My girls are 10 1/2 months old and doing fabulously. At 18 weeks I took a stool sample from each of them to the vet to check for worms ($25 each!) They were clean. My question is do I need to routinely worm them (like yearly or something?) I donʻt want to give them meds unnecessarily. The guy at the feed store said if I put food grade diamataceous earth in with their feed and in their water that would "worm" them. What do you think?