1-800-Pet-Meds is the largest online animal pharmacy in America.  Pet meds sells both prescription and non-prescription medication, as well as nutritional supplements all at huge discounts.  They also offer free shipping on all order over $39.  You will save up to 25% of your pet meds and that includes heart worm medication like the popular HeartGuard.  I found the most difficult thing was getting a prescription from my vet.  I order HeartGuard every year, and I told my vet that unless they want to match the price write the prescription.  It’s crazy how much more they charge at the vet clinic.  Check to see if there are any special pet meds coupons being offered and save even more at 1-800-Pet-Meds.