Dj. Brockman et al., UNUSUAL CONGENITAL PORTOSYSTEMIC COMMUNICATION RESULTING FROM PERSISTENCE OF THE EXTRAHEPATIC UMBILICAL VEIN, Journal of Small Animal Practice, 39(5), 1998, pp. 244-248
An unusual congenital portosystemic shunt was identified in one dog an
d two cats with clinical signs and laboratory evidence of hepatic dysf
unction. In all the animals, the abnormal vessel arose from the portal
system between the left medial and quadrate liver lobes and travelled
within the falciform fat, exiting the abdomen through the caudal vent
ral left diaphragm. The intrathoracic course of these vessels was not
established. The anatomical location of this anomalous vessel may have
hindered attempts at ultrasonographic identification since it was not
visualised before surgery in any of the animals. In addition, while t
he anatomical location of the vessel may facilitate rapid identificati
on and surgical attenuation, it could predispose the vessel to trauma
during the coeliotomy approach. It is hypothesised that this form of p
ortosystemic communication results from failure of a portion of the le
ft umbilical vein to degenerate during embryogenesis. This is in contr
ast to other forms of congenital extrahepatic portosystemic shunt that
are presumed to be developmental errors resulting in an abnormal comm
unication between the embryonic vitelline and cardinal venous systems.
The prognosis for animals with the vascular anomaly reported here is
probably similar to that for animals with other forms of congenital po
rtosystemic shunt.