CT-Scan Based Evaluation of Dorsal-to-Ventral Ratios of Paraspinal Musculature in Chondrodystrophic and Non-chondrodystrophic Dogs

Abstract

Objective: To assess and objectively quantify, with CT-scan exams, differences in cervical paraspinal musculature and vertebrae angulation that might influence the different predisposed sites for intervertebral disk disease observed in chondrodystrophic and non-chondrodystrophic breeds. Sample: Retrospective evaluation and analysis of cervical spine CT-scans performed on 30 dogs presented for clinical reasons unrelated to a cervical disk problem. 15 chondrodystrophic (Dachshunds) and 15 non-chondrodystrophic dogs (Labrador Retrievers) were included. Procedures: Height measurements of dorsal and ventral paraspinal musculature were performed on sagittal CT-scan reconstructions to generate dorsal-to-ventral height ratios. Additionally, disk angulation to the floor of the vertebral canal was determined for each cervical disk. On transverse plane images the areas of the dorsal and the ventral paraspinal musculature were measured and ratios calculated. Furthermore, estimations of moments exerted on the disk were evaluated through calculation of a dorsal-to-ventral ratio of moments applied at the level of each disk. Results: Dachshunds showed a relatively more prominent dorsal paraspinal musculature than Labrador Retrievers with statistically significant higher dorsal-to-ventral height ratios at C3/C4, C4/C5, C7/T1 ( p = 0.034 * , p = 0,004 ** , p = 0.004 ** ) and a dorsal-to-ventral area ratio at C3/C4 ( p < 0.001 ** ). Regarding the disk angle to the spinal canal floor along the cervical spine, Labrador Retrievers had a less steep conformation compared to Dachshunds with a significant difference at C2/C3 ( p < 0.001 ** ). Relation of moments calculations revealed statistically significant differences at C2/C3 ( p = 0.021 * ). Conclusion and Clinical Relevance: Significant differences have been found in the cervical spine of chondrodystrophic and non-chondrodystrophic dogs, regarding paraspinal musculature height and area ratios along with ratio of moments and vertebrae angulation. These differences may affect the anatomical and biomechanical dorsal-to-ventral paraspinal muscle relationship and potentially influence the load on intervertebral disks, especially in the upper cervical spine. Our findings could play a role in understanding the development of intervertebral disk disease.

Comparison of Dorsal-to-Ventral Ratios of the Cervical Paraspinal Musculature in French Bulldogs With and Without Cervical Intervertebral Disk Disease and Two Other Breeds Based on CT Scan Measurements

“…Cervical paraspinal muscle volume and distribution differ between chondrodystrophic and non-chondrodystrophic breeds, especially regarding the height ratio and vertebral angulation, with the chondrodystrophic breed having the more prominent dorsal portion of the musculature and the steeper vertebral angulation than the non-chondrodystrophic breed in Hartmann et al's study (1). While those differences have been observed, the exact influence of this observation in developing IVD degeneration and IVDH remains unknown (1).…”

“…The computer program was used to calculate the values of these areas. Muscle groups of the paraspinal musculature were divided into dorsal and ventral, left Finally, the area ratio for each cervical segment was calculated by dividing drl by vrl (1). Mean area ratios of both the IVDH and BOAS groups were determined to evaluate statistically significant differences.…”

“…To the author's knowledge, no previous study has addressed the potential influence of the paraspinal cervical musculature conformation on IVD degeneration and consequent IVDH predisposition in FBs. The aims of this study were to investigate the morphometry of the cervical dorsal and ventral paraspinal musculature in FBs and to compare these results with those of a similar study involving dachshunds and Labrador retrievers (1) (1). Another aim was to analyze, within the FB population enrolled in the study, whether differences could be observed in dogs with IVDH compared to dogs without IVDH (2).…”

Data_Sheet_1.DOCX

“…All dogs were positioned in standardized ventral recumbency, with their front limbs extended caudally to achieve optimal visualization of the entire cervical spine. Hartmann et al positioned dogs in dorsal recumbency, with their legs extended cranially (1). CT scans were performed from the head to T2 using a 16-slice helical CT scanner (Aquilion R , Canon medical systems GmbH, Germany).…”

“…The measurement method was identical to the method described by Hartmann et al A height ratio and angle measurements in the sagittal plane and an area ratio, alongside a ratio of moments in the transversal plane, were measured (1). All measurements were performed in the vertical axis of each IVD space to estimate the possible impact of the paraspinal musculature on IVD degeneration and IVDH development (1). CT images were analyzed using the Horos Dicom Image Viewer (Horos DICOM Image Viewer Version 3.3.6, Horos TM , USA).…”