßen war in beiden Gangarten von der Abstellung und der Biegung unabhängig, es gab aber Hinweise auf Zusammen-hänge zwischen bestimmten Kombinationen von Abstellung und Biegung einerseits und der Existenz einer Belastungsasymmetrie der Vorderbeine im Trab andererseits (unge-bogen mit Abstellung laufende und im Schulterherein laufende Pferde belasteten i.d.R. asymmetrisch).
8 Pferde wiesen eine signifikante Weideschrittpräferenz auf (5x L, 3x R), die bei ebenso vorhandener seitlicher Abstellung signifkant häufiger auf der der Abstellung abgewandten Seite auftrat. Sie wies keinen Zusammenhang mit der Rückführung der Hinterbeine im Schritt oder im Trab auf. Das Auftreten einer Weideschrittpräferenz war signifikant vom durch Abstellung und Biegung bestimmten Bewegungsmuster abhängig (Auftreten bei Abstellung ohne Biegung und bei Schulterherein, nicht bei Travers oder Biegung ohne Abstellung). Zudem zeigt die Präferenz der Pferde im Weideschritt eine starke Überein-stimmung mit der Belastungssymmetrie der Vorderbeine im Trab (bevorzugt vorgestelltes Bein wird mehr belastet (IN); symmetrische Belastung bei fehlender Präferenz). Im Hindernisversuch hatten 12 von 13 getesteten Probanden eine signifikant bevorzugte Ausweichrichtung (5x L, 7x R); diese war unabhängig von der gemessenen Wirbelsäulenform, lag aber bei Pferden mit seitlicher Abstellung überwiegend auf der Seite der gemessenen Abstellung. Im Abbiegeversuch zeigten 6 von 12 getesteten Probanden eine signifikant bevorzugte Abbiegerichtung (3x L, 3x R), diese war weder von der Abstellungsrichtung noch von der Wirbelsäulenform, der Weideschrittpräferenz oder der Belastungssymmetrie der Vorderbeine im Trab abhängig. Die meisten Pferde zeigten im Freilauf keine signifikante Galopppräferenz (2x L, 11x gerade (N), 1x R), wogegen reiterlich bei den meisten Pferden eine Präferenz festgestellt wurde; beide Beurteilungen stimmten ebenso wie die Beurteilungen verschiedener Reiter nicht miteinander überein. Die gemessene Abstellungsrichtung ließ sich durch visuelle Beobachtung mit hoher Si-cherheit vorhersagen. Die bevorzugte Wirbelsäulenform stimmte nicht mit der reiterlich oder an der Longe festgestellten Biegung überein, wohl aber mit der Seite, auf die die Mähne fällt. Die vorliegende Studie weist nach, dass individuell stabile motorische Lateralität, weitge-hend bestehend aus den den Merkmalen der reiterlich postulierten „Schiefe“, bei gesun-den Pferden in symmetrischen Gangarten besteht und dass zwischen bestimmten Merkmalen vorhersagbare Zusammenhänge bestehen. Daraus ergeben sich wertvolle Schlussfolgerungen für das reiterliche Geraderichten des Pferdes, für das in Übereinstimmung mit der Reitliteratur insbesondere die Lektion Schulterherein geeignet erscheint. Es ist gelungen, für die wesentlichen Merkmale Abstellung, Biegung und Belastungssymmetrie der Vordergliedmaßen im Trab klinische Tests aufzuzeigen, die mit hoher Sicher-heit die Ergebnisse der Bewegungsanalyse vorhersagen können, wobei Rückschlüsse auf weitere asymmetrische Merkmale möglich sind. Die reiterliche Beurteilung von bevor-zugter Biegung und Galopppräferenz scheint jedoch von weiteren Faktoren außer dem Pferd selbst abhängig zu sein und stimmt häufig nicht mit den messbaren Parametern überein. – In dieser Studie wird erstmals eine wissenschaftlich überprüfte und klinisch anwendbare Methode zur umfassenden Analyse der motorischen Lateralität im Sinne der „Schiefe“ eines Pferdes beschrieben.
Summary -“Crookedness“ in the Horse: Symmetry of Motion and Hoof Loading
The purpose of this study was description of motor laterality (in terms of “crookedness“) of sound adult horses. 14 non-lame horses (10 Warmblood horses, 4 Quarter Horses) were examined walking and trotting on a treadmill for individual motion asymmetry concerning keeping the hindlimbs at an angle (hindlimbs not tracking the frontlimbs, “hindquarter angle”), lateroflexion, pro- and retraction of the limbs as well as loading of front- and hindlimbs. High-speed-kinematography and resistive pressure sensors were used simultanously. The horses were also ridden to evaluate preferred lateroflexion and preferred lead in canter. Moving at an angle towards a preferred side was assessed visually. Laterality of grazing stance was tested, as well as preferred turning direction, obstacle avoidance direction and preferred lead in canter while moving unrestrained in an arena. None of the horses moved symetrically over all traits; although there were symmetrical traits with individual horses, asymmetry was more commen (except for the unrestrained preferred lead test). On the treadmill, 12 horses moved with their hindquarters significantly at a angle (8x right (R), 4x left (L), mean lateral angle 1,22°±1,09° at a walk and 1,05°±1,03° at a trot), 10 showed laterality for lateroflexion (9x L, 1x R), 13 had significant asymmetries for protraction and/ or retraction and 12 for loading of contralateral limbs concerning normalized peak force (PFN) and impulse (IN), respectively, of at least one pair of limbs (all with good repeatibility). Horses keeping their hindquarters to the left showed significantly larger retraction of the right hindlimb compared to horses keeping their hindquarters to the right, who tended to further retract the left hindlimb. – Asymmetries found on the treadmill occurred in both gaits but were not always the same in both gaits, though the direction of the hindquarter angle as well as that of the preferred lateroflexion never contradicted each other within the same individual. Therefore, a specific laterality direction of hindquarter angle and lateroflexion could be assigned to each horse. The direction of preferred hindquarter angle and lateroflexion, respectively, were independent of each other so that the movement patterns “hindquarter angle without lateroflexion”, “lateroflexion without hindquarter angle”, “hindquarter angle with lateroflexion to the same side” (hindquarter-in/ travers) and “hindquarter angle with lateroflexion to opposite sides” (shoulder-in) could be found; no horse moved symmetrical for both traits. The lateroflexion of some horses could even be regarded as a double bend. At both gaits, symmetry of limb loading was independent of hindquarter angle as well as lateroflexion, taken seperately; still, there seems to be a relation between certain combinations of hindquarter angle and lateroflexion, on the one side, and the existence or absence of asymmetric loading of the frontlimbs in trot (horses moving with hindquarter angle, but without lateroflexion, and horses moving in shoulder-in mostly had asymmetric frontlimb loading).
238 7. Summary8 horses displayed laterality for a grazing stance (5x L, 3x R); their hindquarter angle, if they showed one, was significantly more often on the opposite side of their advanced frontleg while grazing. The direction of the grazing stance was independent of hindlimb retraction symmetry in either gait. Occurrence of grazing stance laterality significantly depended on the movement pattern consisting of hindquarter angle and lateroflexion (horses moving with a hindquarter angle, but without lateroflexion, and horses moving in shoulder-in mostly showed grazing stance laterality, while horses moving with lateroflexion, but without a hindquarter angle, and horses moving in hindquarter-in did not). Also, grazing stance laterality was highly predictive of the symmetry of frontlimb loading at trot (advanced frontleg has significantly higher impulse (IN) at trot; horses without grazing stance laterality showed symmetrical impulse). 12 of 13 horses displayed laterality for obstacle avoidance direction (5x L, 7x R) that was independent of the individually preferred lateroflexion but if the horses showed a hindquarter angle it was usually to the same side. 6 of 12 horses showed laterality for turning direction (3x L, 3x R) that had no relation to laterality of either hindquarter angle, lateroflexion, grazing stance or frontlimb loading symmetry at trot. Most horses had no significant lead preference in the unrestrained canter test (2x L, 11x no preference (N), 1x R) even though riders assigned a lead preference to most horses; both ratings did not match, as well as the rating between two different riders did not match. The (measured) direction of hindquarter angle was highly predictable by visual asessment. Preferred (measured) lateroflexion did not match the direction of lateroflexion assigned by either rider or on the long line; it was in agreement with the mane side of the horse, though. This study proves that individual and stable motor laterality exists in sound horses in symmetrical gaits, mostly consisting of the traits that are hypothesized as “crookedness” in riding literature. It also shows that predictible relationships exist between certain traits thereof. This knowledge is valuable since it has implications for the training of riding horses for straightness, wherefore especially riding shoulder-in should be helpful. Relatively easy clinical tests could successfully be found that allow well predicting main features of individual horses ́ motor laterality like hindquarter angle, lateroflexion and frontlimb loading symmetry at trot as measured on the treadmill. Some conclusions can also be drawn for other asymmetrical traits. The asessment of preferred lateroflexion and canter lead performed by riders, though, seems to also underlie other influences than the horse itself and failed to be a predictor of the measured traits. – For the first time, a scientifically proven and clinically applicable method of asessing a horses motor laterality in terms of “crookedness” is presented.