Yes, ferrets can get heartworm and I'm told it is usually 100% fatal when they do. I tried Heartguard tablets first but that turned out to be a week each month battle to get each ferret to eat a whole tablet (since the medication may not be evenly distributed in the tablet & shouldn't be split)... not to mention $20 for six tablet.... Now 20+ ferrets & recommended for year round in this region.... Expensive. There is a reasonable alternative: Quoting from the article "Heartworm Disease in Ferrets" by Dr. Charles Weiss [...] Prevention consists of monthly oral ivermectin, which can be administered in the form of Heartgard (Merck & Co., Rahway, NJ) tablets or liquid ivermectin compounded to yield a dosage of 0.006 mg/kg given orally every month. (This can be compounded by mixing 0.3cc of injectible ivermectin with one ounce of propylene glycol for a concentration 100 mcg/cc.) This formulation is dosed at 0.1 cc/lb once a month. Cut, paste & print this out & take it to any vet. My local (non-ferret) vet mixes it for me. Its about 60ml and costs $7.50. I have a digital fish scale (from WalMart, $29.95) that I tie a string around to hang from and air conditioning vent and hang a WalMart sack from the hook. I weigh each ferret to determine how much he/she should get. (You could also run by your vet's to weigh your fuzzy each month.) The formula for converting pounds & ounces to decimal numbers (which the syringe is marked in) is to divide the ounces by 16 and add that number to the pounds. (Example: 1 pound 9 ounces = 1.56 decimal pounds.... Multiply 1.56 by .1 for the amount to give..... .16) Debi Christy Ferrets First Foster Home [Posted in FML issue 3088]