Hi, Someone asked if it was necessary to give ferrets heartworm preventative. The answer is YES! The following is a quote from A Practical Guide To Ferret Care c1996, by Deborah Jeans (published by Ferrets Inc.), page 37: HEARTWORM PREVENTION Heartworm is a parasite that is transmitted to your pet by a mosquito bite. Heartworm preventative is given monthly and is a must because heartworm disease can be fatal! Even if your pet does not go outdoors, mosquitoes do come inside. It only takes 1 infected mosquito to inject heartworm larvae into a ferret's bloodstream. The larvae develop into adult worms (5" - 6" long) eventually lodging in the heart, leading to the ferret's death. HEARTWORM DISEASE WARNING SIGNS * Chronic cough * Lethargy * Labored breathing * Fluid accumulation in the abdomen * Fainting * Bluish color to tongue, gums and lips * Kim [Posted in FML issue 1734]