It does come off if I pull it out of her hair...I brushed her out real good after I noticed the spots in her fur. Today I didn't notice them as much?? So I still went and purchased some advantage for the cats and will be treating them also. Just in case??? I think that would be the best thing....I can't do much more for Maddy since I have resently treated her last Wednesday. As long as everyone is treated it put me a little at ease...