Ultrasonographic evaluation of the equine back

Abstract

For thoracolumbar disorders of the horse there are various causes: osseous lesions and soft tissue injuries, in particular strains of muscles and ligaments. The sonography, an established method in equine surgery to diagnose orthopedic problems of the distal limbs, enables the veterinarian to better investigate back pain caused by soft tissue injuries, which cannot be evaluated with radiography or scintigraphy properly. For determining reference values for better recognition and differentiation of pathological changes, we depicted and measured anatomical structures of the thoracolumbar region of the equine back. The sonographic examination included 22 Swiss Warmblood horses, which had an unremarkable history concerning back problems. We used the ultrasound system ACUSON 128 R/F® with a 5,0 MHz-linear- and a 3,5 MHz-sector-probe. Additionally panoramic images were produced by means of the SieScape mode of the system SONOLINE® Elegra from Siemens. The sonographic pictures were compared with anatomical transversal and longitudinal dissects. The skin, the subcutis, the thoracolumbar and subcutaneous fascia, the supraspinous ligament, the muscles and the dorsal contour of the spinous processes could be depicted well. Due to the different topography, the interspinal spaces and the interspinal ligaments were not satisfyingly demonstrable except in the cranial thoracic region. Sonography seems to be a useful diagnostic instrument to evaluate soft tissue injuries of the equine back, particularly lesions of the supraspinous ligament and the muscles. The findings need to be evaluated in conjunction with the results from other diagnostic methods, especially the clinical examination. For the evaluation of alterations in the interspinal spaces and of the small intervertebral joints, sonography is of minor value.