Tissue-Invasive<i>Tritrichomonas Foetus</i>in Four Aborted Bovine Fetuses

Abstract

Bovine trichomoniasis is a venereally transmitted protozoal infection that is usually associated with infertility and occasionally causes pyometra and midto late-term abortions. Some cows can carry the infection throughout gestation and remain infected after parturition. Abortions caused by Tritrichomonas foetus are usually diagnosed by microscopic identification of trichomonads in placental fluids, uterine exudate, or fetal stomach contents or by culture. In addition, characteristic placental and fetal lung lesions have been described, and fluorescent antibody and immunohistochemica1 techniques have been used to identify T. foetus in tissue sections. The purpose of this report is to describe 4 cases of tissue-invasive T. foetus infection in aborted bovine fetuses. A male fetus (fetus 1) was aborted in the seventh month of gestation by an Angus-cross heifer and submitted to the Tulare Branch of the California Veterinary Diagnostic Laboratory System (CVDLS) for postmortem examination. At necropsy, spleen and liver were enlarged, and the lungs were firm with patchy, suffusive hemorrhages, interlobular edema, and pale tan areas. Multifocal mucosal necrosis ranging from 3 mm in diameter to 20 x 15 mm was present in the rumen, and focal mucosal hemorrhages were present in the rumen, omasum, and abomasum. Multifocal hemorrhages and segmental hyperemia were seen in the small intestine, and petechial hemorrhages were present in the meninges. A 7-month female fetus (fetus 2) and a 6-month male fetus (fetus 3) were aborted by Holstein cows from the same dairy and were submitted to CVDLS for necropsy and diagnostic tests. Necropsy of fetus 2 revealed 2 liters of cloudy, yellow, viscous fluid in the rumen and abomasum and rare fibrin flecks adherent to the surface of a mottled liver. Fetus 3 had firm, diffusely yellow lungs with interlobular edema and patchy, swollen, hemorrhagic areas in the cranial lobes. The lungs floated in formalin. The rumen was diffisely hemorrhagic with a granular mucosa and patchy to paintbrush serosal hemorrhages. The omasal wall was diffusely reddened and hemorrhagic. Numerous ecchymotic hemorrhages were visible from the serosal and mucosal surfaces of the small intestine. Mesenteric lymph nodes were mildly enlarged and contained focal hemorrhages. Rare hemorrhages were present in the spiral colon and capsule of the spleen. The liver was mottled and slightly yellow.