Gait abnormalities caused by selective anesthesia of the suprascapular nerve in horses.

The study focuses on identifying the impact of selective anesthesia of the suprascapular nerve (SSN) on gait abnormalities in horses. The research shows that SSN anesthesia leads to gait abnormalities and scapulohumeral joint instability, supporting the understanding of the SSN’s role in maintaining shoulder joint stability.

Research Methodology

• The researchers used three adult horses that didn’t have any previous signs of lameness at a walk for the study.
• Each horse was anesthetized and their right SSN was surgically exposed in order to place a perineural catheter. The catheter would allow the delivery of 1 mL of 2% mepivacaine hydrochloride, an anesthetic.
• Six hours after the horses regained their consciousness from anesthesia, they were videotaped while walking. The recording was done twice, before and after the administration of mepivacaine.
• The recorded footage was then analyzed to identify and compare the proportion of abnormal steps pre and post-anesthesia of the SSN. Any step which showed a significant degree of instability at the scapulohumeral joint (displayed by the lateral displacement of the upper part of the humerus) was considered abnormal.

Research Findings

• The results revealed clear signs of gait dysfunction in all three horses after the perineural administration of the local anesthetic agent.
• Anesthesia of the SSN was found to be resulting in scapulohumeral joint instability, apparent by constant lateral shifting of the shoulder during the weight-bearing phase of walking.
• The horses also showcased an increased number of abnormal steps after SSN anesthesia compared to before, which was statistically significant for all three test subjects.

Conclusion

• The findings provide strong support for the suprascapular nerve’s vital role in maintaining stability in a horse’s shoulder joint.
• The study also suggests that dysfunction of the SSN can potentially lead to the development of a clinical condition known as “sweeny,” characterized by gait abnormalities.