We do the belly rub first, if that doesn't work a couple of cans of Guinness is our next port of call
if it ever gets to the time that this doesn't work (which it might for my boars de-tusking) it'll be a shot of stresnil.
Ours come in onto concrete in the winter, so mostly they wear them down a bit then, we've only got one sow who needs a wee trim this year (she's 6)
I've seen lots of micro pigs with feet problems and overgrown nails, this has led me (perhaps wrongly ?) to the conclusion that pigs
seem to suffer more from it if they're overweight (cos every one of them was)