I am fostering a stray that turned out to have tapeworms. At first I was quarantining him but got lazy before learning of the tapeworm and he's been in common areas shedding tons of eggs, no doubt. If I understand correctly I have to administer Fenbendazole for three days to a known infested dog? Will a monthly or bimonthly administration to my exposed dogs head off their contracting them, or more often? Is there a yard treatment I can apply that would destroy the proglottids or eggs?