Abstract
Using right intercostal ultrasonography, the ratio of maximum diameter of the portal vein to the aorta (PV/Ao) was measured and compared in a total of 43 dogs with congenital or acquired portosystemic shunts. Group A was composed of 26 dogs with congenital extrahepatic portosystemic shunts, Group B1 was composed of 11 dogs with acquired portosystemic collaterals due to chronic hepatitis, Group B2 was composed of 6 dogs with acquired portosystemic collaterals due to primary hypoplasia of the portal vein, and the Control Group was composed of 20 dogs free of vascular problems. The median values of PV/Ao were: Control > B1 > B2 > A. Considered statistically, the PV/Ao of Group B1 was significantly higher than that of Group A (p<0.01), but there was no significant difference between Group B1 and the Control Group. The PV/Ao of Group B2 was significantly lower than that of the Control Group (p<0.05), but there was no significant difference between B2 and A. In 24 of the dogs in Group A, transverse images of portosystemic shunts were visualized below the caudal vena cava by this method. An enlarged azygous vein was detected adjacent to the aorta in all three dogs with a port azygous shunt. In conclusion, right intercostal ultrasonography is useful in measuring PV/Ao, and detecting an extrahepatic shunt. As an indicator showing the presence of congenital extrahepatic portosystemic shunts, reduced values of PV/Ao might help in diagnosing the disease.
