A 1-years-old, female Shiba Inu was referred for the diagnosis of portosystemic shunt (PSS). The dog was in good physical condition and there was neither history of incontinence nor signs of lower urinary tract disease. Serum biochemistry showed hyperammonaemia, low blood urea nitrogen and increased levels of serum total bile acid, aspartate aminotransferase and alanine aminotransferase.
CT was performed to determine the presence of portosystemic shunt with a 16-slice multidetector CT scanner (Vantage Elan, Canon Medical Systems, Otawara, Japan). The caudal vena cava (CVC) caudal to the hepatic vein was absent. All systemic veins caudal to the hepatic vein that are normally connected with the CVC were anastomosed with the azygos vein, which was identified as a large vessel (Fig 1A, B). With the portal vein, two shunt vessels were observed from the left gastric vein (splenic vein), one anastomosing to the azygos vein (left gastric-azygos veins shunt) and the other anastomosing to the phrenic vein (left gastric-phrenic veins shunt). The left kidney was located on the left side of the bladder, at the level of L6-L7, and the right kidney was found caudal to the bladder, in the pelvic cavity. Each ureter was inserted correctly into the bladder. The renal arteries anastomosed to the external iliac arteries on both sides, and the renal veins anastomosed to the common iliac vein on both sides (Fig 1C-E). In the thoracolumbar spine, multiple fusions of the vertebrae were observed.
