For people who are truly interested in what is used for heartworm treatment....here you go.....THIS is poison and for me, I will continue to prevent this from happening to MY pups. I find it mind boggling that anyone would subject their pets to this:
American Heartworm Society | Canine Heartworm Adult Heartworm Therapy (Adulticide Therapy)
There is currently one drug approved by the FDA for use in dogs for the elimination of adult heartworms. This drug is an organic arsenical compound. Dogs receiving this drug therapy will typically have had a thorough pretreatment evaluation of its condition and will then be hospitalized during the administration of the drug.