It looked simple enough.

But it was not simple.

Nor was it safe.
In the first instance, pigs were hard to start running.

Oftener than not they would stand, braced, and glare at the oncoming collie from out their evil little red-rimmed eyes; the snouts above the hideous masked tushes quivering avidly.

That meant Lad must circle them, at whirlwind speed; barking a thunderous fanfare to confuse them; and watching his chance to flash in and nip ear or flank; or otherwise get the brutes to running.
And, even on the run, they had an ugly way of wheeling, at close quarters, to face the pursuer.