Our veterinarian insists that we give our fuzzies monthly heartworm preventative. She says heartworm is always fatal in ferrets. We live in Michigan, so mosquito season is pretty intense here. I can't remember where I heard it, but I heard it's not a good idea to use dog heartworm preventative. If you chop the pills up to reduce the dosage, you're redistributing the medication unevenly. Our doc makes up some special ferret heartworm stuff using a stock of ivermectin intended for cows. She mixes it into some nummy stuff like gatorade for ferrets. They LOVE it. Check with your vet, of course. If anyone's interested, I could maybe ask my vet for her recipe to give to your vet, though I'm sure there's plenty of wisdom on line here already. -Catherine (Michigan used to be a malarial zone, too. Lots o' swamps. Blech) [Posted in FML issue 1517]