I know it is advised that ferrets get the cat dose of Revolution which is 45 mg. But I wanted to say that the cheapest option is to get the big dog vials, especially if you have multiple ferrets. I just got 3 of the largest dog vials (240 mg). I am not going to use 45 mg per ferret because we do not have heartworm in the UK, I just want to try it for ear mites really so I've decided to use 12 mg per kg which is double the general recommended minimum dose. So the 3 vials are going to do my ferrets, dogs, cats and skunks. But I was shocked to see the difference in price (i.e. how much *cheaper* the large vials were), 3 puppy/ kitten vials (15 mg) were approx. $18 and 3 large dog vials (240 mg) were approx. $27. 3 cat vials were approx. $21. I don't know how these prices compare to the US but considering 3 cat vials will treat 3 ferrets and 3 large dog vials will treat 15 - 16 ferrets at the 45 mg dose... If anybody wants to do this but is finding the maths bit daunting (figuring out the dose), I'm happy to help. Ulrike -- [log in to unmask] [Posted in FML 6093]