Pathogenicity of Bacillus cereus for Pregnant Ewes and Heifers

SUMMARY Five ewes, pregnant 90 to 110 days, were inoculated intravenously with approximately 5.1 × 105 Bacillus cereus organisms. Four of the ewes aborted dead lambs 3 to 8 days postinoculation (pi). The other ewe died on pi day 4 after having fever, tachycardia, tachypnea, and central nervous system (cns) disorder. Of 6 heifers pregnant 7 months, 2 (group 1) were inoculated intravenously with approximately 8 × 106, 2 (group 2) with 8 × 105, and 2 (group 3) with 8 × 103 B. cereus organisms. Heifers in groups 1 and 2 aborted dead calves on pi days 7 through 12. Other clinical signs were mild. Heifers in group 3 had normal calves at term. Aborted lambs and calves had varying degrees of autolytic change, along with blood-tinged ascites, hydrothorax, hydropericardium, and subcutaneous edema. Necrotic placentitis was the only microscopic lesion found in each case. Bacillus cereus was isolated in pure culture from the tissues of the dead ewe and all aborted lambs and calves.