OBJECTIVE: To determine the ability of Brucella abortus strain RB51 to induce placentitis and abortion in bison after SC vaccination. ANIMALS: 10 pregnant bison cows, 3 to 10 years old and at 3 to 8 months' gestation. PROCEDURE: Pregnant bison cows on a Montana ranch were vaccinated SC with 10(9) colony-forming units of B abortus strain RB51. Two cows, identified prior to the study, were euthanatized and examined 5 weeks after vaccination to obtain optimal histologic samples of placenta. Other cows were euthanatized and examined after abortion. After euthanasia, tissue specimens were collected for histologic and immunohistochemical evaluation. Tissue and fluid specimens for bacteriologic culture were also collected during necropsy. RESULTS: Of 8 cows, 2 aborted at 68 and 107 days after vaccination. Aborting cows had endometritis. Strain RB51 was isolated from reproductive tissues and supramammary lymph nodes. Fetal lesions were not seen; however, fetal bronchial lymph nodes and amniotic fluid contained strain RB51. Cows examined 5 weeks after vaccination had placentitis and endometritis, with numerous bacteria within trophoblastic epithelial cells that were immunoreactive for strain RB51 antigen. Strain RB51 was isolated from placentomes and numerous lymph nodes. Fetal lesions were not seen 5 weeks after vaccination; however, strain RB51 was isolated from numerous lymph nodes and lung, allantoic fluid, and rectal swab specimens. CONCLUSIONS: The vaccine candidate B abortus RB51 has tropism for the bison placenta, and can cause placentitis, which induces abortion in pregnant bison. The vaccine dose used was similar to that being tested in cattle, but may not be appropriate for pregnant bison.

All 37 fetuses of 3 laparotomized pregnant sows at 86, 92, and 93 days of gestation were inoculated intramuscularly through the uterine wall with porcine circovirus type 2 (PCV-2). The sows were allowed to farrow, and blood and tissue samples were collected from their piglets before and after suckling colostrum. Thirteen fetuses from 2 sows at 90 and 103 days of gestation were used as controls. Of the 37 PCV-2 inoculated fetuses, 24 were grossly normal and 13 were mummified, stillborn, or weak-born at farrowing. Infection with PCV-2 was demonstrated in various tissues of grossly normal and abnormal fetuses by virus isolation, polymerase chain reaction, and immunohistochemical methods. Antibodies specific to PCV-2 were also detected from the sera or thoracic fluids of abnormal fetuses and unsuckled normal pigs. No evidence of PCV-2 infection was found in any control fetuses. The present results confirm previous findings that PCV-2 can infect late-term swine fetuses and may cause reproductive abnormalities.

Fatal adverse reactions to vaccination are uncommon and poorly documented. To our knowledge, this is the first case report of fatal adverse reaction to an inadvertent intravenous vaccination in three calves vaccinated against respiratory (Somnustar Ph) and clostridial (Tasvax 8) diseases. All three calves had severe acute interstitial pneumonia with multifocal pulmonary hemorrhages that resulted in fatal respiratory failure. Qualitatively, the pulmonary lesions in these calves were similar to those in septicemic/endotoxemic calves; however, the severity and extensity of pulmonary hemorrhages were of a higher degree than those usually observed in clinical septicemia/endotoxemia. In addition, approximately 30% of the arterioles and small arteries were surrounded by hemorrhages, which occasionally extended around adjacent bronchioles. A unilateral peri-jugular hematoma with recent transmural perforation of jugular vein found in all three calves was believed to have been caused by the injection needle during vaccination, and the fatal pulmonary changes were believed to have been secondary to the intravenous injection of vaccine.