Relationships between radiography of cervical vertebrae and histopathology of the cervical cord in wobbling 19 foals.

Nineteen wobbling foals (17 males and 2 females) showing lameness of hindlimbs at 6 to 21 months of age were investigated radiographically and histopathologically. Minimum sagittal diameter (MSD), minimum flexion diameter (MFD) and minimum dural sagittal diameter (MDD) were measured on plain radiograms or myelograms taken at neutral and flexed positions as indicators of narrowed vertebral canal. After necropsy, the cervical spines and the spinal cord were examined macroscopically and respectively the relationships between radiographic findings and the corresponding morphological lesions were evaluated. Radiographically, lower values than each minimum reference limits were recorded in 14 foals in MSD, 5 foals in MFD and 6 foals in MDD, respectively. According to the histopathologic examination, the disappearance of axons and myelin sheaths, vacuolated spongy degeneration and appearance of macrophages were recognized symmetrically in the white matter of the cervical cord. These lesions were centrally located at the spinal cord radiographically demonstrated as compressed sites in 12 out of 17 foals examined. Macroscopically, asymmetrical overgrowth of one side of the process, encroachment of articular processes into the intervertebral foramina and proliferation of bone around articular facets were observed in the articular processes of bone specimens in the caudal neck of 6 foals. In conclusion, the equine incoordination might mainly be caused by the cervical stenotic myelopathy resulting from cervical vertebral malformation, and therefore the cervical vertebral radiography, especially myelography, is quite very important and effective for the diagnosis of wobbling foals.