Chlamydiosis in a beef herd

Chlamydial infection in a large beef herd is illustrated and discussed. The pre-natal and post-natal losses that occurred during 1972 are highlighted. Total pre-natal losses for the nine calving herds comprising 2,915 animals varied between 3,7% and 12,4%. Between 1,2% and 11,4% of the calves born alive in the nine herds died before weaning with 70% of the losses occurring within the first three weeks of life. Chlamydial organisms were demonstrated in pre-natal and post-natal losses from all nine herds. Clinical manifestations and lesions involving the intestinal, respiratory, nervous, skeletal, reticulo-endothelial and urinary systems were observed in chlamydia-infected calves. Invariably at autopsy in chlamydia positive cases there was some degree of a fibrinous inflammatory process present. Serological evidence showed that chlamydial organisms had been present on both farms prior to the 1972 investigations.