Computed tomographic anatomic variations of the phrenicoabdominal veins in cats

There are no published reports describing the anatomic variations of the phrenicoabdominal (PhAbd) veins in cats. The aim of this study was to evaluate the anatomic variations of the PhAbd veins in cats without adrenal disease. This is an anatomic study. Abdominal CT images of cats acquired from January 2021 to February 2023 were retrospectively reviewed. Inclusion criteria were the presence of pre- and postcontrast CT images of the abdomen and the absence of any abdominal diseases that compromise the left and right PhAbd veins visualization. A total of 128 cats were included. Three different vascular anatomic variations were found in the distal pericaval segment of the left phrenicoabdominal (LPhAbd) vein. In the first type, found in 65 cases (50.8%), the LPhAbd vein drained directly into the caudal vena cava. In the second type defined IIa, found in 25 cases (19.5%), the LPhAbd vein drained into the distal third of the left renal vein, less than 5 mm from its opening into the caudal vena cava. In the third type defined IIb, found in 38 cases (29.7%), the LPhAbd vein drained into the distal third of the left renal vein, more than 5 mm from its opening into the caudal vena cava. The right phrenicoabdominal vein had a consistent path and drained into the caudal vena cava in all cases. The knowledge of these vascular variations is expected to help the surgeon during adrenalectomy due to masses with vascular invasion in cats.