I haven't tried diatom earth on pigs but I used it on a range of other animals to get rid of lice. It worked well on
chickens, quail, pet rats and cats (although that wasn't lice on the cats, but worked anyway). Can't see why it wouldn't work on pigs. If you have some just give it a try, it won't do any harm to the pigs unlike some chemical....
24 acres of grass/bog land in the Scottish Highlands
(Kune kune pigs, pygmy goats, chickens)
Planned: Build a RMH in the animal house, Build a green house