Abstract: Prima facie, the acquisition of novel behaviors in animals through observation of conspecifics seems straightforward. There are, however, various mechanisms through which the behavior of animals can be altered from observing others. These mechanisms range from simple hard-wired contagious processes to genuine learning by observation, which differ fundamentally in cognitive complexity. They range from social facilitation and local enhancement to true social learning. The different learning mechanisms are the subject of this review, largely because research on learning by observation can be confounded by difficulties in interpretation owing to the looming possibility of associative learning infecting experimental results. While it is often assumed that horses are capable of acquiring new behavior through intra-species observation, research on social learning in horses includes a variety of studies some of which may overestimate the possession of higher mental abilities. Assuming such abilities in their absence can have welfare implications, e.g. isolating stereotypical horses on the assumption that these behaviors can be learned though observation by neighboring horses. This review summarizes the definitions and criteria for the various types of social transmission and social learning and reviews the current documentation for each type in horses with the aim of clarifying whether horses possess the ability to learn through true social learning. As social ungulates, horses evolved in open landscapes, exposed to predators and grazing most of the day. Being in close proximity to conspecifics may theoretically offer an opportunity to learn socially, however anti-predator vigilance and locating forage may not require the neural complexity of social learning. Given the significant energetic expense of brain tissue, it is likely that social facilitation and local enhancement may have been sufficient in the adaptation of equids to their niche. As a consequence, social learning abilities may be maladaptive in horses. Collectively, the review proposes a novel differentiation between social transmission (social facilitation, local and stimulus enhancement) and social learning (goal emulation, imitation). Horses are undoubtedly sensitive to intra-species transfer of information but this transfer does not appear to satisfy the criteria for social learning, and thus there is no solid evidence for true social learning in horses.

Abstract: The aim of this study was to conduct a series of paper-based exercises in order to assess the negative (adverse) welfare impacts, if any, of common interventions on domestic horses across a broad range of different contexts of equine care and training. An international panel (with professional expertise in psychology, equitation science, veterinary science, education, welfare, equestrian coaching, advocacy, and community engagement; n = 16) met over a four-day period to define and assess these interventions, using an adaptation of the domain-based assessment model. The interventions were considered within 14 contexts: C1 Weaning; C2 Diet; C3 Housing; C4 Foundation training; C5 Ill-health and veterinary interventions (chiefly medical); C6 Ill-health and veterinary interventions (chiefly surgical); C7 Elective procedures; C8 Care procedures; C9 Restraint for management procedures; C10 Road transport; C11 Activity—competition; C12 Activity—work; C13 Activity—breeding females; and C14 Activity—breeding males. Scores on a 1–10 scale for Domain 5 (the mental domain) gathered during the workshop were compared with overall impact scores on a 1–10 scale assigned by the same panellists individually before the workshop. The most severe (median and interquartile range, IQR) impacts within each context were identified during the workshop as: C1 abrupt, individual weaning (10 IQR 1); C2 feeding 100% low-energy concentrate (8 IQR 2.5); C3 indoor tie stalls with no social contact (9 IQR 1.5); C4 both (i) dropping horse with ropes (9 IQR 0.5) and forced flexion (9 IQR 0.5); C5 long-term curative medical treatments (8 IQR 3); C6 major deep intracavity surgery (8.5 IQR 1); C7 castration without veterinary supervision (10 IQR 1); C8 both (i) tongue ties (8 IQR 2.5) and (ii) restrictive nosebands (8 IQR 2.5); C9 ear twitch (8 IQR 1); C10 both (i) individual transport (7.00 IQR 1.5) and group transport with unfamiliar companions (7 IQR 1.5); C11 both (i) jumps racing (8 IQR 2.5) and Western performance (8 IQR 1.5); C12 carriage and haulage work (6 IQR 1.5); C13 wet nurse during transition between foals (7.5 IQR 3.75); and C14 teaser horse (7 IQR 8). Associations between pre-workshop and workshop scores were high, but some rankings changed after workshop participation, particularly relating to breeding practices. Domain 1 had the weakest association with Domain 5. The current article discusses the use of the domain-based model in equine welfare assessment, and offers a series of assumptions within each context that future users of the same approach may make when assessing animal welfare under the categories reported here. It also discusses some limitations in the framework that was used to apply the model.

Abstract: Cerebral lateralization, i.e. hemispheric asymmetries in structure and function, relates in many species to a preference to attack from their left. Lateralization increases cognitive capacity, enabling the simultaneous processing of multiple sources of information. Therefore, lateralization may constitute a component of fighting ability (Resource Holding Potential), and/or influence the efficiency of information-gathering during a contest. We hypothesized that lateralization will affect contest outcome and duration, with an advantage for more strongly lateralized individuals. In 52 dyadic contests between weight-matched pigs (Sus scrofa; n = 104; 10 wk age), the direction of orientation towards the opponent was scan sampled every 10 s. Laterality indexes (LI) were calculated for the direction and strength of lateralization. Up to 12.5% of the individuals showed significant lateralization towards either the right or left but lateralization was absent at the population level. In line with our hypothesis, animals showing strong lateralization (irrespective of direction) had a shorter contest duration than animals showing weak lateralization. Winners did not differ from losers in their strength or direction of lateralization. Overall the results suggest that cerebral lateralization may aid in conflict resolution, but does not directly contribute to fighting ability, and will be of value in the study of animal contests.

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.