# Single Posthepatic Portosystemic Shunt Communicated With Internal Thoracic Vein and Azygos Continuation of the Caudal Vena Cava in a Dog

## TL;DR

A rare blood vessel abnormality in a dog was successfully treated with surgery, and CT scans helped identify the complex anatomy.

## Contribution

A case of a rare posthepatic portosystemic shunt with an azygos continuation of the caudal vena cava is reported and successfully treated.

## Key findings

- CTA revealed a rare posthepatic PSS via the persistent left umbilical vein and internal thoracic vein.
- A two-stage surgical ligation led to a favorable long-term outcome over 10 years.
- CTA proved effective in identifying complex vascular anomalies in this case.

## Abstract

Computed tomography angiography (CTA) was performed under general anaesthesia on a 7‐month‐old toy poodle that was referred with the chief complaints of salivation and neurological symptoms. The CTA revealed a rare form of posthepatic portosystemic shunt (PSS) via the suspected persistent left umbilical vein communicating with the internal thoracic vein in addition to an azygos continuation of the caudal vena cava (CVC). The patient underwent surgery for partial ligation of PSS on Day 4 after the initial examination. On Day 71, after the initial examination, a second surgery was performed for complete ligation. Approximately 10 years have passed since the patient's second surgery, and he is still healthy, and generally in good condition. Although the morphology of the shunt in this case was unusual and was accompanied by an azygos continuation of the CVC, a favourable course of treatment was obtained by ligating the shunt vessel. This case report suggests that CTA can reveal the complex morphological characteristics like our case. Surgical treatment in this case resulted in favourable progress, similar to that in dogs with commonly observed extrahepatic PSS.

Computed tomography angiography revealed a rare form of posthepatic portosystemic shunt (PSS) via the suspected persistent left umbilical vein communicating with the internal thoracic vein in addition to an azygos continuation of the caudal vena cava revealed by computed tomography angiography in a 7‐month‐old, intact male toy poodle. The patient underwent two‐stage surgeries for complete attenuation of posthepatic PSS. Approximately 10 years have passed since the second surgery, and he was still healthy and generally in good condition.