Diagnostic studies of the fetus, placenta and maternal blood from 265 bovine abortions.

During 1981, the fetus, placenta and maternal serum were received from each of 265 bovine abortions. These specimens were examined using histopathological, histochemical, bacteriological, mycological, endocrinological, immunological, serological and virological techniques. The cause of abortion was identified in 98 (37%) cases. Of these diagnosed abortions 27 (28%) were due to infection with fungi, 17 (17%) to Salmonella spp, 11 (11%) to Campylobacter fetus and 10 (10%) to Corynebacterium pyogenes infection. Of the remaining 33 (34%) diagnosed abortions 8 were due to Leptospira sp, 5 due to protozoan (probably Sarcocystis) encephalitis and 20 due to miscellaneous bacterial infections (including Brucella abortus) and fetal deformities. Bovine virus diarrhoea virus was isolated in 5 (2%) abortions, however the significance of the isolations was not known. Infectious bovine rhinotracheitis virus and chlamydia were not identified as causal agents in any abortion. In 18 (7%) abortions no definite etiologic agent was identified despite pathological findings suggestive of infection. Fetal heart blood serology and immunoglobulin values were not reliable indicators of infectious abortion. Of the remaining 149 (56%) abortions, 17% had high maternal serum cortisol levels and twin fetuses occurred in 9%.