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.1 For more on the dangers and prevention options of mosquito, flea and tick bites visit the Why Wait For The Bite section on Good News For Pets.
1American Heartworm Society http://www.heartwormsociety.org/pet-owner-resources/canine-heartworm.html