(Appeared in Today's Veterinary Practice)
Heartworm disease (HWd), caused by the mosquito-borne nematode Diroflaria immitis, is endemic in most areas of the United states, including urban areas where most of the U.s. population (about 80%) lives. in shelter animals, risk for heartworm infection is thought to be higher than in privately owned pets because stray and surrendered shelter animals are less likely to receive prior veterinary care.