Not long ago we spent a TidBit Tuesday discussing spinal arachnoid diverticuli (called SAD) in dogs. An article in The Journal of Veterinary Internal Medicine was recently published (2025:39.e17294) addressing this heterogenous disease in cats and I thought this might make for an interesting discussion. Read on if you’d like to learn more!
What is SAD?
Spinal arachnoid diverticuli (SAD) are caused by focal dilations in the subarachnoid space which often cause progressive neurologic signs. In dogs, it may be caused by an injury or be diagnosed as a primary finding. The etiology is unknown in cats because it is such a rare finding. The authors reported that 48% of the cats in the recent study did not have an underlying or previous spinal condition, suggesting primary SAD might be possible. This is in contrast to previous case reports in which all cats were reported to have SAD after a spinal condition. Perhaps this represents a congenital cause or perhaps we simply couldn’t identify the underlying cause.
What are common clinical signs and lesion localization?
Like dogs, thoracolumbar lesion localization was most common (86%) with a C1-C5 myelopathy less common (14%). Clinical signs reflect the lesion localization therefore most cats demonstrate paraparesis and proprioceptive ataxia. However, interestingly one cat (with a C1 SAD) demonstrated bilateral vestibular signs and proprioceptive ataxia. Although rare, vestibular signs with a high cervical lesion can occur and are suspected to result from disruption of the cervicospinovestibular tracts.
Fecal incontinence is common in dogs with SAD. This was rare in cats (1 cat) in this study and may relate to the anatomic location of the SAD (more thoracic than lumbar) or different sensory pathways to the external sphincter in the cat compared to the dog (we strongly suspect this in cats!).
How is SAD treated?
Treatment involves either medical or surgical management. Surgical management was undertaken in 8 of 20 cats (40%) and of those, 6 cats improved, 1 cat remained static and 1 cat deteriorated in the short-term follow up. Follow up of more than 6 months from surgery was considered long-term follow-up and this revealed 2 cats improved, 4 cats had deteriorated; the remainder did not have long-term follow-up data. In the 12 cats managed medically, 3 cats improved, 4 remained static and 5 deteriorated in the short-term follow-up. Data for only 5 cats was available for long-term follow-up. Four of the cats had deteriorated and 1 cat remained static. Although cats with surgical intervention appeared to improve in the short term, recurrence of signs or eventual deterioration was frequent in the cats managed surgically. The authors note that overall (regardless of treatment modality) 75% of cats worsened with time. This is similar to dogs; however, surgical outcome might be slightly better.
As you probably guessed, SAD is diagnosed with MRI. If you think you have a cat with SAD, please reach out to get a neurology consult so we can get them in the magnet for imaging!
I hope you enjoyed this article and look forward to working with you soon! I hope that those of you celebrating Easter had a peaceful, enjoyable celebration. Similarly, I hope that those of you celebrating Passover had 8 days of family and good remembrance. Most importantly, I hope that you (like me) are back to full carbs again!!