every 6 weeks , your dogs intestines will never get to deal with the odd worm ,mine only get wormed if i see them in the crap ,about once every year or two .
The worse thing till do is till wait till there is worms in the dogs crap a dog feed raw rabbit and other meat need wormed out alot more often then an dog on meal and tin dog food 6 weeks l worm my dpgs over the hunting season once the season is over the dogs food will change and so will the way l worm them
i think you need wormed