I bought 2 kits a few years ago from a breeder in Fla. She gives a bottle of Ivermectin with every kit she sells. I kept them on it for a while then stopped because my vet was concerned about the effects Ivermectin has on breeding animals and I planned on breeding these two. Is there any danger or side effects associated with Ivermectin use in breeding ferrets? I have 12 ferrets, plus kits, all indoor ferrets and have always felt they were safe but now I've decided that it's a whole lot easier to prevent heartworms than to treat them so I would like to get them on the medication. I have several questions: 1) At what age should you start kits on Ivermectin? 2) Dr. Williams mentioned a dosage of 30mcg/lb once a month, does Ivermectin come in a standard concentration? 3) Should all my ferrets be tested before I put them on medication? Is the test the same as for a dog? Cindy [Posted in FML issue 1219]