5. Address the envelope. In the lower right third of the envelope, write the name of the person you are sending the letter to. Write the company name on the line below that (if there is a company name).
Once inside a new host, it takes approximately 6 months for the larvae to mature into adult heartworms. Once mature, heartworms can live for 5 to 7 years in dogs and up to 2 or 3 years in cats. Because of the longevity of these worms, each mosquito season can lead to an increasing number of worms in an infected pet.
The larvae enter a new animal's body when it is bitten by an infected mosquito. Larvae mature and migrate to the pet's heart. Worms in the heart mate and produce microfilariae (6-7 months after infection in dogs, 8 months in cats). An important part of a complete heartworm prevention program is testing. All dogs should be tested for heartworm infection before starting a preventive program.