i always do a weekly health check so thats, check eyes-no weepy/crustiness, cloudiness etc. or anything abnormal, ears-look inside to check it's all normal not too much ear wax etc., nose-no crustiness etc. look at teeth and mouth- no overgrown teeth, no sores etc. and bottom- is it clean etc. nails-check they're not too long, feet are there any sores? no hairloss or lumps, anything like that, it's really just a general check over, you get to know what a healthy pig should be like O0
I weigh weekly too and record it O0 And also if you watch them and get them out regularly i'm sure you'd notice if something was up O0 they don't need vaccinations, some people worm them, i'm looking into this, it's really the owner's choice O0
I always get a pig checked over when i get it, unless it's been at a rescue, because they'll have had vets looking at them O0