From the February 2021 Newsletter:
Fetal tissues and placenta from an Angus calf that was aborted two weeks prior to the due date were examined. The heifer dam was reported to be lethargic and this was the second abortion on site in a group of about 25 heifers.
The field necropsy did not reveal any gross lesions. Microscopically, however, we found variable regions of mixed inflammation in the lung (Figure a). Additionally, we found a placentitis characterized by degenerate neutrophils within the chorion (Figure b), along with numerous smudged bacterial colonies within the chorion and cotyledon (Figure c). Cultures of the lung, liver and abomasal fluid yielded high numbers of Campylobacter fetus bacteria.
Campylobacter abortions in cattle can be due to C. fetus spp. venerealis, C. fetus spp. fetus or C. jejuni. The latter two bacteria typically occur sporadically and are transmitted hematogenously from the gastrointestinal (GI) tract of the dam. C. fetus venerealis is different in that it is a venereally (sexually) transmitted disease. Bulls are subclinical carriers, while heifers may have higher rates of infertility than older cows. Further PCR testing identified the isolate to be C. fetus spp. fetus. Interestingly, the Merck Veterinary Manual lists C. fetus venerealis and C. fetus fetus as causes of bovine genital campylobacteriosis. Experimental infection is necessary to determine if a particular strain of C. fetus fetus is associated with infertility.
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