EQUINE VETERINARY EDUCATION Equine vet. Educ. (2018) 30 (9) 477-485 doi: 10.1111/eve.12623


Review Article


Clinical progress in the diagnosis of thoracolumbar problems in horses


G. Burns, A. Dart and L. Jeffcott* Faculty of Veterinary Science, Research and Clinical Training Unit, University Teaching Hospital Camden, New South Wales, Australia. *Corresponding author email: leo.jeffcott@sydney.edu.au


Keywords: horse; thoracolumbar; pain; diagnosis; spine


Summary It is well known that a painful back can be responsible for loss of performance in horses. Veterinary examination of the sore back used to be limited to manual palpation with diagnosis confirmed empirically by response to treatment. Today, due to advances in imaging, there are multiple methods for evaluating the pathology of the horse’s thoracolumbar (TL) spine. Radiography, ultrasonography, nuclear scintigraphy, thermography and algometry all play a part in developing a better understanding of equine TL problems. Despite this progress, definitive diagnosis can still be problematic. There is a lack of objectivity in understanding the implications of the pathology detected and its effect on the horse. It is difficult to determine the degree of pain experienced by individual horses and how that interferes with their performance and welfare. This paper emphasises the importance of a systematic clinical examination to identify the presence of pain that can be supported by recognition of pathology using a range of diagnostic aids. These will also be reviewed to assist the clinician in understanding the tools available to evaluate a horse with a sore back.


Introduction


A review of thoracolumbar (TL) problems was published over thirty years ago (Jeffcott 1979a). At that time, diagnostic protocols and therapies were limited. Radiography of the horse’s spine was difficult to perform and ultrasonography in veterinary medicine was new and had not been applied to the horse’s back. Nuclear scintigraphy in horses had only recently been reported (Ueltschi 1977). Veterinarians relied on the use of manual palpation, range of motion (ROM) and response to treatment to evaluate and treat horses with back pain. In thirty years, significant advances have been made in


understanding the biomechanics and pathology affecting the equine TL spine. Despite this, diagnostic techniques remain in the hands of specialists and the implications of back pain are often confusing. There is a need for research to improve our understanding of TL pain in horses. The only standardised method to objectively assess the degree of TL pain experienced by the horse was reported by Haussler and Erb (2006a,b) using the algometer. This tool applies pressure via a small device and measures the horse’s response. Most veterinarians do not have an algometer or the training to use one and so rely on digital palpation. This results in a subjective assessment and affects the ability to objectively determine a response to treatment.


The establishment of practical and objective criteria to


quantify TL pain is required to aid the clinician in assessing a horse for back problems (Jeffcott 2010). We have increased our ability to recognise pathology in the horse’s TL spine with radiography, nuclear scintigraphy and other techniques, but these techniques are not readily available to the general


practitioner. However, it is possible for a veterinarian in the field to identify and assess a horse with TL pain and determine if further diagnostic evaluation is warranted. This review will highlight the literature currently available to


help practitioners develop a better understanding of equine TL pain and its effect on performance.


Back pain and functional anatomy


The functional anatomy of the horse’s back is a major consideration in the evaluation of equine TL pain. The accepted biomechanical representation of the equine back is the concept of the string and bow arrangement suggested originally by Barthez 1798 (Figs 1 and 2). The bow section is the TL spine and the epaxial muscles, including the longissimus dorsi and multifidus muscle, providing stability as well as locomotion. The muscles involved in tensing the bow are the hypaxial muscles that lie ventral to the transverse processes of the vertebrae: the psoas major and minor, the iliacus and the quadratus lumborum. The sternum, linea alba and the abdominal muscles, including the transverse abdominus, the rectus abdominus and the two oblique muscles make up the string of the bow (Slijper 1946) and are involved in flexing the back. The psoas muscles have also


Retractors of foreleg


Epaxial musculature of spine


477


Protractors of hindleg


Sternum and abdominal muscles


Protractors of foreleg


Abdominal viscera


Fig 1: Bow and string diagram of the biomechanics of the horse’s back (Jeffcott 1979a).


© 2016 EVJ Ltd


Retractors of hindleg


STRING


BOW

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