Heartworm disease causes severe, progressive, and often fatal cardiopulmonary damage in dogs, yet it is almost entirely preventable through monthly or annual prophylactic medications.
Heartworm disease represents one of the most straightforward preventable welfare failures in companion animal medicine. The disease causes months to years of progressive suffering as worm burden increases, eventually causing severe cardiopulmonary compromise. Treatment of established infection is itself a significant welfare burden — requiring strict rest, painful injections, and recovery monitoring over months. Preventive medication is so effective and affordable that heartworm disease in a dog with regular veterinary access represents a failure of prevention rather than an unavoidable illness. As mosquito ranges expand with climate change, geographic areas previously considered low-risk are seeing increasing prevalence. Year-round prevention is increasingly recommended as the default rather than seasonal treatment in affected regions.