Heartworm disease causes severe and progressive cardiopulmonary suffering in dogs. Prevention is far safer and cheaper than treatment, making it a straightforward welfare investment.
Heartworm disease provides an unusually clear welfare calculus: prevention is effective, safe, and inexpensive; treatment involves significant suffering and cost; untreated infection causes progressive cardiopulmonary failure over years. The welfare argument for universal heartworm prevention in endemic regions is compelling. Dogs with heartworm experience insidious, progressive deterioration — initially subtle exercise intolerance that develops into respiratory distress and right heart failure over months to years. Treatment, while curative, requires weeks of strict cage rest during which mobilized dying worms risk pulmonary thromboembolism. The welfare investment in monthly prevention is one of the highest-return actions available to dog owners in endemic regions.