Certain species of Sarcocystis can cause abortion in cattle, sheep, goats, and pigs [l-8, 9, 11, 121. The diagnosis of Sarcocystis-induced abortion is difficult to confirm because the organisms rarely are found in fetal tissues or fetal membranes [l, 2, 4, 7, 8, 121. We report a case of Sarcocystis-induced abortion and describe the development of the parasite in bovine fetal tissues and placenta.An adult, multiparous Hereford cow from Frenchtown, Montana, aborted a near-term, female calf weighing approximately 18 kg on 4 March 1981. The calf was necropsied by a veterinary practitioner, and he submitted fresh specimens of fetal lung, liver, kidney, spleen, abomasal content, and placental cotyledon, as well as pieces of lung, liver, kidney, spleen, and cotyledon fmed in 10% buffered formalin to the Montana Veterinary Diagnostic Laboratory.The abomasal content was cultured on tryptose blood (bovine) agar, tryptose agar with antibiotics (with and without crystal violet), and tryptic soy semisolid media. Gram-stained direct smears also were examined. No significant pathogenic bacteria were isolated or identified. Inoculum prepared from fetal lung and spleen did not produce any cytopathogenic effect during three successive passages in bovine kidney tissue cultures. Fluorescent antibodystained frozen sections of fetal kidney were negative for infectious bovine rhinotracheitis virus.Formalin-fxed tissues were trimmed, embedded in paraffin, sectioned at 5 pm and stained with hematoxylin and eosin (HE), Giemsa's stain, and periodic acid-Schiff hematoxylin (PASH). Pieces of lung, kidney, and cotyledon also were embedded in glycol methacrylate, sectioned at 3 pm, and stained with HE.The fetal organs were autolyzed, but the placenta was well preserved. Multiple foci of necrosis were seen in the placenta, mainly involving lamina propria ( fig. 1). There was a mild polymorphonuclear leukocyte and a mononuclear cell infiltrate in the lamina propria of cotyledonary villi and an increase in macrophages in the deeper vascular portions of the lamina propria. Protozoa were seen in the lamina propria of villi and in small arteries of the vascular lamina propria.Focal mononuclear cell infiltrates and necrosis were present in glomeruli and in intertubular connective tissue in cortex and medulla, and protozoa were seen in endothelial cells of glomeruli and arterioles in the renal medulla ( fig. 2). There were extensive congestion and edema in the lung with focal interlobular hemorrhages and focal vasculitis involving media and adventitia. Protozoa were present in endothelial cells of capillaries and small arteries. Spleen and liver were autolyzed and no significant lesions were seen.The aborting cow was clinically normal. Serum, taken from the cow eight days after abortion, was analyzed for antibodies to Sarcocystis cruzi antigen by the hemagglutination test [lo], Toxoplasma gondii by the Sabin-Feldman dye test, Brucella abortus by the plate agglutination test, Leptospira by the microagglutination test, infectious bovine rhinotracheiti...
