Successful treatment depends on early diagnosis (before heartworm symptoms are obvious) and the ability to kill all of the adult worms in the heart and arteries of the lungs. (schnauzers-rule.com)
Canine heartworm symptoms are usually not revealed until the disease enters into an advanced stage, resulting in patient infection. (dog-health-handbook.com)
By the time this occurs, most dogs are showing significant heartworm symptoms, and their lives are in danger. (thedrakecenter.com)