Standing myelography in the horse using a nonionic contrast agent.

This research aims to establish the efficacy and safety of using non-toxic, nonionic contrast medium (iohexol) for standing myelography in horses, as a safer alternative to the previously used metrizamide which had serious complications.

Background of the Study

• The focus of this research is standing myelography – a procedure that involves the injection of a contrast medium into the subarachnoid space in the spinal cord to visualize abnormalities.
• Previously, a contrast medium called metrizamide was used for this procedure. However, it had severe complications which made it a risky option for horses.
• This led researchers to consider less-toxic nonionic contrast media that have been recently introduced and claimed to reduce the incidence of complications.

Objective and Methodology

• The main goal of the study was to determine whether standing myelography using a nonionic contrast medium can provide a diagnostic study and be safely performed in horses.
• The proposed contrast medium to be used was iohexol.
• The procedure was performed on eight horses and the outcomes observed for each.

Results of the Study

• Out of the eight horses, a diagnostically satisfactory myelogram was achieved in five horses.
• In one horse, the contrast only flowed up to the C6 level, and in two horses, the contrast medium did not reach the cervical subarachnoid space.
• The study concluded that, due to the difficulty in achieving good flow of the contrast medium in some horses, the procedure may be of limited utility.

Implications and Conclusions

• Despite the limited success, if puncture of the lumbosacral subarachnoid space can be achieved easily and quickly, standing myelography could be a valuable procedure.
• Particularly, it could be attempted in cases in which the economic value of the patient makes myelography under general anesthesia impractical.
• For patients that present for ataxia evaluation, it might be possible to perform a standing myelogram at the time of CSF sample collection from the lumbosacral space.