Sensory laterality, immune system and stress in horses (Equus caballus): Impact of transportation, social disruption, changes in housing conditions and initial training
In collaboration with Prof. Dr. Volker Stefanski, Behavioral Physiology of farm animals, University Hohenheim
This study aims to investigate whether, particularly, short term stress enhances sensory laterality, i.e. the preference for using the sensory organs of a particular side. We aim to evaluate whether sensory laterality goes along with changes in physiological indicators of stress. The relationship between sensory laterality, stress and immune functions is poorly studied in mammals and particularly in the horse. Here, we aim to investigate the mutual interrelation of these factors. Laterality of the brain hemispheres, i.e. the specialization of the hemispheres to dominantly control certain tasks, has been shown in many species and is expressed by motor and sensory laterality, i.e. the unilateral use of hands, paws, hooves or sensory organs. Motor laterality has been linked to individual cognitive biases. For example, left-handed animals tend to be more fearful and more reactive. Characteristics of sensory laterality have been linked with the emotional content of a particular situation. Many animals prefer to use the left eye, ear or nose/nostril when confronted with novel or negative stimuli, with a conspecific and with a person. During high emotionality left sensory organ use seems to be more pronounced. Emotional reactions to stressors can be analysed by measuring physiological and immunological parameters. Within seconds after a stressor, the sympatho-adrenal axis (SAM axis) produces epinephrine and norepinephrine and the hypothalamo-pituitary axis (HPA axis) secretes glucocorticoids. Both the SAM axis and the HPA axis influence the immune system. Changes in immune function can be measured by determining immune cells (granulocytes, monocytes,
CD4+ T cells, CD8+ T cells, B cells). We assume that short term stressors, such as transportation and social stressors, cause horses to increase left sensory organ use, cortisol and epinephrine / norepinephrine secretion as well as granulocyte numbers and immunoglobulin A in faces. Long-term stress caused by social instability, changes in housing conditions, and initial training may be reflected by increased motor laterality and faecal cortisol metabolites, reduced CD4+ T cells, CD8+ T cells and immunoglobulin A in faeces, and a shift from a Th1 to a Th2 dominated cytokin profile. These relationships shall be tested under condition of practical relevance with the goal to achieve information which is relevant to animal welfare and horse husbandry. Increased left sensory organ use may prove be a fast behavioural indicator for acute stress in horses.
Conservation and Transportation Methods for Glucocorticods and Immunoglobuline A from Faces and Saliva
The project aims in establishing conservation and transportation methods for an easy to handle ‘Sampling Kit for Stress in Horses’. Stress related diseases are a severe threat to horse trainers and keepers. To date stress hormone samples can be sent to laboratories only deep frozen. This remains to be a challenge for scientific work groups, vets and laypersons. The developed ‘Sampling Kit for Stress in Horses’ shall be sold in Europe and USA directly to labs, vest and laypersons. It will enable easy sample collection and submission of saliva and faecal samples to the lab of the scientists’, the vets’, as well as the horse owners’, trainers’, and keepers’ personal choice.
In the lab horse specific Enzymeimmunoassays (ELISA tests) will be used to analyze the robustness and validity of the conservation and transportation methods for Glucocorticoids and Immnuoglobulin A from horse saliva and faeces.
From August 2016 – January 2017 we will start testing different conservation and transportation methods. The applicability will be tested from February 2017 – January 2018 by analyzing samples of an experiment on several stress situation in horse management and handling.