I used Hartz Flea and Tick Powder on my dog and he became so violently ill that I rushed him to the local 24 hour vet hospital. They asked me what kind of poison he had got into and I told them the only thing I had put on him was the flea powder. They told me that the active ingredient in this powder was an organo-phosphate and that is was extremely toxic to pets. She also told me she could not promise me that my dog would even live. I had no idea I was poisoning my dog, I felt so guilty. After about two weeks, $1200.00 in vet bills, and a lot of heartache later, my dog recovered. I learned about this website through a local online petgroup I’m a member of. I am saying this to anyone who has ever even thought of using Hartz flea control products on their pets: DON’T!!! You get what you pay for. In other words, if you pay for crap you get a crappy product. Please use other flea control methods and always make sure to NEVER use anything with any Organo-Phosphates.