Thoracolumbar hydrated nucleus pulposus extrusion and intervertebral disc extrusion in dogs: Comparison of clinical presentation and magnetic resonance imaging findings

• Published in: The veterinary journal (1997) 2024-08, Vol.306, p.106178, Article 106178
• Main Authors: Alcoverro, E., Schofield, I., Spinillo, S., Tauro, A., Ruggeri, M., Lowrie, M., Gomes, S.A.
• Format: Article
• Language: English
• Subjects: Disc herniation; Myelopathy; Neurology; Spinal cord; Veterinary
• ISSN: 1090-0233; 1532-2971; 1532-2971
• DOI: 10.1016/j.tvjl.2024.106178

Thoracolumbar hydrated nucleus pulposus extrusion (TL-HNPE) is an increasingly recognised pathology with a substantial lack of literature describing its features. The aim of this retrospective case-control study was to analyse the clinical and magnetic resonance imaging (MRI) features of dogs with TL-HNPE compared to dogs affected with thoracolumbar intervertebral disc extrusion (TL-IVDE). Data from dogs diagnosed with TL-HNPE and TL-IVDE via MRI at two referral hospitals, were retrospectively collected and compared in terms of clinical signs and MRI features. Cases diagnosed with TL-IVDE were deemed controls. The MRI features of the affected IVD space, herniated IVD material, affected overlying spinal cord and local epaxial musculature were evaluated for each group. Fifty-one cases with TL-HNPE and 105 randomly selected cases of TL-IVDE were included. Several signalment and neurological signs were identified as statistically distinct between groups in univariate analysis. Multivariate analysis identified that dogs affected with TL-HNPE were typically older, less likely to be chondrodystrophic (62.2 % vs. 91 %), more frequently experiencing a peracute onset (90.2 % vs. 61.9 %) often attributed to a suspected trauma linked with exercise (37.3 % vs. 10.5 %), being less frequently progressive (41.2 % vs. 86.5 %) and with herniated disc material less frequently lateralised (72.6 % vs. 89.5 %) than cases with TL-IVDE. MRI-identifiable intervertebral disc degeneration was found in every TL-IVDE case but only in 60 % of TL-HNPE cases. TL-HNPEs were associated to significantly less spinal cord compression and less hyperalgesia than TL-IVDE. •Dogs with TL-HNPE were significantly older than those with TL-IVDE.•The clinical signs in TL-HNPE were usually peracute to acute, associated to a trauma, exuberant exercise and vocalisation.•Most TL-HNPE occurred at the thoracolumbar area and caused less spinal cord compression and hyperaesthesia than TL-IVDE.•TL-HNPE were almost invariably hyperintense on T2-weighed and gradient echo sequences on magnetic resonance imaging.