adult worms live in the right chambers of the heart. The female adults discharge microfilaria into the dog's blood stream where they can live up to 3 years. Transmitted by mosquitoes. Mosquito bites infected animal, ingesting the microfilaria which then change into infective larvae which migrate to the mouth parts of mosquito and then are transferred back in to the next dog bitten. The larvae migrate to the dog's heart, grow into the adult worms.

Heartworms are found most often in dogs. They are parasites that spend their adult life in the right side of the heart and its large vessels. Heartworms are present just about everywhere in the United States. Many locations in the South, East, and West have an extremely high incidence of heartworm disease. There are several areas along the Front Range of Colorado where your dog has a low risk of contracting the disease. Check with your veterinarian for the risk factor in your particular area. To protect your pet against becoming infected with heartworms, your veterinarian can prescribe a preventative medication. If you travel with your pet, ask your veterinarian about the risks of heartworm for the areas of the country that you will be traveling with your pet.

parasites that mature in the chambers of the heart and block major arteries, causing heart failure and death.