Relative heights of the withers and the tubera sacrale and angulation of the lumbar and pelvic regions in adult sportshorses with hindlimb proximal suspensory desmopathy, sacroiliac joint region pain and control horses

Introduction: In non-lame horses, the tubera sacrale (TS) are usually lower than or, less commonly, equal in height to the withers. Thoracolumbosacral, pelvic and hindlimb posture/conformation may be influenced by musculoskeletal pain, and development and function of epaxial, pelvic and abdominal muscles. Objectives: To determine the relative heights of the withers and TS and the pelvic and lumbar angles in horses with forelimb and hindlimb lameness. Methodology: Retrospective clinical study over 12 months. Horses (n=193) presented for lameness or poor performance with a conclusive diagnosis based on abolition of clinical signs by diagnostic anaesthesia and imaging were included. Polystyrene hemispheres were adhered to the withers, TS and tubera ischiadica (TI). Lateral photographs were acquired with each horse standing squarely, with the head and neck in a neutral position, the metatarsal regions vertical, aligned with the TI. Relative heights of the withers and TS were determined using ImageJ. A line from the TS to the TI relative to the horizontal defined the pelvic angle. A line from the TS tangential to the lumbar region relative to the horizontal defined the lumbar angle. Results: The withers height was ≥ TS in 138/193 (71.5%) horses; the withers were lower than the TS in 55/193 (28.5%) horses. Pelvic and lumbar angles ranged from 20.0-42.7° (mean 28.9°, SD 3.4°) and 6.3-18.7° (mean 12.2°, SD 2.3°), respectively. No association between measurements and injury groups was determined. Conclusions: Withers height was < TS in a larger proportion of lame horses compared with published data for non-lame horses.