I was just curious as to what “chemical” was found in your cat? Because the chemical or active ingrediant in the Hartz Flea and Ticks drops is a chemical that cannot be detected in the blood stream or in anything else for that matter. I would love to know where your vet got that “there is a chemical in his blood,” or where you got that from. Either way, if you people would do your research you would know these things and wouldn’t make yourselves out to look like you don’t have all the information you need. I have posted some other things on this forum, some very truthful and helpful advise, telling people the facts about what this stuff really does. You people are telling me that you have your facts together and you know your facts……..sorry, I just can’t believe that when here is someone who honestly thinks that you can test for pyrethroids in the blood stream? What kind of vet are you seeing? Whoever it is, you need to see a new one, or quit making up things that aren’t true.