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.
How long before dog heartworm symptoms show? How long can a dog have heartworms before symptoms of the dog heartworms can be seen? By: Sandra Parker El Segundo, CA Replied on 04/19/2011 The answer to this question is tricky because there are no hard and fast rules about the manifestation of symptoms of heartworm disease in dogs.