We have used Advantage with great results, plus the formula is good for dogs, cats, and ferrets. We buy the big dog size because it is the most economical. Our vet set the dose at .20 cc for the ferrets. You could also apply it before going home to make sure they don't bring fleas back with them. I hope that helps..... Kim the Oregon one Kim Reyes Proprietor Broker Garside Realty LLC Direct: (503) 380-4195 Toll Free: 1-877-490-2595 Fax: (503) 469-9737 http://www.kimreyes.com [log in to unmask] [Posted in FML issue 4022]