Carol, just because a product label says that it is for ferrets does not automatically make it superior to the ones for cats or sometimes dogs for use in ferrets. If you want to find out which flea products are most trusted for use in ferrets read what the VETS say. In this case I strongly suggest reading posts from AFERRETVET (Dr. Jerry Murray) in http://fhl.sonic-weasel.org [Posted in FML issue 4851]