Portosystemic Shunts and Their Effect on the Nervous System
Portosystemic shunts (PSS) are common in small breed dogs and surgical correction is commonly recommended. However, there is concern about neurologic signs peri-operative for these patients. Some develop seizures, mentation changes, and other neurologic signs before shunt attenuation while others do not show signs until after shunt attenuation. Sadly, the presence of neurologic signs is a poor prognostic indicator according to many studies. One recent study looked for prognostic indicators in dogs that develop seizures post attenuation (PAS) within 7 days of surgery. I hope you'll find the study as interesting as I did!
Study Design
This was a retrospective study including 93 dogs from 14 different institutions. 53% of dogs received prophylactic levetiracetam. There were lots of different small breeds with a median age of 34 months (range 5-124 months).
Results
17.3% of the dogs had experienced at least 1 seizure prior to surgery.
Interestingly, 78% of the dogs had exhibited neurologic abnormalities including those with seizures.
Only 30% of dogs with PAS survived to 30 days. Yikes.
More often those with focal seizures survived, compared to dogs with generalized seizures.
Sadly, the most common reason for euthanasia following the shunt was the presence of uncontrolled seizures.
Key Points
According to their multivariate analysis the only two factors associated with short term survival were 1) having a history of seizures PRIOR to shunt correction (p=.004) and 2) the development of focal PAS (p=.0003). That's it!
So, what do we tell our clients? Well, for starters..they need to know that these pets are are risk of developing seizures even if they DON'T have surgery. But, according to this study if they do elect surgery, the development of generalized seizures is a poor prognostic indicator.
This article was packed with other data so if you want to read the entire thing please reach out and let me know.
Reference:
Mullins RA, Sanchez Villamil C, Selmic LE, et al. Prognostic factors for short term survival of dogs that experience post attenuation seizures after surgical correction of single congenital extrahepatic portosystemic shunts: 93 cases (2005-2018) Vet Surg.2020; 49:958-970.
That's it for now! I'm maintaining curbside service for the summer and am starting to widen my travel radius again. Please reach out if I can asist with a case. Stay safe, stay healthy!