I did some research two years ago on Frontline vs.  Advantage (product
improvements may have been made since then).  In my opinion, Frontline
is a better product for ferrets, simply based on the toxicity studies and
adverse reaction reports from their testing on kittens.  Both companies
offer the disclaimer that their products have not been specifically
tested for ferrets.  Please, no flames about animal testing, and I also
don't remember the EXACT numbers, but here's what I recall: On the
kitten toxicity studies, toxic levels were reached at about 18xdosage
for Advantage, and about 100xdosage for Frontline.  This tells me that
Frontline is far less toxic.  Plus, Frontline kills ticks and Advantage
does not.  I have used Frontline (in half doses from the cat vial, which is
12-13 drops) for a few years on over 20 ferrets with no adverse reactions.
I tried Advantage on 8 ferrets and got two with a rash, but that's it.  The
Frontline lasts for about 45-60 days at that half dose.
 
- Erika Matulich and the Terrific Ten
[Posted in FML issue 3041]