Scratchings-and-Sniffings

Posted by Animals at 5:11 PM Tuesday, October 20, 2009

Scratchings-and-Sniffings

More on Degenerative Myelopathy from Chai's Human

Posted: 20 Oct 2009 04:56 AM PDT

Miles-and-DrLarry-relax Pam, Chai's way cool human pal, wrote me a nice note on the post we did last week on degenerative myelopathy. I also got a comment from another reader that has a really nice blog on how she and her Great Dane are dealing with this issue.

Pam's note had a word of caution about the use of myelography as a diagnostic tool. Her issue is that myelography may result in complications for some dogs with DM. She has heard of dogs getting worse after the procedure. I've been looking into this and I have come across a few cautionary notes.
 
First of all, myelography is done primarily to rule out other disease that may look like DM. Inter-vertebral disc disease, where spinal disc material is impinging on the spinal cord can cause many of the same symptoms seen with DM. 
Myelography can be pretty invasive, too. The procedure calls for a contrast medium to be injected into the sub arachnoid space. The sub arachnoid space is a fluid filled cavity that surrounds the spinal cord and spinal nerve roots. The contrast medium outlines the spinal cord and nerve roots and can point to any abnormalities that might not be visible on a plane old x-ray.
 
Generally myelography is a safe and effective diagnostic procedure however there can be complications as with any invasive diagnostic technique. Boxer-with-DM
 
Since DM results in stripping away the myelin that insulates the nerve fibers, or axons, you can imagine why injecting anything into this area might result in greater inflammation and a worsening of the clinical signs.
 
An increase in spinal cord inflammation is one of the possible complications associated with any myelography procedure. This could be why some DM dogs don't react well to this procedure.
 
It would seem to me that there are other diagnostic tests that could rule out something like a space occupying tumor of the spinal cord or an inter-vertebral disc rupture. An MRI, for instance, would be a less invasive way to rule out these other conditions.
 
It's a good heads up from Pam, anyway. I'd sure discuss the diagnostic options with my veterinarian if DM is a possibility. MRIs are available in most areas these days. It may cost more to do an MRI compared to a myelogram, but I doubt if someone like Pam would care much about that.   

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