The adult heartworm lives in the right chamber of the heart and pulmonary artery that routes blood through the lungs where carbon dioxide is removed and oxygen is added to the red blood cells. Infected hearts sometimes, become so full of worms that only a trickle of blood can get through. Mosquitoes are the main carriers of the disease. A single mosquito bite may imply a heartworm infection. Mosquitoes bite an infected dog and pick up some microfilaria from the blood meal. The microfilaria lives for about two weeks in the salivary glands of the mosquito.
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