Thoroughbred horse 2 years of age Male intact Presented with moderate ataxia and hypermetria, already present when walking. Radiographs of the neck were taken. Radiographic examination Laterolateral view of the cervical spine: Top left C1 and C2, top right C3- C4, low left C5-C6 Radiographic finding and diagnosis
- There is malalignment of the C3-4 cervical vertebrae with dorsal tipping of the cranial part of the body of C4 (arrow) and mild step formation of the vertebral canal.
- The spinal canal at the level of C4 is wedge shaped and narrowed cranially (arrowheads).
- The synovial joints between C6-7 are moderately enlarged, with an irregular surface and narrowing of the intervertebral foramina (small arrow).
Radiographic finding and diagnosis The radiological diagnosis was stenosis of the spinal canal with malalignment C3-4, compatible with cervical stenotic myelopathy. Moderate osteoarthritis of the synovial joint C6-7. Comments
- To better assess the degree of the spinal cord compression, a myelography would have been necessary, with radiographs taken in neutral position and with flexion of the neck. However, in combination with the clinical presentation, the radiographic study was considered diagnostic.
- To better assess the degree of osteoarthritis of the synovial joints C6-7, oblique views may be helpful. The superimposition of the bony structures on the lateral view may lead to misinterpretation.
- Considering the very young age of the horse and poor prognosis the owner declined further investigation and elected euthanasia.
- Cervical stenotic myelopathy (or Wobbler syndrome) results in compression of the spinal cord by malformed cervical vertebrae.
- Spinal cord compression can be dynamic or static.
- Dynamic compression results from vertebral instability and produces intermittent spinal cord compression during ventroflexion of the neck, compression is relieved when the neck is in neutral position.
- Static compression is continuous spinal cord impingement regardeless of cervical position.
- In older horses, the ataxia may compare at more 10 years of age primary resulting from osteoarthritic enlargement of the caudal cervical articular facets, with or without some degree of vertebral instability. In these cases, affected horses appear neurologically nomal until osteoarthritic enlargement of the articular facets impinges on the cervical spinal cord.
- In the literature, data on the absolute minimum sagittal diameter of the intervetebral canal have been recorded, as well as the intravertebral minimum sagittal diameter ratios in adult horse between for C4-C7.
- One of the most recent paper assess the utility of the inter- and intravertebral minimum sagittal diameter ratios in the diagnosis of cervical vertebral malformation, measured as shown:
From Hahn et al, Vet Rad & US 2008, 49, 1, pp 1-6
