Dogs with congenital extrahepatic shunts and absent portal vasculature noted on computed tomographic angiography can successfully undergo surgical attenuation

Abstract Objective To evaluate the clinical outcomes of dogs with a single congenital extrahepatic portosystemic shunt (EHPSS), in which portal vein atresia (PVA) was considered a differential diagnosis based on CT angiography (CTA), and that underwent surgical exploration. Methods Medical records were retrospectively reviewed for dogs with a single congenital EHPSS and absent portal vein branches on CTA. Data collected included signalment, clinical signs, preoperative and postoperative clinicopathologic values, diagnostic imaging findings, surgical details, and short- and long-term postoperative follow-up information. Results 7 client-owned dogs diagnosed with congenital EHPSS and suspected portal vein atresia on CTA that underwent surgical exploration at the William R. Pritchard Veterinary Medical Teaching Hospital at the University of California-Davis from 2010 to 2022 were identified. Surgical attenuation of the EHPSS was successfully performed in 6 of 7 dogs. Intraoperative mesenteric portovenography (IOMP) and/or clinical indicators (eg, absence of visceral congestion) were used to determine suitability for attenuation. In 2 dogs, IOMP was performed, which revealed intrahepatic portal vasculature only after temporary EHPSS occlusion. Postoperative clinicopathologic values and clinical signs were favorable in all 6 dogs that underwent attenuation, with no long-term complications reported. The numeric scoring scale applied to CTA did not appear to influence intraoperative decision-making. Conclusions Surgical attenuation of EHPSS in dogs with absent portal branches on CTA may be associated with favorable long-term follow-up, when supported by intraoperative findings. Clinical Relevance These findings highlight the limitations of CTA alone in preoperative decision-making for these complex cases and support the use of dynamic evaluation, such as IOMP, in guiding treatment strategies.