The effects of upper cervical spine manipulation on spot tenderness within the erector spinae muscles of show-jumping horses

Purpose: Trigger points may occur when muscle is subject to direct trauma, sustained tension, fatigue, radiculopathy, joint dysfunction and emotional stress, which may cause aberrant nerve conduction and dysfunction of the motor neurons. Any of these factors may increase the possibility of overload stress to a muscle and may convert a latent trigger point to an active one. In humans, due to muscle attachments, spinal manipulation causes reflex relaxation of associated and distal musculature. The purpose of this study was to assess the effects of upper cervical spine manipulation, specifically C1, on pain tolerance of trigger points over the erector spinae muscles in show-jumping horses. Method: This study consisted of two groups, the experimental and the control group, each consisting of ten horses. Potential candidates were examined and accepted based on the inclusion and exclusion criteria. The only method of treatment that was administered to each horse was chiropractic manipulation to the most restricted side of the UPPER CERVICAL SPINE joint complex, from which the objective findings were based. Procedure: Both groups were examined for trigger points within the Erector Spinae muscles and these trigger points were assessed, via an algometer, for spot tenderness. All horses were then examined for a cervical restriction of the upper cervical spine. Only the experiment group had the restriction corrected by a chiropractic manipulation and thereafter both groups were reassessed two minutes later, and then again two weeks later, via an algometer, for spot tenderness within the same trigger points. Results: Statistically significant changes were found when comparing the algometer readings before the adjustment with the algometer readings after the adjustment on the right. Otherwise no statistically significant differences were found when comparing algometer readings before the adjustment with the algometer readings after the adjustment on the left, or when comparing the algometer readings before the adjustment with the algometer reading two weeks later bilaterally. Conclusion: The results were inconclusive with regards to immediate and prolonged effects of upper cervical spine manipulation, specifically C1, on pain tolerances over the erector spinae muscle. As this study was directed to a small group of subjects, accurate conclusions cannot be formulated due to the insignificant findings obtained from the study and further research needs to be performed on the effects of upper cervical spine manipulation on trigger points in horses.Dr. Ashleigh Deall Dr. Alex Niven Dr. Chris Yelverto