BACKGROUND: This study describes the ultrasonographic appearance of the atlanto-occipital space and ultrasound-guided collection of cerebrospinal fluid (CSF) in cattle. The atlanto-occipital space of 73 euthanized cattle (group A) and 14 live cattle with neurological disorders (group B) was examined in the sagittal and transverse planes using a 5.0-MHz convex transducer. Optimal ultrasonograms were frozen on the screen and various variables were measured in both planes using the electronic cursors. Puncture of the subarachnoid space was achieved using a spinal needle introduced in the median plane in a caudoventral direction while the spinal cord was viewed in longitudinal section. The examination of cerebrospinal fluid (CSF) was limited to gross evaluation and a red blood cell count.
RESULTS: The spinal cord and the subarachnoid space were seen in the sagittal plane in all cattle. In group A, the mean distance between the skin and subarachnoid space was 38.6 mm, the mean depth of the subarachnoid space dorsal and ventral to the spinal cord was 8.9 mm and 8.4 mm, respectively, the mean diameter of the spinal cord was 9.9 mm and the mean diameter of the dural sac was 26.9 mm. These measurements were similar on transverse images. For collection of CSF from the subarachnoid space, the spinal cord was viewed in longitudinal section. All CSF samples from group A were colourless and clear and the median erythrocyte count was 2.5/μl. Ultrasonographic findings and results of CSF analysis were similar in group B.
CONCLUSIONS: Ultrasonography is useful for the visualisation of the spinal cord and facilitates the safe collection of CSF from the atlanto-occipital space in cattle.