Pulmonary dirofilariasis in a Japanese hare, Lepus brachyurus angustidens.

A case of pulmonary dirofilariasis in a Japanese hare, Lepus brachyurus angustidens captured in Aomori Prefecture, was first reported in Japan. Two dead worms recovered from the pulmonary artery and detected within an organized arterial thrombus in the lung, were identified as a male and a female young adult Dirofilaria immitis, respectively. Principal lesions in the lung were associated with pulmonary arterial degeneration and consisted of rugose and villous intimal fibrosis, endarteritis with infiltration by numerous eosinophils and mononuclear inflammatory cells, and thrombosis.