Quantitative Survey Radiographic Evaluation of the Lumbosacral Spine of Normal Dogs and Dogs with Degenerative Lumbosacral Stenosis

Survey radiographic studies of the lumbosacral region for 93 normal dogs and for 26 dogs with confirmed degenerative lumbosacral stenosis were reviewed. Normal dogs were divided into 9 groups based on age and body weight. For normal dogs, increasing age and body weight were associated with a decreased ability to extend the lumbosacral joint and with increased incidence and severity of spondylosis. Transitional lumbosacral vertebrae and evidence of lumbosacral disc space collapse were very infrequent findings, and the pivot point for lumbosacral motion was consistently centered over the lumbosacral disc space. Relative to an age/weight matched sub-population of normal dogs, dogs with degenerative lumbosacral stenosis had similar mean normalized lumbosacral vertebral canal height, larger mean neutral lumbosacral angle, decreased extension of the lumbosacral joint, increased flexion of the lumbosacral joint, reduced lumbosacral range of motion, increased lumbosacral dynamic malalignment, higher incidence and severity of spondylosis, higher incidence of transitional vertebrae, and higher incidence of lumbosacral disc space collapse. A logistic model based strictly on radiographic parameters was able to discriminate normal from affected dogs with an overall accuracy rate of 86\%.