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.
Even after treatment and health clearance, in rare cases some former heartworm patients can still test. positive for the heartworm antigen for four to six months after treatment, which is why the dog should. be reâtested in four months and again six months later while being kept on the monthly preventative.