Central Valley Veterinary Hospital
Heartworm Season
What is Heartworm?
Heartworm is a blood-borne parasitic infection that is transmitted by mosquitoes. Heartworm infection was once limited to the southern regions of the United States, however it is now found in most areas of the continental United States, Mexico, and Canada – Including British Columbia. Heartworm is a potentially fatal disease that affects the cardiovascular system. Heartworms mature in the heart and lungs (pulmonary arteries causing severe disease. If a large number of worms are present, blood flow through the heart can become obstructed and lead to heart failure. Blood clots may also form, and in severe cases and embolus (blockage) can become lodged in a small artery. This blockage obstructs normal circulation and can cause sudden death.
How can my dog become infected with Heartworm?
Mosquitoes inject a larval (immature) form of the heartworm parasite into the dog when they feed. The larvae mature into thin, adult worms that are several inches long. Adult heartworms live in the arteries of the lungs (pulmonary arteries) in the heart. Their physical presence causes harm in two ways:
They block the normal forward flow of blood through the heart, causing the heart to work excessively hard and to potentially fail.
They damage the inner lining of blood vessels, which gives rise to blood clots and thus cuts off circulation to parts of the lungs.
Treatment of heartworm disease is time consuming, expensive and can be associated with serious complications depending on the severity of infection. Prevention is a much safer and more cost-effective method, and also helps reduce the prevalence of heartworm in the animal population, thus limiting transmission of the disease.
Prevention
Several tests are available to diagnose heartworm disease in dogs. The test that we recommend is a very simple blood test called 4Dx test. The 4Dx test detects antigens (substances secreted by adult heartworms), as well as it includes testing for ehrlichiosis, Lyme disease, and anaplasmosis. All dogs should have a heartworm test performed if they have not previously received some form of heartworm preventative treatment.
It is very important to administer heartworm prevention to your dog during the summer months in British Columbia. We recommend starting your pet on heartworm medication June 1st and continuing until November 1st. In some areas such as the Southern USA, heartworm prevention is necessary year-round. This is very important to remember if you are travelling to a southern location in the winter. If your dog has not previously received some form of heartworm prevention we will perform a heartworm test to ensure that your pet can be safely started on a prevention plan.
