Canine Heartworm

DISEASE INFORMATION

What are the signs of canine heartworm?

Domestic dogs may have a chronic cough, low stamina, or respiratory distress when infected. Heavy infestations may lead to heart failure.

Heavy infestations can result in worms blocking and irritating the pulmonary artery, causing subsequent enlargement of the right side of the heart and decreased lung efficiency. Congestive heart failure may occur, leading to lung, liver, and kidney damage.

How is canine heartworm diagnosed?

On necropsy, diagnosis is by through recovery of adult worms from the heart. In live animals, diagnosis is through an x-ray or a blood test; microfilariae (tiny worms) can be seen in a blood sample once the infestation is heavy enough.

Significance for wildlife management

Coyotes can be stressed by heartworm infestation, and occasional mortality occurs; however, population-level effects are unlikely because coyotes usually do not show signs of the disease. Foxes and bears are very uncommon hosts of the disease. Based on the best information available, the most probably infection source for domestic dogs is other dogs, rather than coyotes.

How is canine heartworm treated?

Heartworm preventive medication is available for domestic dogs; this is the best control. Treatment of animals infected with heartworm is costly and dangerous, but is successfully done routinely. There is no control or treatment feasible to use on wildlife.

Does canine heartworm pose a risk to people or other animals?

Occasionally, people have been diagnosed with a single heartworm in the lung; it is rarely found in the heart in humans. It does not generally cause disease symptoms in people and it’s occurrence is such a rare event that it is not a major public health concern.

Canine heartworm can affect domestic dogs, as well as coyotes, red and gray foxes, and black bears.​​​