Effect of intrauterine infusion of Escherichia coli endotoxin in postpartum pony mares

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Abstract
SUMMARY: Fifteen pony mares were assigned to 1 of 3 treatment groups after foaling: Group 1, 35 ml of sterile saline solution was infused into the uterine lumen within 24 hours after parturition (6 mares); group 2, 300 mg of Escherichia coli endotoxin was infused into the uterine lumen within 24 hours after parturition (6 mares); and group 3, 300 mg of E coli endotoxin was infused into the uterine lumen between 72 and 96 hours after parturition (3 mares). Rectal temperatures were taken at −1, −0.5, 0, 0.5, 1, 1.5, 2, 3, 4, and 5 hours after treatment. Venous blood samples were also taken at these times for routine wbc counts. Data were analyzed as a repeated measurement design with linear and quadratic orthogonal contrasts performed where significant time and interaction with time occurred. Pretreatment averages of total wbc and neutrophil counts were compared with their nadir posttreatment averages by a t test when treatment-by-time interaction was significant for the parameter. Rectal temperature (37.9 ± 0.1 C) remained stable and did not vary among treatment groups after intrauterine infusions. In contrast, total wbc and neutrophil counts did vary among treatment groups across time. However, for treatment groups 1 and 3, neither blood total wbc count nor neutrophil count after intrauterine infusions was different from pretreatment observations. In group 2, total wbc count decreased (P < 0.10) from a pretreatment average of 11.5 ± 0.4 × 103 cells/mm3 to a nadir concentration of 10.0 ± 0.6 × 103 cells/mm3 by 60 minutes after infusion of endotoxin into the uterus. Blood neutrophil count in group 2 decreased (P < 0.025) from a pretreatment average of 7.4 ± 0.4 × 103 cells/mm3 to 5.4 ± 0.6 × 103 cells/mm3 by 2 hours after treatment. Endometrial biopsy samples were taken from 3 mares in each treatment group after the last blood samples were obtained. Biopsy samples were examined by scanning electron microscopy. The mucosal surfaces of endometria from all treatment groups remained intact and appeared cytologically normal with no indication of cellular damage or injury.