I think the rescue uses it on all their kitties. Jen, can you confirm that? If so, Pouncer, Abby and Harry have all had it, along with all my fosters. It is supposed to get any kind of creepy crawly and keep them from coming.If I had indoor/outdoor cats I'd probably be using it reguarly. As it stands, I might only apply it once a season at the worst flea time.