Evaporation

It is the change from liquid to gaseous state. This process requires a certain amount of energy to break the surface tension of the liquid, thus it is a process that absorbs energy (endothermic reaction). Unlike boiling, it may occur at any temperature.

The loss of temperature by evaporation occurs when a liquid on the surface of an animal (skin or mucosa of the respiratory system) evaporates. For example, when we sweat we are favouring the loss of body temperature by evaporation. Pigs eliminate very little moisture through the skin (they do not sweat), so they need other ways for losing temperature by evaporation, like bathing or getting soaked in ponds, faeces, mud... or increasing their breathing rate.