We'd be sweating like pigs wearing wool if it didn't.

Pigs do have a few sweat glands, but they're not very useful for temperature adjustment. When the mercury rises on the farm, Wilber wallows in cool water or mud, which has the same evaporation effect as sweating.

But pigs don't like very hot climates, because they have very few functional sweat glands, and can hardly sweat at all.