Cranial thoracic myelopathies (T1-T6 vertebrae): Retrospective evaluation of the signalment, clinical presentation, and, presumptive or final diagnoses in 84 dogs

Abstract

The aim of the study was to describe the signalment, clinical presentation and presumptive or final diagnoses of dogs with cranial thoracic spinal cord lesions identified on advanced imaging. Retrospective evaluation of the databases of three veterinary specialty centres, between 2009 and 2021, was performed to identify dogs with a lesion affecting the cranial thoracic vertebral column (T1-T6 vertebrae) as the primary cause for presenting signs of myelopathy and/or spinal pain. Eighty-four dogs were included in the study, with the majority (n = 76) presenting with a progressive history of over 4-weeks' duration. On neurologic examination, most dogs were ambulatory (n = 64), and the most common neuroanatomic localisation was the T3-L3 spinal cord segments (n = 63). Twelve dogs (14%) showed a short-strided thoracic limb gait on clinical examination. The most common diagnosis was neoplasia (n = 33), followed by anomalies (n = 22, including vertebral body malformations in 14 dogs) and degenerative disorders (n = 16, with intervertebral disc protrusion diagnosed in 9 dogs). The most common vertebrae affected were T3 and T5. Most dogs with degenerative conditions showed asymmetric clinical signs, and the majority of dogs with neoplasia showed signs of spinal hyperaesthesia on examination. The findings of this study describe the clinical signs and presumptive or final diagnoses associated with lesions affecting the cranial thoracic spinal cord. When combined with the signalment and clinical history, this information can assist in both the recognition of and problem-based approach to these cases.

Keywords: advanced imaging; ataxia; canine; neoplasia; neurological; spinal cord; two-engine gait.

Figure 1

MRI of case #72. Sagittal T1-weighed post-contrast image of the caudal cervical and cranial thoracic vertebral column (A) transverse T2-weighted (B) and transverse T1-weighted post-contrast (C) images at the level of T1-T2. A large, irregular and well-defined mass lesion involving the dorsal spinous processes of T1-T4 vertebrae is shown (red arrow). This mass is markedly heterogeneous on T2-weighted images (B) and shows marked enhancement in T1-weighted images after intravenous administration of gadolinium-based contrast agent (A,C). The mass showed extradural extension causing moderate spinal cord compression (star). The white arrowhead indicates the position of the spinal cord. On post-mortem examination, this mass was classified as a chondroblastic osteosarcoma.

Figure 2

MRI of case #34. Sagittal T2-weighed image of the cranial thoracic vertebral column (A); transverse T2-weighted image at the level of T2-T3 (B). At this level (T2-T3), there is an intervertebral disc protrusion which resulted in moderate ventral spinal cord compression (red arrow). Additionally, there is apparent bilateral vertebral articular process hypertrophy, causing mild bilateral dorsolateral spinal cord compression (stars). This was confirmed upon surgical decompression (T2-T3 hemilaminectomy).

Figure 3

Lesion location if a single vertebral body is considered.

Figure 4

Lesion location if a block of two vertebrae and their intervertebral disc space is considered.