Heartworm disease (Dirofilaria immitis) is a preventable but potentially fatal parasitic condition causing significant cardiopulmonary welfare compromise, with prevention far superior to treatment for both animal welfare and owner cost.
Heartworm disease creates a preventable welfare burden that is entirely attributable to human action or inaction — no dog develops heartworm without human failure to provide prevention. The cardiopulmonary compromise from advanced heartworm infection causes chronic suffering from exercise limitation, respiratory distress, and cardiovascular deterioration. Treatment is effective but involves its own welfare costs: the necessary exercise restriction during melarsomine therapy is psychologically and physically challenging for dogs, and post-adulticide pulmonary thromboembolism represents a treatment-associated risk. The welfare calculus is unambiguous: monthly prevention is safe, effective, and protects the dog from all of these welfare costs at minimal burden. Owner education about prevention as a welfare responsibility rather than optional health expense is the primary advocacy target.