Lego can afford to play it fast and loose with details due to their blockish nature. So, you wouldn't expect Lego ANIMALS to be "anatomically correct." But that's changing as their sets become increasingly intricate.
They recently introduced a "Majestic Tiger," which has impressive detail . . . including Lego's first ANUS. Yes, the tiger has a small, circular pink piece that fits underneath its tail. The specific part is also used for flowers, among other things.