I have been a dog groomer for 20 years. I had Frontline and Frontline Plus as pretty much my only available options with the vets offices I worked at. Well the effectiveness continued to go down, with the solution given being "go from once a month to every 2 weeks". I don't know about you, but I can't afford that. The fleas became immune. We have battled fleas for years at my home here in the country. I had been trying everything, and had resorted to bathing the dogs almost daily to get rid of the fleas. But they were still in my home. I tried this as a last ditch effort. My animals stood up, shook, and bodies went EVERYWHERE! I have not seen a flea on them since. And they were bad out here in the country. This is my new favorite go to product.