Prospective Study Comparing Outcome following Complete Polypropylene Suture Ligation versus Partial Thin Film Band Attenuation of Congenital Portosystemic Shunts in Dogs

SIMPLE SUMMARY: A congenital portosystemic shunt is an abnormal vessel that bypasses the liver. Dogs born with this shunt may display various clinical signs due to substances that are usually metabolized by the liver being present in much higher levels in the bloodstream. Surgery to narrow or close the shunt is recommended. Materials placed to narrow the shunt aim to close the shunt fully over time by creating an inflammatory reaction around the shunt, although some dogs may also receive a second surgery if this is not successful. Multiple acquired shunts may also develop following the narrowing or closure of a congenital shunt; these represent the opening of previously non-functional vessels to relieve increased pressure within the liver. The main objective of this study was to report the outcome for dogs treated with a ‘complete ligation where possible’ philosophy. The second aim was to compare the outcome between complete polypropylene suture ligation and partial thin film band narrowing of the congenital extrahepatic portosystemic shunt in dogs. Dogs that could not tolerate acute complete shunt ligation at surgery received partial shunt narrowing with a thin film band. Of the 110 dogs enrolled, 57 received complete ligation and 53 received partial thin film band narrowing of the shunt. Peri-operative mortality, the occurrence of post-attenuation neurological complications, the occurrence of multiple acquired shunts, the postoperative clinical shunt score and quality of life score was not significantly different between the two groups. ABSTRACT: The main objective was to conduct a prospective study reporting the outcome for dogs with an extrahepatic congenital portosystemic shunt (CPSS) treated with a ‘complete ligation where possible’ philosophy. The second aim was to compare the outcomes following complete (C) polypropylene suture ligation versus partial thin film band (TFB) attenuation of a CPSS in dogs. Dogs that could not tolerate acute complete shunt ligation at surgery received partial shunt attenuation with TFB. Peri-operative complications, mortality, follow-up imaging findings, pre- and post-operative bile acid stimulation test results and details of any revision surgery performed were recorded. A follow-up health-related quality of life questionnaire enabled the calculation of a postoperative clinical shunt score, a quality of life score, and determined if any dogs were still on a hepatic diet and/or other medical management at a minimum of 6 months after surgery. Of the 110 dogs enrolled, 57 received complete ligation and 53 received partial TFB attenuation. Peri-operative mortality, the occurrence of post-attenuation neurological complications, the occurrence of multiple acquired shunts, the postoperative clinical shunt score and quality of life score were not significantly different between the two groups. Dogs in the C group were older, heavier and demonstrated a greater number of shunt classifications where the entry into the systemic circulation was the phrenic vein or azygous vein. Dogs in the TFB group had a greater number of unchanged bile acid concentrations after surgery, were more likely to remain on the hepatic diet and/or medical management after surgery and underwent a greater number of revision surgeries. There was variability in the precision of both ultrasound and computed tomographic angiography follow-up imaging compared to intra-operative mesenteric portovenography findings at revision surgery. Overall, dogs with an extrahepatic portosystemic shunt receiving either complete acute shunt ligation or partial TFB shunt attenuation are expected to have an excellent long-term clinical outcome and there is no reason to suggest that a dog able to tolerate complete acute shunt closure should be denied the benefit of this.