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.
Dogs should be tested for heartworm disease annually. The American Heartworm Society recommends the following testing schedule: Puppies under 7 months of age. Heartworm prevention can be initiated without a heartworm test, and they should be tested 6 months after the initial treatment.