Effects of intrauterine infusion of Escherichia coli endotoxin in anestrous and steroid treated pony mares.

This study was conducted to determine if Escherichia coli endotoxin was absorbed from the equine uterus and if exogenous progesterone and estrogen affected the absorption of intrauterine endotoxin. Six mature anestrous pony mares were used in three consecutive crossover experiments (Periods) with a 14 day recovery between each period. Mares were randomly assigned to one of two treatment groups (three mares per group) and received an intrauterine infusion of either saline or endotoxin. Treatment groups were reversed and readministered after 14 days completing a crossover design (Period 1). During Periods 2 and 3 the mares were treated with estradiol-17beta (4.0 mg/day) or progesterone (400 mg/day), respectively, for 5 days prior to receiving intrauterine infusions. On the day of intrauterine infusions rectal temperatures and jugular blood samples were obtained at 30 to 60 minute intervals. Blood samples were analyzed for total white blood cell counts and by Limulus Amebocyte Lysate Assays. There were no significant alterations in the observed parameters among the various treatment groups. These results indicated that intrauterine E. coli endotoxin was not absorbed from the uterus of anestrous pony mares in large enough amounts to produce a morbid condition and that prior exposure to exogenous progesterone or estradiol-17beta did not affect the absorption of endotoxin from the equine uterus.