Prevalence of Heartworm (Dirofilaria immitis) in Coyotes (Canis latrans) in Washington State

A total of 556 hearts from free-ranging coyotes (Canis latrans) in eastern and central Washington State were examined for heart-worms (Dirofilaria immitis) during 2005–2007. Sampling occurred in fall and winter and only heart tissues were examined. No immature or adult heartworms were detected, indicating that heartworm infection is either not currently present in eastern and central Washington, or the prevalence is very low. These data do not support the concept of heartworm transmission in eastern or central Washington State at this time.