A Pressure Algometer Is a Useful Tool to Objectively Monitor the Effect of Diagnostic Palpation by a Physiotherapist in Warmblood Horses

There is a lack of scientific evidence for objective evaluation of neck and back musculoskeletal sensitivity in horses, although pressure algometry has been described as an objective tool to quantify musculoskeletal responses by mechanical nociceptive threshold (MNT) values. This study aimed to evaluate the use of pressure algometry for objectively quantifying the effect of diagnostic palpation applied by physiotherapists on the musculoskeletal function of the equine neck and back. The inter-examiner repeatability of animal physiotherapists was tested, and their subjective clinical scores for the vertebral column area were objectively compared with MNT values measured at the same locations to investigate the potential clinical implementation of the pressure algometer in daily equine rehabilitation practice. Six adult Dutch Warmblood riding school mares were randomly assigned to an experimental or a control group. The MNT of all horses was measured on 35 predefined sites on the vertebral column in the morning and in the evening of the same day. In the experimental group (n = 3), neck and back surface “temperature”, “pain”, “muscle tone”, and passive “mobility” were scored through palpation by three certified physiotherapists and related to MNT measurements at the same vertebral column locations. Agreement between the physiotherapists was determined from Spearman's rank correlation coefficients (P < .05). These correlation coefficients showed a significant agreement between the scores of individual physiotherapists and with objective MNT measurements. The three physiotherapists agreed best in their subjective gradings of “pain”, but less for “temperature” and “muscle tone”, and least for “mobility”. There was also a significant difference in MNT between individual horses. The physiotherapeutic diagnostic intervention did not significantly alter the MNT of the experimental group compared with the control group. There was a significant difference, however, between morning (7.4 kg/cm²) and evening (6.9 kg/cm²) MNT-measurements within the combined group (n = 6, P < .05). In conclusion, a pressure algometer proved to be a useful tool to objectively monitor the palpation of individual Warmbloods by individual physiotherapists. The correlation of their scores to the objective MNT measurements elucidated that there were differences on which scale (“pain”, “temperature”, “muscle tone”, “mobility”) they merely relied upon in their palpation. Significant effects of physiotherapeutic diagnostic palpation on MNT, however, were not found. The lower MNT of the horses at the second trial in the evening could be a sensitization of the measurement location because of bruising, a learning effect of the horses, or a diurnal fluctuation. The use of pressure algometry has both a potential to quantify clinical neck and back musculoskeletal sensitivity in horses possibly leading to dysfunction, as well as to objectively evaluate treatment results. Repeated measurements on the same day and on the same location along the vertebral column may influence absolute MNT values. The algometer can be used with success provided that the operator has proper and frequent training.