The elimination of metabolic waste in the pig is the same, as most mammals, but post-birth, it goes out from the ureter. The ureter is the duct by which urine passes from the kidney to the bladder or cloaca. For a fetal pig, as any other mammalian species, it goes through umbilical cord, and then the mother's vascular system moves it back into her bloodstream and then metabolized in the kidneys.