Fertility and uterine histology of postpartum mares treated with estradiol, antibiotics or uterine lavage

Abstract

In the first experiment twenty-four postpartum mares were infused on days two and three with either: (1) .2mg of estradiol benzoate (E(beta)) in a carrier 6 of 60 ml of physiologic saline, (2) 1 x 10('6) units of K Pencillin and 2.5 grams of Streptomycin (PS) in a carrier of 60 ml of physiologic saline, (3) a combination of 1 & 2 (E(beta) + PS), (4) 60 ml of physiologic saline only (control). On the seventh day postpartum mares were biopsied from the gravid and nongravid uterine horns. Histological samples were evaluated for epithelial cell height, edema and inflammation. Intrauterine infusion did not affect either conception rates, abortion rates or any histological variables measured. There were no significant relationships between any histological variables and conception or abortion rates. In the second experiment twenty-three mares were infused on days two and three postpartum. Mares in treatments one and two received either: (1) two uterine lavages with two liters of warm hypertonic saline, or (2) intrauterine infusion with 500 mg of gentamycin sulfate. Mares in the third treatment group were not treated and served as controls. Treatment had no significant effect on either conception rates or abortion rates. Treatments used in the second experiment had no effect on epithelial cell height or edema at day seven postpartum. Uterine lavage with hypertonic saline resulted in significantly less inflammation in the gravid and non-gravid uterine horns. Inflammation in the non-gravid horn was related to an increase in abortion. Inflammation of the endometrium did not affect conception during foal heat, however, mares which conceived during foal heat but later aborted had higher inflammation scores in both the gravid and non-gravid uterine horns. Overall means for histological variables measured were similar in the gravid and non-gravid uterine horns, indicating that uterine involution measured either grossly or histologically occurred at similar rates for each uterine horn. Mares which ovulated 14 or more days after foaling had higher foal heat conception rates than those which ovulated earlier. Finally, intrauterine infusion of estradiol, penicillin and streptomycin or gentamycin had no effect on uterine histology, conception rate or foaling rates and were of no benefit to reproductive performance in this study.