WHAT CAN I FLUSH OUT FROM ECHOCARDIOGRAPHY AND THORACIC RADIOGRAPHS IN HEARTWORM INFECTED DOGS?

Despite the name “Heartworm” suggests a primitive cardiac involvement as the natural localization of the worms and the first damages are in pulmonary arteries, heartworm disease should be considered a primary pulmonary disease that in the last stage only may involve right cardiac chambers.
In Heartworm infected dogs the reduction of compliance and gauge of pulmonary arteries, that can be also occluded by either thromboembolism or severe villous proliferation, results in a hypertensive pulmonary state and, as a consequence, in an increased after load for the right ventricle which can induce “cor pulmonare” and right cardiac congestive heart failure1,2.
Based on the pathogenesis the clinical evolution of heartworm disease in dogs is usually chronic.
Most infected dogs do not show any symptoms of the disease for a long time, months or years, depending on worm burden, individual reactivity and exercise, as arterial damages are more severe in dogs with intensive exercise than in dogs at rest. Signs of the disease develop gradually and may begin with a chronic cough.
Acute symptoms as in course of Caval syndrome and/or thromboembolism may arise in a late stage of the infection only.
Together with antigen with history, clinical examination and antigen testing thoracic radiographs and echocardiography are pivotal for staging the disease and choosing the best therapy in infected dogs.