Overview

Please refer to the most recent Canine and Feline Diagnosis, Treatment, and Prevention Guidelines set by the American Heartworm Society available at www.heartwormsociety.org

Heartworm is a parasitic pulmonary artery disease due to Dirofilaria immitis.

Review of the Parasitic Cycle:

• Adult female heartworms release microfilaria into the circulation; these microfilariae can live up to 2 years in the circulation.
• The mosquito is necessary to complete the life cycle of the D. immitis.
• When the mosquito takes a blood meal from the dog, it ingests the microfilaria. After 2 weeks inside the mosquito, the D. immitis is now sufficiently mature to continue development within the dog when injected into the dog on the next mosquito bite (infective L3 stage).
• 4 to 5 months after the D. immitis is injected into the dog, the larvae are present in the heart or pulmonary arteries.
• 6 to 7 months after the D. immitis is injected into the dog, the adult parasite is ready to produce microfilaria.