sweating like a Pig

[branston]

where dose the saying "sweating like a Pig" come from

[Clanad]

The best than can be determined is that it's an Amercanism originating around 1850 or so. It was proceeded by "Sweating like a bull", which, at least, has some reference in actuallity, but pigs do not sweat since they have no sweat glands. Seems it's just a phrase that has no real meaning within itself, but everyone knows it means profuse prespiration... Sorry I couldn't be more deffinitive... Perhaps the venerable Q will have more insight (He has one of the biggest OED's in existence... his own private edition...)

[Quizmonster]

All I can add to the admirable response above is that we think of fat people as being especially sweaty when involved in something effortful. We, unkindly, also often refer to such people as being "fat pigs". Presumably, therefore, we imagined that actual pigs must be prone to the same problem, despite the fact that they do not even - as C explained - sweat at all!
The phrase is just a case of assumption/appearance triumphing over reality.

[Thunderbird+]

As already stated "pigs do not sweat".
Put one on a spit-roast however and slowly rotate it over a fire and it will indeed appear to sweat as the fat is heated from the fire below.
Thats the explanation that I read on here sometime way-back when.