Heartworm disease is a dreaded diagnosis that can be life threatening to our pets. Dogs and cats contract this disease by being bitten by a mosquito that carries immature heartworms, called microfilaria. These are injected into the blood stream when the mosquito is feeding. Microfilaria take about 6 months to mature to adult heartworms which are foot long worms that live in the heart.
Infection leads to clinical signs including coughing, exercise intolerance, lethargy, or inappetence. With large infection and progression of heartworm disease dogs hearts are no longer able to circulate enough blood and there is a significant increase in strain on the heart to keep up with the body’s demands. This is results in heart failure. Adult heartworms can live for 5-7 years which means that if left untreated and not on heartworm prevention, the number of worms and severity of infection can grow exponentially.
Our Indianapolis Veterinarians screen for heartworm disease with a heartworm test. This is a blood test that detects antigens from an adult female heartworm which is different than the stool tests performed for intestinal parasites. Heartworm disease will not be detected by a stool test. The heartworm blood test is done at least annually and can be repeated if preventions have been missed and exposure has happened.
Treatment for heartworm disease consists of a series of injections with a product called melarsomine that targets and kills the adult worms. This must be done under close veterinarian supervision as this has risk for anaphylaxis or embolism from fragments of the dying heartworm.
Heartworm prevention is discussed at every veterinarian appointment to make sure our clients understand the importance of keeping pets protected from this parasite. Heartworm prevention is available in multiple forms – oral, topical, or injectable. It is important to remember that these products must be obtained through a veterinarian as they are by prescription only. Over the counter products labeled for fleas and ticks will not provide coverage for heartworm disease. For more information, please feel free to check out the American Heartworm Society website at