We've been off and on Drontal for my Dobbie's worms(tape, round, hook) , and he still can't shake them, fortunatly we got him immunized before he picked up heart worms or I'm sure he'd get those too. I'm thinking about ordering a supply of Drontal from petmeds.com and just setting him up on a weekly regiment of dewormer. Will this kick them out of his system? or will it be harmful to him? How is he getting them? Everytime I take him to the vet and he test positive, I feel like the parent @ PTA who's kids keep getting lice. I mean I try and keep his pen clean, he's inside with us for 2-3 hours a night, he refuses to sleep in a cage, I'm kind of at my witts end.