here we have "issues" with worms. Perhaps its because we're in ag country with lots of livestock. wild rabbits here have liver parasites, so even humans won't eat the rabbits. If my dog killed a wild bunny and ate it, he'd be getting meds for the parasites because those buggers transfer into other mammals. Heart and liver parasites are rampant here and yes you can have pets and humans for that matter having parasites you don't see. If you've ever watched the slow death of your dog, due to liver failure... you may have a different perspective. Watching them get to the point of seizures and looking at you in confusion and you not being able to do anything to ease their pain is horrifying. Sorta changes how you view "prevention". ALso who said I was giving chemicals? Bad assumption. I just believe in Worming. Nothing was said about commercial poisons in the form of worming meds.