This might be the SADdest acronym ever.
Do you remember the layers of the meninges? No? The dura mater, arachnoid and pia mater layers compose the meninges. Unfortunately, Pug dogs are prone to the development of small pockets of fluid (previously termed cysts, now termed diverticula) in the arachnoid layer, affecting the subarachnoid space. What is so critical about the subarachnoid space, you ask? Cerebrospinal fluid! Disrupt that, and we’ve got an obstruction. (Subarachnoid diverticulum is abbreviated SAD in the literature. Ugh!) Obstruction = spinal cord compression and voila, abnormal neurologic signs.
Diverticula can form anywhere along the spinal cord and result in minor signs such as mild ataxia, or severe signs such as fecal or urine incontinence and paresis. Interestingly, many dogs develop UMN urine and fecal incontinence with SAD. These dogs have normal anal tone, normal bladder tone and will squat to urinate/defecate normally. However, they frequently wet the bed in recumbence, or drop feces while walking.
How do we diagnose SAD?
MRI is the standard imaging modality to make a diagnosis of SAD. However, a myelogram can still do a pretty decent job because the diverticula are in the subarachnoid space. This is the same place we inject the contrast media for a myelogram.
How can we manage clinical signs?
Surgical decompression has been advocated for Pug dogs for many years. Essentially, we open the meninges, tie the dura open, allow the cyst to drain and close them up. In my experience, dogs typically improve, but then often worsen again in the future. In other words, not curative. An recent article out of Germany looking at 25 pugs with SAD agreed with my clinical conclusion. (Alisauskaite N, Cizinauskas, S et al. JVIM. 2019: 33:1376-1383.) They found that about 80% of the pugs got better in the short term, and of those that improved about 85% of them worsened again at least 12 months after surgery.
Medical management with anti-inflammatory medications, physical rehabilitation and other supportive care is what I recommend for most patients and I think the study above supports that approach. If the pug continues to progress while on medical management, and the owners are aware of the risk of long-term risk of failure from surgery, surgical decompression can be considered.
Sadly (SADly?), Pugs are prone to many spinal cord issues and that may contribute to failure in this surgery.
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