Impingement of dorsal spinous processes and their effect on performance in the Thoroughbred Racehorse

Impinging dorsal spinous processes (DSPs) of the thoracolumbar vertebrae are a common cause of poor performance in horses, with Thoroughbred racehorses appearing to be over-represented. Over the past 50 years, numerous medical and surgical treatments have been proposed for treating impinging dorsal spinous processes but none of these report on objective performance levels following treatment. The aim of this thesis is to objectively evaluate the effect impinging dorsal spinous processes has on performance in racing Thoroughbreds and assess the effectiveness of desmotomy of the interspinous ligament (DISL) in improving performance in these animals. A thorough review of the literature was performed. Medical records of all Thoroughbred racehorses undergoing desmotomy of one or more interspinous ligaments at a referral equine hospital, between February 2015 and September 2016, were reviewed. Matched controls were assigned to these horses. The time to follow-up was at least 12 months. 159 Thoroughbred racehorses met the inclusion criteria. Horses undergoing desmotomy had significantly better improvement in racing performance than did matched controls. Eight horses developed unilateral neurogenic atrophy of epaxial musculature. DISL between impinging DSPs can improve the performance of racehorses experiencing from poor performance caused by pain resulting from the impinging processes. The knowledge of neuro-anatomy of the equine back is currently lacking compared to that of humans and companion animals. Further investigation into the branching, and course of these nerves is required at all segments in the thoracolumbar region.