How is heartworm infection (dog already has heart worms) treated?
The first adulticide (drug to kill the adult heartworms) for dogs that was developed was thiacetarsamide sodium (Caparsolate®), which contained arsenic. It was given in the vein through a catheter. If any drug got outside of the vein, severe tissue damage was possible. Some animals became quite ill from this drug, and therapy sometimes had to be stopped. Almost all animals had to be hospitalized for the several days of treatment. Melarsomine (Immiticide®), the medication currently used to treat heartworm infection, also contains arsenic. It is given by injection deep in the muscles of the back instead of intravenously. It is less likely to cause side effects than thiacetarsamide and is more effective. The treatment protocol depends on the severity of infection. In less severe cases, the dog may be treated for four months with a heartworm preventive to kill any migrating heartworm larvae and to decrease the size of the female worms. Then an injection of melarsomine is given to kill the
