Effects of osteopathic manual therapy on the autonomic and immune systems and the hypothalamus-pituitary-adrenal axis in the horse

Manual therapies, physiotherapy, and modalities are often used as a treatment and prophylactic method for preventing various injuries, as well as a rehabilitation tool in the post-operative, traumatic period for horses. Significant results have been achieved with these therapies: increased joint range of motion, tissue extensibility, and reduced pain and inflammation. This study evaluated the effect of osteopathic manual therapy (OMT) on the nervous and immune systems, as well as on the hypothalamus-pituitary-adrenal (HPA) axis. To assess changes in these systems, non-invasive biomarkers were chosen: the heart rate (HR), respiratory rate (RR), temperature (T), as well as objective measurements: blood serum cortisol (BSC) concentration and white blood cell (WBC) count. A total of 30 thoroughbred horses were randomly divided into an experimental group (n = 15) and a control group (n = 15). Blood samples and physiological indicator measurements such as HR, RR, T, BSC and WBC were taken before (p0), after (p1) and one hour after (p2) the OMT treatment for the experimental group. Analogical sequence was performed for the control group without OMT. A significant increase of BSC by 0.94 µg/dl after OMT suggest a direct influence on the HPA axis. Also, a substantial decrease of WBC by 0.57 × 109/l indicates the immune system’s response to the treatment. Moreover, an observed significant decrease in HR and RR shows that the autonomic nervous system was affected by activating the parasympathetic nervous system. Based on the results obtained, it is concluded that OMT has an effect on the HPA axis and on the nervous and immune systems.