I’m interested in adopting a rescue dog. I’ve seen that some of them have had to have heartworm treatment. Are there any lasting effects once a dog has had heartworm that I would need to be concerned about?

Carol
Sheboygan, WI

Heartworm is a blood parasite of dogs and cats that is spread by mosquitoes. The worms live in the heart and in the pulmonary arteries that lead out of it. The worms traumatize and damage these structures. Heartworm disease is easily preventable by means of oral monthly tablets (Heartgard Plus or Interceptor), or by topical application of Advantage Multi.

Heartworm is endemic in many areas of the United States, such as the Mississippi River basin and the Gulf Coast. Many rescue dogs from these areas will not have received a preventative and therefore are likely to be infested with the parasite.

Treatment is now complicated by the fact that melarsamine, the only approved medication for heartworm, is not readily available. Sadly, even dogs that receive treatment may suffer permanent damage to the heart and pulmonary arteries.

However, there is some good news. Most heartworm-treated dogs adapt to the damage and lead essentially normal lives. A prior diagnosis of heartworm does not always compromise a dog’s future activity and well-being, and it should not discourage you from adopting a rescue dog.

The American Heartworm Society recommends regular heartworm preventatives in all healthy dogs, and so do I. Heartworm is a sad disease, in part because it is completely preventable.