Heartworm Prevention

We just treated our fifth rescue dog this year for heartworm. We thought it may be a good opportunity to talk about heartworm disease and prevention.

Heartworm disease is a serious and potentially fatal condition caused by parasitic worms living in the arteries of the lungs and occasionally in the right side of the heart of dogs and cats and in rare instances – humans! Dogs are extremely susceptible to heartworm – virtually 100% of dogs exposed to infective larvae will become infected. The vector for infective larvae – mosquitos. Mosquitos draw blood from an infected host and pick up the larvae. When they feed on the next mammal, they deposit some of the larvae.

Dogs infected with heartworms may be lethargic, have a persistent cough, reduced appetite and weight loss. Left untreated, the heart can become enlarged and the dog can experience heart failure.

Treatment for heartworms typically costs between $800-$1000 at Indianapolis area vets. The most effective treatment is a two injections of Immiticide spaced 24 hours apart which are administered by injection deep into the muscular area around the spine. OUCH! Dogs may be pretreated with a course of antibiotics and receive a post-injection course of steroids.

In Indiana, we are a moderate infection area, with most larger clinics seeing between 25-50 cases of heartworm disease per year. At last count, our vets at VCA Beech Grove had treated almost 20 cases.

What is frustrating about heartworm disease is that it’s almost 100% preventable with a monthly pill or topical preventative. The preventative isn’t foolproof – we personally know one owner whose dog contracted heartworm disease despite being on a monthly preventative. However, it’s certainly a lot better than the likelihood of your dog contracting heartworms!

It’s best to give the preventative year round in areas like ours, where we can have prolonged moderate weather during the winter and spring. Mosquitos can live in temperatures colder than the spring/summer weather you are used to. You may be tempted to only give heartworm treatments in the warmer months, but again, better to be safe than sorry. Heartworm preventative for a 25-50lb dog costs about $6/month, which is a lot less costly than treatment!

We are diligent about testing all of our adoptable dogs for heartworm disease and administering a monthly heartworm preventative. We hope you will be too!

Thanks to American Heartworm Society for facts and figures!