Core77 details the "Longarm," an ingeniously simple contraption designed by a pig farming woman who found herself in charge of 3,000 stubborn hogs. It's just a retractable swath of red cloth, but something about it causes pigs to shy away from it, making it easy to guide them from pen to pen—and easy to clean, something I can attest from my occasional weekends on an uncle's pig farm is a critical feature.
Canadian pig farmer Mary Haugh had a problem; multiple heart attacks put her husband out of commission, and she alone had to somehow control and herd their 3,000 hogs through the barn. Traditional methods of getting pigs to move are to use a stick, an electric prod or a "chase board," a length of wood the farmer wields horizontally to angle the pigs in a particular direction.
The stick and the prod, in addition to being inhumane, are simply not practical solutions for a single man/woman vs. 3,000 pigs, and for that many animals Haugh would need an impossibly long board that no human could reasonably lift and wield.