Heartworms are only transmitted by the bite of an infected mosquito. In rare cases, people can get heartworms after being bitten by an infected mosquito. But because people are not a natural host for heartworms, the larvae usually migrate to the arteries of the heart and lungs and die before they become adult worms.

What are the first signs of heartworms in dogs?

Signs of heartworm disease may include a mild persistent cough, reluctance to exercise, fatigue after moderate activity, decreased appetite, and weight loss. As heartworm disease progresses, pets may develop heart failure and the appearance of a swollen belly due to excess fluid in the abdomen.

How do dogs get heartworm disease?

Dogs Get Heartworms from Mosquito Bites

After an infected mosquito bites a dog, the larvae develop into adult heartworms in about six to seven months. They live in the dog's heart, mate, and produce offspring called microfilariae that live in the dog's blood vessels.