I wouldn't normally write a bad review for a product, however, I really believe this is not worth the money. It essentially did little to nothing to kill or prevent fleas on our pets. I can safely say that most of the fleas on our pets did not die or even leave the animal. We tried this for a three month period and it was absolutely useless.In a comparison, we switched to K-9 Advantix II and the difference was night and day!Same animals, location, weather, etc...The Frontline Plus honestly did not work. I may have well administered tap water instead of Frontline Plus.The K-9 Advantix II worked almost immediately.PLEASESave your money! DO NOT WASTE IT on this product. I can't imagine how two products (FRONTLINE - ADVANTIX)claiming to do essentially the same thing, can be so vastly different with results. If I had to rely on Frontline, I would simply not use anything.