I've got bad teeth, and was told several times to go to the farmer supply and get a jar of pig penicillin but haven't actually bothered. Pigs are physiologically very close to humans and about the same size, so a dose should be approximately correct. OTOH, if you *do* start penicillin, make sure to go the whole two weeks, bacteria will encyst at random as a survival mechanism and you want to make sure to take it long enough to kill those too.