My uncle asked me to find the cheapest place to buy flea/tick and heartworm medicine for a dog. I never owned a dog so I don't really know much about heartworm. My uncle also couldn't tell me what he used previously for heartworm. He did say he used frontline for flea/tick. He is on a limited budget and his dog was just diagnosed with diabetes so I want to help him find the cheapest place to buy the stuff. Can you buy heartworm medicine online. Is Drs. Foster and Smith the best place. Any help would be appreciated.