Ultrasonography and portography in the diagnosis of shunt portoazigos in a dog - case report

ABSTRACT Portosystemic shunt (PSS) is an anomalous vascular connection between the portal venous system and the systemic circulation. These deviations connect the main portal vein (PV) or some portal branches to the vena cava (VC) or, less commonly, to the azygos vein (AV). The purpose of this case report was to describe the diagnosis of PSS in a dog classified as porto-azygos. This diagnosis is considered uncommon compared to other portosystemic shunts using ultrasonography and portography. The subject was a male dog, Yorkshire, 8 months old, presented neurological signs characterized by head press, ataxia, tremors and episodes of temporary blindness and deafness. Ultrasonographic examination revealed a dilated and curved anomalous vessel with approximately 0.6cm of diameter and turbulent flow seen through pulsed and color Doppler, and segmental dilation of the azygos vein. The portography revealed enhancement by iodinated contrast in the jejunal vein, the portal vein and an anomalous vessel flowing towards the azygos vein in the craniodorsal region of the abdomen. The PSS was surgically corrected with an ameroid constrictor. Ultrasonography and portography were effective at detecting and characterizing the portoazygos shunt despite some limitations.摘要 门体分流术（Portosystemic shunt, PSS）是指门静脉系统与体循环之间形成的异常血管连接。此类血管变异可将主门静脉（PV）或部分门静脉分支连接至腔静脉（VC），少数情况下也可连接至奇静脉（AV）。本病例报告旨在描述1例确诊为门奇分流的犬的诊疗过程。相较于其他类型的门体分流术，采用超声检查与门静脉造影术诊断门奇分流的案例较为罕见。受试对象为1只8月龄的约克夏公犬，其临床表现为头部抵压、共济失调、震颤以及一过性失明与耳聋发作。超声检查可见1根直径约0.6cm的扩张迂曲异常血管，脉冲多普勒与彩色多普勒成像显示其内存在湍流，同时可见奇静脉节段性扩张。门静脉造影显示，空肠静脉、门静脉以及一条通往腹部前背侧区域奇静脉的异常血管均被碘对比剂增强显影。本病例采用阿米罗特缩窄器（ameroid constrictor）进行手术矫正门体分流。尽管存在一定局限性，但超声检查与门静脉造影术均可有效检出并明确门奇分流的特征。