Definition of Heartworm
Heartworm disease refers to infection by Dirofilaria immitis , which are parasites that live in the right heart, chambers, the pulmonary arteries and, in severe cases, the vena caval and liver veins. Immature heartworms are transferred from infected to non-infected dogs in the saliva of adult female mosquitoes. The parasites are most prevalent along the southeastern Atlantic and Gulf coasts, although they have been found in all parts of the United States. Adult heartworms can approach 15 inches in length. A single mature female can produce up to 5,000 offspring in one day, each of which can survive in a dog’s bloodstream for about 8 years, producing more offspring. These parasites can infect people, although this is rare. Heartworms in dogs can be life-threatening if not treated properly. When a dog receives drugs that kill heartworms, the dead and dying parasites can clog blood vessels, wrap around heart valves and mechanically interfere with heart function. Fortunately, heartworm disease is usually preventable or medically manageable.