The Effect of Pulsed Electromagnetic Fields on Back Pain in Polo Ponies Evaluated by Pressure Algometry and Flexion Testing—A Randomized, Double-blind, Placebo-controlled Trial

This study assessed the therapeutic effect of pulsed electromagnetic fields (PEMF) on the backs of Polo ponies by measuring mechanical nociceptive thresholds (MNTs) and induced back movement. Twenty Polo ponies in regular training and competition were assigned to two groups. A double-blind, placebo-controlled, crossover field study with PEMF was performed, consisting of two 10-day therapy periods. At the beginning and end of each therapy period, the MNTs from 25 sites of the horses backs were assessed by pressure algometry (PA), and induced back movement was evaluated by flexion testing. Baseline MNTs were generally low, with means between 6.4 and 10.0 kg/cm2. Significant changes in MNTs occurred nearly equally after both the PEMF and the placebo control treatments (at 5 of 25 or 6 of 25 sites, respectively) and without any regular pattern. Changes were evident, predominantly as decreased MNTs within and between treatment periods. Flexion testing revealed stiffness or avoidance in 19 of 20 horses. Results of the flexion testing showed an increased number of physiologic reactions at the end of both treatment periods compared with baseline values. The effect of PEMF on back pain and range of induced back movement could not be proven in this study. Although pretherapy values indicated the horses might have experienced back pain, all horses were still actively used in sport, and back pain might not have been severe enough to allow a significant effect to be demonstrated.