Congenital interruption of the portal vein and caudal vena cava in dogs: six case reports and a review of the literature.

OBJECTIVE

To describe six dogs with congenital abnormalities involving the portal vein, caudal vena cava, or both.

ANIMALS

Six client-owned dogs with congenital interruption of the portal vein or the caudal vena cava, or both.

METHODS

Portal vein and caudal vena cava anatomy was evaluated by contrast radiography and visualization at surgery. Vascular casts or plastinated specimens were obtained in three animals.

RESULTS

Portal blood shunted into the caudal vena cava in four dogs and the left hepatic vein in one. Two of these five dogs also had interruption of the caudal vena cava with continuation as azygous vein, as did an additional dog, in which the portal vein was normally formed. Portal vein interruption was present in 5 of 74 (6.8%) dogs with congenital portosystemic shunts evaluated at the Veterinary Teaching Hospital during the study period.

CONCLUSIONS

Serious malformations of the abdominal veins were present in more than 1 in 20 dogs with single congenital portosystemic shunts.

CLINICAL RELEVANCE

Veterinarians involved in diagnosis and surgery for portosystemic shunts should be aware of these potential malformations, and portal vein continuity should be evaluated in all dogs before attempting shunt attenuation.