Where is heartworm disease found?
Heartworm disease occurs worldwide in tropical, subtropical, and some temperate regions. Until the late sixties, the disease was restricted to southern and eastern coastal regions of the United States. Now, however, cases have been reported from dogs native to all 50 states (Figure 1). For most of North America, the danger of infection is greatest during the summer when temperatures are favorable for mosquito breeding. In the southern U.S., especially the Gulf Coast and Florida, where mosquitoes are present year-round, the threat of heartworm disease is constant.