Isolation of an Avian Serovar of Chlamydia Psittaci from a Case of Bovine Abortion

Figure 2. Placenta; the cotyledonary villi are extensively necrotic, with clumps of cellular debris (large arrow) and thrombosis (small arrow). HE, bar 5 50 mm. Figure 1. Marked vasculitis involving the arterioles of the placenta. There are fibrinoid necrosis (arrow) and severe infiltrates of the media, composed of leukocytes, mainly neutrophils. The surrounding placental tissue is necrotic. HE, bar 5 80 mm. Many microbial agents have been incriminated as causes of abortion in cattle. Implication of one of these agents in a given case is often problematic. This report deals with abortion in a university-maintained teaching dairy herd that averages about 100 lactating cows. The herd is split into 3 production groups on concrete lots and is fed a total mixed ration according to production level. During previous Dairy Herd Improvement (DHIA) sampling periods, the herd had an average production per cow of 8,325 kg of milk. Average somatic cell count and body condition score are 180,000 and