Basically a dog cannot herd pigs.
As several have said, pigs are not a prey species, so do not repond to agressive stimuli as prey species do.
In nature wild boar have no natural enemies, wander round in small groups quietly in woods, and go compleltly mental if threatened.
So a dog would not work, and at best you wouild end up with injured dog.
As others have also stated, if you do not alreday have good expertience of pigs, iron age are NOT the pig to start with, nor any pigs at the scale you are indicating - 10 sows is a lot of work, and iron age take a lot of skill in handling.