Relationship between intra-uterine bacterial contamination, endotoxin levels and the development of endometritis in postpartum cows with dystocia or retained placenta

A study was conducted to investigate the relationship between intra-uterine bacterial contamination, endotoxin levels and the development of endometri tis in cows that experienced a dystocia or retained their placenta. Fifteen healthy cows, 31 cows with retained placenta (RP) and 13 cows that had dys tocia were clinically examined 1 or 2 days after parturition when a uterine swab for bacteriological examination was taken. In addition, plasma and ut erine lochia samples were collected to determine lipopolysaccharide (LPS) a nd the plasma IgG anti-LPS concentrations. Subsequently, 15 RP and 6 dystoc ia cows were initially left untreated and another uterine swab was collecte d at 2 and 4 wk postpartum. Immediately after calving, RP cows had signific antly higher LPS levels in uterine lochia (average of 2.24 x 10(4) Endotoxi n Units (EU)/mL) as compared to dystocia and healthy postpartum cows (avera ge of 0.10 and 0.26 EU/mL, respectively). However, plasma LPS levels were b elow the detection limit (<0.036 EU/mL platelet-rich plasma) in all groups of cows. IgG anti-LPS levels in plasma were not significantly different bet ween the 3 groups immediately postpartum (average of 26, 16 and 44 Median U nits (MU)/mL)for healthy, dystocia and RP cows, respectively), but they wer e significantly lower when compared to plasma IgG anti-LPS levels of health y cows at more than 2 months postpartum (mean 83 MU/mL). High LPS levels in lochia at 1 or 2 days postpartum were significantly related to abnormal ce rvical discharge, the presence of Escherichia coli, black pigmented Gram-ne gative anaerobes and Clostridium spp. shortly after calving, and Arcanobact erium pyopenes and Gram-negative anaerobes in the uterus at 14 days postpar tum. These results suggest that the presence of E. coli and LPS (endotoxins ) in lochia early postpartum favor the development of uterine infections by A. pyogenes and Gram-negative anaerobes later postpartum. LPS were not obs erved in plasma, suggesting that either they are not absorbed into the bloo d, or they are efficiently detoxified by IgG anti-LPS or other detoxificati on mechanisms. (C) 2000 by Elsevier Science Inc.