Cain B, Jones JC, Childs K.
Introduction/Purpose: Belgian Malinois are one of the most popular breeds used as military working dogs. Their work requires repetitive physical activities that place strain on their lower back region and may lead to lower back pain. However their stoicism and high drive may also cause them to mask their lower back pain, continue to work, and cause additional back injury. Quantitative indicators of back pain would be helpful for use in evidence-based studies on the effectiveness of early therapeutic interventions in these dogs. Previous studies in humans have reported an association between decreased paraspinal muscle mass and lower back pains. It is our hypothesis that muscle mass may also be a quantitative indicator of low back pain in working Belgian Malinois.
Methods: Computed tomography (CT) databases from the Department of Defense Military Working Dog Veterinary Service were searched for Belgian Malinois that had scans of the lumbosacral region. Digital CT images were uploaded directly to an image analysis workstation. Hard copy CT images were converted to DICOM format using a digital scanner system (Vidar Sierra Advantage, Sound Eklin, Carlsbad, CAl and then transferred to the image analysis workstation. All images were analyzed using the same software (Osirix version 4.1.2). Centimeter scales were used for calibration of area measurements in hard copy images. A single observer unaware of clinical status traced triplicate regions of interest (ROls) around multifidus, psoas, quadratus, longissimus, and serratus dorsalis lateralis muscles where visible at the L5-6, L6-7, L7- S1, and S1-2 vertebral levels. Regions of interest were also traced around vertebral bodies at the same locations as muscle ROI’s and used to calculate muscle/vertebral body area ratios. After all CT measurements were recorded, medical record data were reviewed and dogs were divided into two groups: dogs with lumbosacral pain and dogs without lumbosacral pain. Mean CT area ratios for each muscle were calculated for each dog group and compared between groups.
Results: Nine digital and 8 hard copy CT studies were included in analyses. Of the 17 Belgian Malinois included in the study, 13 were males and 4 were females. Twelve dogs were in the lumbosacral pain positive group, and 5 dogs were in the lumbosacral pain negative group. All paraspinal muscle groups in dogs with lumbosacral pain had graphically lower mean area ratios, except the quadratus lumborum, which was higher by 0.06.
Discussion/Conclusion: Findings were consistent with previous human studies and supported the theory that decreased paraspinal muscle mass may be a quantitative indicator of lower back pain in working Belgian Malinois. Future studies are needed to determine the effect of therapeutic interventions on paraspinal muscle mass in dogs with lower back pain.