Final answer:
The veins in the forelegs merge to form the right and left venous veins, which then join the body's major systemic veins, transporting deoxygenated blood back to the heart.
Step-by-step explanation:
Veins in the forelegs merge into larger and larger vessels to form the right and left venous veins. As blood exits the systemic capillaries, which are lower in oxygen concentration, they unite to form venules. These venules then join to form larger veins, including the right and left venous veins that continue to merge into the body's two major systemic veins, the superior vena cava and the inferior vena cava. These return the deoxygenated blood to the right atrium of the heart. It's important to note that the venous system in the human body has a complementary pattern to the arterial system, with veins often paralleling the arteries that supply the same regions and organs.