Dave Sweet mentioned some differences between Frontline and Advantage in Saturday's FML. I just have one small addition to what he said. Frontline is also available in a spray bottle, which in my opinion, is perfect for ferrets. The dosage is 1 pump per pound of body weight. I've used it on my ferrets (and cats) with great success. This is actually much cheaper than either the Frontline or the Advantage spot on. A 250ml bottle costs about $20 (YMMV) and will last a good year for ferrets only. I have 5 ferrets and 4 cats, all of who get treated, so the bottle only lasts me about 2 months. That's $10 bucks a month for 9 animals. The spot on costs about $30-$40, and comes with 3 vials, each good for one cat or 2-3 ferrets (again, YMMV). The benefits of the spot on is that it is much easier to apply, but the spray on is cheaper. If you can afford it, I'd certainly recommend the spot on because of it's ease of use. If money is an object, I'd suggest the spray on because it's cheaper (and works just as well). I hope this helps. Tony and Nicky, Toby, Lucy, Kayla & LuLu [Posted in FML issue 2010]