Dynamics of the acute uterine response to infection, endotoxin infusion and physical manipulation of the reproductive tract in the mare.

The uterine responses after the infusion of saline (PBS), a bacterial suspension, or lipopolysaccharide derived from Escherichia coli, and after stimulation of the reproductive tract were compared. All infusions provoked a response involving both serum proteins and leucocytes. Protein levels peaked within a few hours of infusion, whereas leucocyte concentration peaked later at around 6 h. Bacterial recovery from the uterus followed a similar pattern, with recovery falling dramatically by 12 h. In mares known to be susceptible to infection large numbers of bacteria were again recovered after 24 h. No differences were apparent between resistant and susceptible mares in protein or leucocyte concentrations. Stimulation of the cervix and uterus resulted in a protein and neutrophil response. In contrast, vaginal stimulation failed to provoke the uterine defences.