Surgical Success in Dogs with Missing Portal Veins? This New Study Says Yes

Dogs with Congenital Extrahepatic Shunts and Absent Portal Vasculature Noted on Computed Tomographic Angiography Can Successfully Undergo Surgical Attenuation

Sohee Bae, William T. N. Culp, Allison L. Zwingenberger

Background

Congenital extrahepatic portosystemic shunts (EHPSS) in dogs are often evaluated using computed tomographic angiography (CTA). When portal vasculature is not visible, this raises concern for portal vein atresia (PVA), a rare condition previously considered a contraindication for shunt attenuation due to risk of severe portal hypertension. However, absent portal branches on CTA may also reflect secondary portal vein hypoplasia (sPVH), a potentially reversible condition. Distinguishing between these diagnoses is critical to determining surgical candidacy.

Methods

This retrospective case series reviewed medical records of 7 dogs diagnosed with EHPSS and absent portal vasculature on CTA who subsequently underwent surgical exploration at UC Davis between 2010 and 2022. Data collected included imaging findings, intraoperative observations, clinical outcomes, and follow-up. Some dogs underwent intraoperative mesenteric portovenography (IOMP) during temporary shunt occlusion to assess for hidden portal vasculature. Surgical attenuation was performed if intraoperative findings supported adequate portal vasculature.

Results

Of the 7 dogs that underwent surgery, 6 successfully received shunt attenuation using an ameroid ring constrictor (ARC). IOMP in 2 dogs revealed intrahepatic portal branches only after temporary occlusion of the EHPSS. The remaining 4 dogs were assessed using clinical indicators such as absence of visceral congestion. All 6 dogs showed favorable short- and long-term clinical outcomes, including resolution of neurological and gastrointestinal signs. Follow-up (11–71 months) revealed stable clinical condition in all successfully treated dogs. One dog was not attenuated due to intraoperative signs consistent with PVA. The numeric scoring scale applied to CTA did not assist in surgical decision-making.

Limitations

This study’s small sample size and retrospective design limit the generalizability of its findings. Preoperative CT protocols varied, potentially affecting imaging quality. Portal vasculature assessment relied on a single radiologist, and surgical decisions were subjective. Owner-reported outcomes and variable follow-up further limit objectivity. The absence of standardized intraoperative protocols also precludes full reproducibility. Future prospective studies with larger cohorts and comparative imaging modalities are warranted.

Conclusions

Dogs with EHPSS and no visible portal vasculature on CTA can still be viable candidates for surgical attenuation when intraoperative evaluation supports portal flow capacity. CTA alone is insufficient to distinguish between sPVH and PVA. Intraoperative tools like IOMP provide essential diagnostic information and should be considered in these complex cases. These findings support a cautious but proactive surgical approach in select dogs with CTA-suspected PVA.

Disclaimer: The summary generated in this email was created by an AI large language model. Therefore errors may occur. Reading the article is the best way to understand the scholarly work. The figure presented here remains the property of the publisher or author and subject to the applicable copyright agreement. It is reproduced here as an educational work. If you have any questions or concerns about the work presented here, reply to this email.