In the course of doing more than 80 myelograms per year during the past five years, Barrie Grant, DVM, MS, Dipl. ACVS, has the procedure down to a science. Grant explained to veterinarians at the 2006 AAEP Convention how they can perform the valuable diagnostic procedure in less than 30 minutes.

A myelogram involves injecting a contrast agent, which is a solution that shows up on radiographs, into the spinal canal to reveal any compressive lesions of the spinal cord that could be affecting the horse’s neurologic function. Grant advocates using myelograms not only for horses with obvious neurological dysfunction (wobblers), but also horses who have poor performance characterized by stumbling, stiffness, weak backs, knuckling when stopping, offset tail carriage, and delayed limb placement.

“We feel it’s a very valuable diagnostic tool for us,” Grant said, adding that the procedure helps “turn neuro case lemons into lemonade.”

Grant emphasized that safety and teamwork are crucial to performing this procedure–he recommends having at least three people involved in controlling all aspects of anesthesia, positioning, and radiographs.

“It’s all about teamwork and keeping it simple,” he said.

Grant also explained the safety measures his team uses while performing myelograms, including reading the label of the radiographic contrast media (Grant uses iohexol) aloud by both the technician and the veterinarian while preparing to administer the solution. This is done because injecting the wrong kind of solution into an area so close to the brain can have fatal consequences.

Once the horse is anesthetized and its head is positioned on a ramp to keep the contrast media from flowing into the brain, Grant performs the spinal tap to inject the fluid.

“Try to guide it in like you’re shooting pool,” Grant said. “I try to really take my time while I’m doing it. Be as comfortable and relaxed as you can be.”

Grant says that if the tap produces bloody fluid, it’s best to be patient and wait it out a couple minutes, as many bleeds resolve on their own. He injects contrast media over three minutes, with an assistant counting down every 30 seconds.

Grant then proceeds with shooting cranial, caudal neutral, extended, caudal flexed, mid flexed, and skull radiographs. Films are processed immediately–while the horse is still down–to ensure that sufficient views and quality were achieved in the first set. Angles can be re-shot if necessary.

“Don’t just quit after (finding) the first lesion,” he said. “Many horses have multiple lesions, so you need to keep going.”

If the radiographs are sufficient, he allows the horse to recover from anesthesia.

Grant estimated a well-practiced team can perform the entire procedure in under 30 minutes. This technique gives veterinarians another way to detect causes of illness in some of the most difficult neurologic cases.

Get research and health news from the American Association of Equine Practitioners 2006 Convention in The Horse’s AAEP 2006 Wrap-Up sponsored by OCD Equine. Files are available as free PDF downloads