Heartworm disease causes severe suffering and a slow, painful death in untreated dogs, yet is almost completely preventable through monthly or annual preventative medications available from veterinarians.
Heartworm disease causes a slow, progressive, and ultimately fatal deterioration in cardiac and pulmonary function. Dogs in the early stages show subtle exercise intolerance that owners may attribute to aging. As disease progresses, breathing difficulty, persistent coughing, and exhaustion become severe. Treatment of established infection involves several months of restricted activity and injectable medications that themselves cause pain, with the risk of serious complications from dying worms obstructing blood vessels. The profound welfare disparity between prevention — a simple monthly treat or annual injection — and the suffering of untreated disease makes heartworm one of the most important preventable welfare problems in companion dogs.