I've been looking at websites that let you order heartworm medicines without a prescription. Has anyone had any experiences, good or bad with this? These websites offer both heartgard and other generic medicines. I'm thinking about ordering from one of the websites but I don't want to get ripped off or get something that would not work on my dogs. I would greatly appreciate any advice. I've thought about going to the farm supply store and getting ivermectin for horses or pigs but I'm nervous about doing that, I probably would not get the dosage correct for using it on the dogs.