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Leliveld, L. M. C., Düpjan, S., Tuchscherer, A., & Puppe, B. (2020). Hemispheric Specialization for Processing the Communicative and Emotional Content of Vocal Communication in a Social Mammal, the Domestic Pig. Front. Behav. Neurosci., 14, 596758.
Abstract: In humans, speech perception is lateralized, with the left hemisphere of the brain dominant in processing the communicative content and the right hemisphere dominant in processing the emotional content. However, still little is known about such a division of tasks in other species. We therefore investigated lateralized processing of communicative and emotionally relevant calls in a social mammal, the pig (Sus scrofa). Based on the contralateral connection between ears and hemispheres, we compared the behavioural and cardiac responses of 36 young male pigs during binaural and monaural (left or right) playback to the same sounds. The playback stimuli were calls of social isolation and physical restraint, whose communicative and emotional relevance, respectively, were validated prior to the test by acoustic analyses and during binaural playbacks. There were indications of lateralized processing mainly in the initial detection (left head-turn bias, indicating right hemispheric dominance) of the more emotionally relevant restraint calls. Conversely, there were indications of lateralized processing only in the appraisal (increased attention during playback to the right ear) of the more communicative relevant isolation calls. This implies differential involvement of the hemispheres in the auditory processing of vocalizations in pigs and thereby hints at similarities in the auditory processing of vocal communication in non-human animals and speech in humans. Therefore, these findings provide interesting new insight in the evolution of human language and auditory lateralization.
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Lesimple, C., Reverchon-Billot, L., Galloux, P., Stomp, M., Boichot, L., Coste, C., et al. (2020). Free movement: A key for welfare improvement in sport horses? Appl. Anim. Behav. Sci., 225, 104972.
Abstract: Horses, and in particular sport horses, remain housed predominantly in single stalls. One of the main reported reasons is the fear that they will become agitated and injure themselves and thereby impair their performance if released in paddocks. The hour spent daily at work is also assumed to be sufficient to satisfy the horses' needs for locomotion. Growing scientific evidence shows that single stall housing has negative consequences on horses' welfare and that time for free movement is necessary. Our aim was to assess the feasibility of allowing sport horses used to staying permanently in their stall (except for 1 h riding/day) daily free time in a paddock and to evaluate its potential impact on their welfare using two behavioural reliable indicators (stereotypic behaviours and ear position), as well as selected blood parameters (blood cell count, oxytocin and serotonin concentrations). Two experiments were conducted on the same site. The first experiment evaluated sport horses' habituation to the novel situation of daily sessions in a paddock, and recorded welfare indicators in their stall before and during the experiment, comparing horses that were taken outdoors (experimental) and those that stayed in their stall (control). The second experiment evaluated the impact of this daily free time in a paddock on horses' welfare and its durability, focusing on positive indicators. Behavioural observations in paddocks showed that even horses that had never experienced free movement outside their stall habituated rapidly to this situation. The presence of hay in the paddock, may have speeded up habituation. Their restricted living conditions were associated with abnormalities in blood cell count that were not overcome during the time of daily paddock sessions but behavioural indicators showed that their welfare improved. In the second study, the experimental horses' welfare improved during the paddock release period, in particular their stereotypic behaviours decreased and oxytocin levels increased. No effects on serotonin concentrations could be evidenced. These effects were directly associated with being in paddock, as the indicators returned rapidly to their previous levels indicating compromised welfare when the paddock release sessions stopped. In conclusion, it can be recommended to release sport horses for free movement in paddocks as welfare is improved and subjective assessment by caretakers indicated minimal risks.
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Marr, I., Preisler, V., Farmer, K., Stefanski, V., & Krueger, K. (2020). Non-invasive stress evaluation in domestic horses (Equus caballus): impact of housing conditions on sensory laterality and immunoglobulin A. Royal Society Open Science, 7(2), 191994.
Abstract: The study aimed to evaluate sensory laterality and concentration of faecal immunoglobulin A (IgA) as non-invasive measures of stress in horses by comparing them with the already established measures of motor laterality and faecal glucocorticoid metabolites (FGMs). Eleven three-year-old horses were exposed to known stressful situations (change of housing, initial training) to assess the two new parameters. Sensory laterality initially shifted significantly to the left and faecal FGMs were significantly increased on the change from group to individual housing and remained high through initial training. Motor laterality shifted significantly to the left after one week of individual stabling. Faecal IgA remained unchanged throughout the experiment. We therefore suggest that sensory laterality may be helpful in assessing acute stress in horses, especially on an individual level, as it proved to be an objective behavioural parameter that is easy to observe. Comparably, motor laterality may be helpful in assessing long-lasting stress. The results indicate that stress changes sensory laterality in horses, but further research is needed on a larger sample to evaluate elevated chronic stress, as it was not clear whether the horses of the present study experienced compromised welfare, which it has been proposed may affect faecal IgA.
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Osman, F., Zeitler-Feicht, M., Fink, G. W., Arnhard, S., & Krüger, K. (2020). Überprüfung der lichten Weiten von Gitterstäben in der Pferdehaltung [Analysing demands for the clear widths of lattice bars in horse husbandry]. Landtechnik [Agricultural Engineering], 75(1), 24–33.
Abstract: An Gitterstäben, die in der Pferdehaltung an verschiedenen Stellen verwendet werden, können sich Pferde verletzen, wenn sie ihre Köpfe oder ihre Hufe hindurchstecken und nicht zurückziehen können. Um das Verletzungsrisiko zu reduzieren sind lichte Weiten und Materialstärken von Gitterstäben so zu wählen, dass Pferdeköpfe und -hufe entweder nicht zwischen den Freiräumen hindurchpassen oder aber gefahrlos wieder zurückgezogen werden können. Die bisherige Forschung liefert jedoch keine belastbaren Aussagen zu Stababständen (senkrecht und waagerecht), die für Pferde ungefährlich sind. Die in der Praxis verwendeten und in der Literatur empfohlenen Gitterstababstände beruhen auf Erfahrungswerten und technischen Materialeigenschaften. In der vorliegenden Untersuchung wurden Pferdeköpfe und -hufe von insgesamt 480 Pferden (233 Stuten, 204 Wallache und 43 Hengste) von 23 verschiedenen Rassen vermessen, um auf Grundlage der Anatomie der Pferde Aussagen über die Eignung von marktüblichen Stababständen in der Praxis treffen zu können. Es stellte sich heraus, dass bei senkrechten Gitterstäben eine lichte Weite von nicht mehr als 5 cm für alle Pferde ab einem Stockmaß von 110 cm und einem Alter von zwei Jahren als sicher bezeichnet werden kann. Bei waagerechten Gitterstäben erwies sich eine lichte Weite von genau 17 cm als sicher. Dies gilt für alle Pferde ab einem Alter von zwei Jahren oder ab einem Stockmaß von 148 cm.
Kritisch sind die lichten Weiten von Panels zu beurteilen. Hier zeigte sich, dass die handelsüblichen Abstände der Gitterstäbe für die meisten Pferde eine erhebliche Gefahr darstellen. Wenn die Pferde beispielsweise versuchen außerhalb der Panels zu fressen und dabei ihren Kopf durch die Gitterstäbe stecken, kann es leicht passieren, dass sie sich mit dem Kopf zwischen den Gitterstäben verklemmen.
[At bars, used in various places in horse husbandry, horses can hurt themselves when retracting their heads or hooves after pushing them through the interspaces. In order to reduce the risk of injury, the clear widths and material thicknesses of bars should be chosen so that horse heads and hooves either cannot pass between the spaces or can be retracted safely. However, research to date has not provided any reliable information on bar width (vertical and horizontal) that is safe for horses. Grid bar width used in practice and recommended in the literature is based on empirical values and technical material properties. In this study, heads and hooves of 480 horses (233 mares, 204 geldings and 43 stallions) of 23 breeds were measured for making statements about the suitability of standard bar width, when considering the anatomy of the horse. It turned out that for vertical bars, an interspace of no more than five centimetres can be considered to be safe for all horses of a height of 110 centimetres and an age of two years and more. With horizontal lattice bars, a clear width of exactly 17 centimetres proved to be safe. This applies to all horses of a height of 148 centimetres and an age of two years or more. The clear widths of panels must be considered critical for horse welfare. When horses, for example, try to eat outside the panels and put their head through the bars, they may get stuck.]
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Rogers, L. (2020). Asymmetry of Motor Behavior and Sensory Perception: Which Comes First? Symmetrie, 12(5), 690.
Abstract: By examining the development of lateralization in the sensory and motor systems of the human fetus and chick embryo, this paper debates which lateralized functions develop first and what interactions may occur between the different sensory and motor systems during development. It also discusses some known influences of inputs from the environment on the development of lateralization, particularly the effects of light exposure on the development of visual and motor lateralization in chicks. The effects of light on the human fetus are related in this context. Using the chick embryo as a model to elucidate the genetic and environmental factors involved in development of lateralization, some understanding has been gained about how these lateralized functions emerge. At the same time, the value of carrying out much more research on the development of the various types of lateralization has become apparent.
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Rørvang, M. V., Nielsen, B. L., & McLean, A. N. (2020). Sensory Abilities of Horses and Their Importance for Equitation Science. Frontiers in Veterinary Science, 7, 633.
Abstract: Vision, hearing, olfaction, taste, and touch comprise the sensory modalities of most vertebrates. With these senses, the animal receives information about its environment. How this information is organized, interpreted, and experienced is known as perception. The study of the sensory abilities of animals and their implications for behavior is central not only to ethology but also to animal welfare. Sensory ability, perception, and behavior are closely linked. Horses and humans share the five most common sensory modalities, however, their ranges and capacities differ, so that horses are unlikely to perceive their surroundings in a similar manner to humans. Understanding equine perceptual abilities and their differences is important when horses and human interact, as these abilities are pivotal for the response of the horse to any changes in its surroundings. This review aims to provide an overview of the current knowledge on the sensory abilities of horses. The information is discussed within an evolutionary context and also includes a practical perspective, outlining potential ways to mitigate risks of injuries and enhance positive horse-human interactions. The equine sensory apparatus includes panoramic visual capacities with acuities similar to those of red-green color-blind humans as well as aural abilities that, in some respects exceed human hearing and a highly developed sense of smell, all of which influence how horses react in various situations. Equine sensitivity to touch has been studied surprisingly sparingly despite tactile stimulation being the major interface of horse training. We discuss the potential use of sensory enrichment/positive sensory stimulation to improve the welfare of horses in various situations e.g. using odors, touch or sound to enrich the environment or to appease horses. In addition, equine perception is affected by factors such as breed, individuality, age, and in some cases even color, emphasizing that different horses may need different types of management. Understanding the sensory abilities of horses is central to the emerging discipline of equitation science, which comprises the gamut of horse-human interactions. Therefore, sensory abilities continue to warrant scientific focus, with more research to enable us to understand different horses and their various needs.
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Scopa, C., Greco, A., Contalbrigo, L., Fratini, E., Lanatà, A., Scilingo, E. P., et al. (2020). Inside the Interaction: Contact With Familiar Humans Modulates Heart Rate Variability in Horses. Frontiers in Veterinary Science, 7, 998.
Abstract: A human-animal relationship can be developed through subsequent interactions, affected by the positive or negative emotional valence of the proceeding one. Horses implement a process of categorization to classify humans with whom they interact as positive, negative, or neutral stimuli by evaluating the kind of approach and the nature of the contact. In these terms, human-animal interactions are emotionally charged events, eliciting specific emotional states in both subjects involved. Although the human-horse relationship has been mainly investigated through behavioral analysis, physiological indicators are needed for a more objective assessment of the emotional responses. Heart rate variability (HRV) is a commonly used autonomic nervous system (ANS) correlate estimating the sympathovagal balance as a psychophysiological marker of emotion regulation in horses. We have assumed that long-term positive relationships with humans may have a positive and immediate impact on the emotional arousal of the horse, detectable, via ANS activity, during the interaction. We analyzed horses' heartbeat dynamics during their interaction with either familiar or unfamiliar handlers, applying a standardized experimental protocol consisting of three different conditions shifting from the absence of interaction to physical contact. The ANS signals were monitored through an innovative non-invasive wearable system, not interfering with the unconscious emotional response of the animal. We demonstrated that horses appeared to feel more relaxed while physically interacting (e.g., grooming on the right side) with some familiar handlers compared to the same task performed by someone unfamiliar. The shift of the sympathovagal balance toward a vagal predominance suggests that the horses experienced a decrease in stress response as a function not only of the handler's familiarity but also of the type of interaction they are experiencing. These results constitute the objective evidence of horses' capacity to individually recognize a familiar person, adding the crucial role of familiarity with the handler as a paramount component of human-animal interaction. Our rigorous methodological approach may provide a significant contribution to various fields such as animal welfare while further investigating the emotional side of the human-animal relationships.
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Trösch, M., Pellon, S., Cuzol, F., Parias, C., Nowak, R., Calandreau, L., et al. (2020). Horses feel emotions when they watch positive and negative horse-human interactions in a video and transpose what they saw to real life. Anim. Cogn., 23(4), 643–653.
Abstract: Animals can indirectly gather meaningful information about other individuals by eavesdropping on their third-party interactions. In particular, eavesdropping can be used to indirectly attribute a negative or positive valence to an individual and to adjust one's future behavior towards that individual. Few studies have focused on this ability in nonhuman animals, especially in nonprimate species. Here, we investigated this ability for the first time in domestic horses (Equus caballus) by projecting videos of positive and negative interactions between an unknown human experimenter (a “positive” experimenter or a “negative” experimenter) and an actor horse. The horses reacted emotionally while watching the videos, expressing behavioral (facial expressions and contact-seeking behavior) and physiological (heart rate) cues of positive emotions while watching the positive video and of negative emotions while watching the negative video. This result shows that the horses perceived the content of the videos and suggests an emotional contagion between the actor horse and the subjects. After the videos were projected, the horses took a choice test, facing the positive and negative experimenters in real life. The horses successfully used the interactions seen in the videos to discriminate between the experimenters. They touched the negative experimenter significantly more, which seems counterintuitive but can be interpreted as an appeasement attempt, based on the existing literature. This result suggests that horses can indirectly attribute a valence to a human experimenter by eavesdropping on a previous third-party interaction with a conspecific.
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