Efficacy of the new radiographic measurement method for cervical vertebral instability in wobbling foals.

Cervical myelography and survey radiography was performed on 12 light breed wobbling foals and a new radiographic measurement method was applied for more accurate diagnosis of cervical vertebral instability. Ratios of stenosis of the spinal canal on survey radiography and myelography using relative values in an individual foal were defined on radiograms of lateral flexed position of mid-cervical region, and coincidence between the ratios and histopathological lesions in the cervical spinal cord was investigated. Five of 6 foals had ratios of stenosis on myelography more than 40% at the intervertebral sites where the most severe histopathological lesions were observed. Four of 6 foals had ratios of stenosis on survey radiography more than 40% at the intervertebral sites where the most severe histopathological lesions were observed. Four of 6 foals had ratios of stenosis on survey radiography more than 40% at the intervertebral sites where the most severe histopathological lesions were observed. False-positive diagnosis of CVI was observed in 1 out of 6 foals without histopathological lesion when both ratios of stenosis on myelography and survey radiography were applied. Although the standard value of 40% should be further investigated, the new radiographic measurement method in this study is very useful in clinical diagnosis of cervical vertebral instability in wobbling foals, and the presence of lesions in the cervical spinal cord and their sites by survey radiography may be estimated more accurately.