Dirofilaria immitis from the Right Ventricle of an Equine Heart

Abstract

In a 3-year-old Thoroughbred colt, a worm was detected from the right ventricle and identified as Dirofilaria immitis. The worm was found to measure 156 mm in length and 675 p in width. The morphological findings and measure ments of the worm were similar to those of 3 female worms of Dirofilaria immitis which had been detected from an infected dog 150 days after artificial infection. Histologically, a nodule consisting of plasma cells and lymphocytes, small hemorrhages, edema, and separation of muscle fibers were shown in the cardiac papillary muscle around which the worm had twisted. It was speculated that such histological lesions might have been caused by the parasite of Dirofilaria immitis.