Caudal vena cava

The caudal vena cava is a large, unpaired vein located in the retroperitoneal space of the abdomen. It begins in the sub-lumbar region, ventral to the lumbar vertebrae, by the union of the right and left common iliac veins (or directly from external and internal iliac veins in some species). From there, it ascends cranially toward the diaphragm and passes through the caval opening of the diaphragm to enter the thoracic cavity and drain into the right atrium of the heart.

Major Tributaries

The caudal vena cava receives blood from several key tributaries as it ascends through the abdomen:

• Common iliac veins (formed by internal and external iliac veins)

• Lumbar veins (segmental veins from the body wall)

• Renal veins (from each kidney)

• Gonadal veins (ovarian or testicular veins):

  • Right gonadal vein drains directly into the caudal vena cava.

  • Left gonadal vein usually drains into the left renal vein.

• Hepatic veins (after passing through the liver)

• Phrenicoabdominal veins (from diaphragm and adrenal region)

Relations and Position by Species

• Dog and Cat:

  • Lies to the right of the abdominal aorta.

  • Embedded in the dorsal aspect of the liver parenchyma, forming the vena caval sulcus.

  • Lies ventral to the vertebral column and dorsal to the intestines and mesentery.

• Horse:

  • Forms from right and left common iliac veins, runs cranially along the right side of the aorta.

  • Passes through the diaphragm at T17-T18, just right of midline.

• Ruminants (Cattle, Sheep, Goats):

  • More variable branching patterns.

  • May receive significant lumbar and azygos tributaries.

  • In the ox, the caudal vena cava is deeply embedded in the liver and may be partially surrounded by a fibrous capsule.

• Pig:

  • Similar to ruminants but with some variation in tributary arrangements.