A pig has both anterior and posterior veins. The veins are part of the pig's cardiovascular system, which also includes its blood, heart, arteries and capillaries.
As a mammal, the cardiovascular system of a pig is very similar to that of a human, making it a useful subject for dissection in educational settings. The fetal pigs utilized in classrooms are not bred nor killed for the purpose of dissection, but rather are a byproduct of the pork industry. Because of their ready availability, each fetal pig can be purchased at approximately one-third of the cost of a cat of the same size.