hi, I read about a medication called Revolution, it is for heartworm and fleas. Has been used in Europe for a while. I see it can be ordered on the internet, does not require a vet to order, and has a good track record. Check various sites for best price. I intend to start my dogs on this when I am out of my current supply from the vet. I found this info in woman's day or family circle mag. The price is less than one dose of the better flea meds, and it is a topical medication. Hope this helps, i know it will for me. Like this site as well as backyard chicken site, wonderful info and support. Claire