If your dog is heartworm negative, Ivermectin, used monthly, can definitely be a cheap antiparasitic treatment.
It is the same active ingredient in HeartGuard. HeartGuard is .05% Ivomec. I use it on all of my dogs and if given carefully to a dog with heartworms it will rid them but you have to be extremely careful and start out using minute dosages and gradually build the dog upi to a lethal strength. One more thing DON'T USE Ivomec plus IT IS LETHAL TO DOGS!!!!!!