Signs of heartworm disease are not apparent until several years post infection. They include coughing, difficulty breathing, occasionally coughing blood, fainting, and, exercise intolerance. Advanced disease can show abdominal fluid and severe bleeding. Treatment for the disease involves first destroying the adult worms and then eliminating the microfilaria. Risks of therapy are directly related to the quantity of the HW burden and lung involvement which increase the incidence of pulmonary thromboembolism.
Adulticide therapy involves arsenic compounds and hence, potential complications.
Complications include caval syndrome and pulmonary artery infections where the HW burden has been extended into the heart and main pulmonary arteries. Usually prior to adulticide treatment the adult heartworms are surgically retrieved from the heart. Historically intravenous administration of thiacetarsamide sodium has been the mainstay of therapy. Four intravenous injections are given over 2 days. The toxicity of the drug is high to the patient and therefore, hospitalization and monitoring are important.