Heartworm Info

Susan with Lucy and Melba.

Dogs are considered the definitive host for heartworms (Dirofilaria immitis). However, heartworms may infect more than 30 species of animals, including cats! When a mosquito carrying infective heartworm larvae bites a pet and transmits the infection, the larvae grow, develop, and migrate in the body over a period of several months to become sexually mature male and female worms. These reside in the heart, lungs, and associated blood vessels. Even as immature adults, the worms mate and the females release their offspring (microfilariae), pronounced: (micro fil ar ee), into the blood stream. The time elapsed from when the larvae enter the dog until the minute offspring can be detected in the blood (pre-patent period) is about six to seven months. The male heartworms (four to six inches in length) and the females (10-12 inches) become fully grown about one year after infection, and their life span in dogs appears to be at least five to seven years. Both dogs and cats (and ferrets) should be on a monthly heartworm preventive.