What is commonly called “heartworm disease” is not really a disease at all. Rather, it is an infection by particular internal parasites, Dirofilaria immitis, which live inside of dogs’ pulmonary arteries, the right heart chambers and, in severe cases, the vena cava and veins of the liver. Pulmonary arteries connect the heart to the lungs. The ascending and descending vena cavas are large veins that return blood back up into the heart and lungs from bodily tissues, basically for recycling of biological wastes. Heartworm infestation is a very serious medical condition in domestic dogs. It can be life-threatening if not identified and treated properly and promptly. Even some of the treatments carry the risk of severe and potentially fatal consequences.
Adult heartworms can be extremely large, approaching 15 inches or more in length, and they can live for up to 8 years inside of a dog. Dogs with untreated heartworm disease usually develop congestive heart failure. Dirofilaria can also infect people, causing lung and skin lesions.
Heartworms are transferred from infected dogs to non-infected dogs by adult female mosquitoes. To understand this illness, it is important to understand the parasites’ life cycle. Infection begins when a female mosquito feeds on a wild or domestic dog whose blood contains microfilaria. Microfilaria are the immature offspring of adult male and female heartworms that are living and reproducing within a dog’s bloodstream (in its cardiovascular system). If microfilaria are not ingested by a female
Heartworm disease in domestic dogs typically is classified as follows:Many dogs infected with heartworms show no signs of illness, at least in the early stages of the disease. Often, heartworms are first detected during routine blood testing for other conditions. The most common symptoms of mild to moderate heartworm disease are coughing and general ill thrift.Owners of dogs infected with heartworms may notice one or more of the following signs:Sporting breeds, and other dogs living
Many dogs with heartworm infection show no obvious signs of illness, especially early in the course of their condition. Heartworms are usually diagnosed during a routine blood screening test conducted for an unrelated reason. Initial testing for dogs with a chronic cough or other possible signs of heartworm disease includes a complete blood count, a serum chemistry profile and a urinalysis. Depending upon the results of these tests, the attending veterinarian may recommend an electrocardiograph
Treating heartworm disease can be difficult and dangerous. The therapeutic goals are to kill all adult worms and kill all microfilaria that are present in the dog’s bloodstream. Other goals are to resolve any complications that the dog is suffering and to prevent future reinfection. In considering treatment options, owners and veterinarians must pay special attention to potential adverse drug reactions and the possible serious side effects of live or dead adult worms causing pulmonary