Heartworm Disease

Heartworm Disease 1Heartworms are an extremely common internal parasite in most areas of the country and although they are not commonly diagnosed in this area, they are usually fatal to their canine hosts. Heartworms are carried and transmitted by mosquitoes. It takes several years after being infected before dogs begin to show signs of heartworm disease. That is why we recommend heartworm testing annually especially if the patient has been off of heartworm prevention. The test does not detect infections acquired during the previous 6 months.  For this reason, we do not tests puppies, instead we recommend testing at the patient’s first adult annual examination.

To prevent heartworm infection and to limit intestinal parasite infection, Heartworm Disease 2we recommend keeping dogs on heartworm prevention all year round.

Heartworms in cats is more complicated. Cats can contract heartworm disease but it’s not as common in cats. In most cases of feline heartworm disease, only one worm survives to adulthood and the disease becomes self-limiting since the worm will live out its lifetime of 3-5 years and die, causing no long-lasting harm to its host. Additionally, the antigen heartworm test which is what is used with dogs, is not effective in diagnosing heartworm disease in cats. Additional testing can be done but is still only minimally accurate.

Handouts on heartworm disease:
About the Parasite
Heartworm Prevention
Heartworm Treatment

Website of interest:
American Heartworm Society

For more information about dogs and parasites, please visit:


For more information about cats and parasites, please visit: