Dog Heartworm Treatment and Prevention in Shelter Populations

Heartworm disease is highly prevalent in warm-climate shelters and effective prevention and treatment programs save thousands of lives.

Key Facts

Heartworm disease is caused by Dirofilaria immitis transmitted by mosquitoes and is endemic throughout the southern US
Adult worms live in the heart and pulmonary arteries, causing severe cardiopulmonary disease if untreated
Prevention with monthly heartworm preventives (ivermectin-based or moxidectin) is highly effective and affordable
Treatment (immiticide - melarsomine injections) involves strict exercise restriction for 2-3 months following injections
Shelter heartworm treatment programs have demonstrated that treating heartworm-positive dogs increases adoption rates
The slow kill method (monthly preventive plus doxycycline) is used in some shelters due to cost constraints but is less reliable
Heartworm testing should be performed annually, especially in southern states with year-round mosquito activity

Welfare Considerations

Untreated heartworm disease causes progressive exercise intolerance, coughing, weight loss, and eventually heart failure. Dogs die slowly from this entirely preventable condition. Shelter treatment programs save thousands of dogs who would otherwise be euthanized due to heartworm-positive status, transforming their welfare outcomes.

What You Can Do

Give heartworm prevention year-round as recommended, especially in southern states
Annual heartworm testing is essential to catch infections before significant damage occurs
Support shelters with heartworm treatment programs that save positive dogs
Donate to organizations providing low-cost heartworm prevention to underserved communities
Advocate for year-round mosquito prevention education in heartworm-endemic areas