Functional closure of the ductus venosus during early postnatal life in the dog

Radiographic contrast studies of the ductus venosus performed in 12 pups between the 60th day of intrauterine life and the 5th day after birth indicated that blood flow through the ductus venosus had ceased between the 2nd and 3rd days of extrauterine life. The time of functional closure was not identical with the time of morphologic closure. The functional closure of the ductus venosus was a gradual process and was related to an increase in liver perfusion through the portal vein branches. Both in specimens injected with a radiopaque gum acacia mass and in a corrosion cast of umbilical vein and portal system of the liver, persistence of the lumen of the ductus venosus up to the time of its functional closure was confirmed. The rate of closure in the dog was discussed in relation to that in man and the horse, pig, goat, and sheep.