Without treatment the disease leads to congestive heart failure and death, if dogs have a heavy infections. Dogs with light infections may show no obvious problems. The only way to detect heartworm disease in the early stages is through a blood test. Treatment can be risky, depending on the severity of the disease. Many dogs can be treated successfully with a series of injections that kill the adult heartworms, however in some cases surgery is necessary.
Prevention is best.
Preventing heartworm is much safer and easier than treating heartworm. Effective medications kill infected larvae before they develop into adult heartworms. Dog owners can choose between a monthly pill or a daily pill which is given during heartworm season. However , it is important that dogs, which have gone off the preventative medication during the winter be retested prior to starting back on the medication, if they have traveled to high risk areas during their off time. Locally, since the risk is low, testing every 2-3 years may be more appropriate.