Although there is no official ranking of cleanest animal, rather surprisingly, pigs are one of the cleanest animals in the world, according to PBS.org. They are tidy creatures, separating their sleeping and eating areas from their defecation areas.
The common misconception that pigs are dirty and slovenly animals comes from their practice of wallowing in the mud to cool off on a hot day. Because pigs are unable to sweat, they require outside means to cool down their body temperature. In fact, pigs are also considered one of the more intelligent and trainable animals in the world, topping the charts above even dogs and cats.