Kinematic study of back movement in clinically sound malinois dogs with consideration of the effect of radiographic changes in the lumbosacral junction

Objective - To determine thoracolumbar spinal movement in dogs and the influence of subclinical radiographic changes involving the lumbosacral junction. Study Design - Experimental study. Animals - Clinically sound Malinois dogs (n=22). Methods - Kinematic analysis of markers on the spinal processes of C7, T6, T13, L3, L7, and S3 was performed while dogs were walking on a treadmill. Range of motion (ROM) in the transverse and vertical direction and the time of occurrence (TOO) of the maximal marker position were calculated. ROM and TOO of angulations formed by the corresponding markers were calculated. Initial kinematic analysis was performed without knowledge of the radiographic changes, and then data were reanalyzed to determine whether vertebral changes influenced back motion. Based on the results of radiographic analysis of the lumbosacral junction, dogs were divided into 3 groups: 1=no radiographic changes; 2=shortened L7 vertebra; and 3=transitional vertebrae, spondylosis, subluxations, and spondylarthrosis of the lumbosacral junction. ROM and TOO were compared using ANOVA for repeated measures and a Bonferroni's post hoc test; P <.05 was considered significant. Results - The highest transverse ROM was achieved by markers T6, T13, and L3, and in the vertical direction by S3; however, there were no significant differences in ROM in horizontal angulations. In the sagittal plane, T13-L3-L7 had a lower angulation than L3-L7-S3. In Group 3, transverse ROM for C7 was significantly higher than in Group 1; the horizontal angular maximum of T13-L3-L7 occurred significantly earlier. Conclusions - Significant kinematic changes were detected between clinically sound dogs with radiographic lumbosacral changes and dogs with no radiographic abnormalities. Clinical Relevance - Kinematic data from clinically sound dogs can be used for comparison with data from dogs with gait disturbances associated with orthopedic or neurologic disease or changes associated with therapy. (c) Copyright 2007 by The American College of Veterinary Surgeons.