Heartworm is a serious, life-threatening disease of dogs. It is due to the presence of the adult stage of the parasite, Dirofilaria immitis, in the pulmonary arteries and right ventricle of the dog's heart. The female worm is 6-14 inches long while the male worm is slightly smaller.

Heartworm disease occurs worldwide. Until the early 1970s, the occurrence of heartworm in the United States was primarily confined to the South and Southeastern regions. Today, it is found almost everywhere in the continental United States and is a major threat to the dog population of Canada.

Heartworm disease is not directly passed from an infected dog to a healthy dog. The disease is spread through an intermediate host, the mosquito. Transmission of heartworm depends upon the mosquito population of an area. About 70 species of mosquitoes are capable of transmitting the disease. The more mosquitoes in an area, the greater the chance of heartworm transmission.

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Presently, there are two tests for diagnosing heartworm disease in dogs. Both tests require just a small amount of blood and are performed at most veterinary hospitals.

Dogs should be tested once a year for heartworm disease. The heartworm antigen test is the preferred method. In order to perform the test, a small amount of blood is drawn from the dog's forearm or neck vein. This test detects the presence of the adult heartworm in the pulmonary arteries and / or the dog's heart. The heartworm antigen test is extremely accurate and is a very reliable method for diagnosing heartworm disease.

The second technique used for diagnosing canine heartworm disease is the microfilaria filtration test. This relatively simple test also requires a small amount of blood. The blood is filtered, stained, then examined under a microscope. If microfilariae are seen, the dog is positive for heartworm. Unfortunately, this test does not have the accuracy of the antigen test.

Heartworm is a serious deadly disease of dogs. All dogs living in a heartworm infected region should be tested (annually) for heartworm.

Heartworm prevention is simple. A once-a-month heartworm tablet is available for the prevention of canine heartworm disease.

The staff at your local veterinary hospital can answer all questions pertaining to heartworm.