Heartworm disease causes progressive, often fatal cardiopulmonary damage in dogs. Prevention is inexpensive and highly effective, making heartworm one of the most preventable welfare harms in companion animal medicine.
Heartworm disease causes significant chronic suffering as worm burdens damage the cardiovascular system over months to years. Many dogs show stoic tolerance of exercise limitation until late-stage disease. Prevention requires minimal intervention — monthly tablets or topical applications — making the welfare case for prevention overwhelming. Dogs in endemic areas without prevention are at high risk of prolonged cardiovascular suffering.