Efeito de diferentes tipos de estrógeno e regimes de tratamento sobre o edema endometrial em éguas em anestro

Abstract

The use of acyclic mares as recipients is an alternative that optimizes embryo transfer programs, enabling the generation of a greater number of foals per year. This is only possible with the application of hormonal protocols that use estrogens and progestins in these mares, simulating an uterine environment that resembles cyclic recipients. Several studies have shown the effectiveness of using these exogenous hormones in noncycling mares in order to use them as recipients, some studies even reporting higher pregnancy rates in acyclic mares when compared to cyclic mares. As a result, these protocols have been widely used, with several variations regarding the regimen used, time of exposure to the hormone, type of hormone used, doses, routes of administration, among others. Therefore, the objective of the present study was to evaluate the effect of different treatment regimens using estradiol benzoate, estradiol cypionate and estradiol-17β on the intensity and duration of uterine edema in acyclic mares, in order to bring more information that can improve the use of hormonal protocols in acyclic mares, optimizing embryo transfer programs. For this porpuse, 16 acyclic mares were used, separated into 4 groups that were treated with different estrogen regimens for 3 days. The ECP, BE and 17βE-20mg groups received doses of 10mg, 6mg and 4mg of estradiol cypionate, estradiol benzoate and 17β respectively, whereas group 17βE-40mg was treated with doses of 10mg, 20mg and 10mg of estradiol-17β. Transrectal palpations and ultrassonographic exams were performed on all mares daily, starting on the day of the first hormonal application (D0) and extending for until 10 days or until the disappearance of uterine edema. There was no difference in the intensity and duration of endometrial edema between groups BE, EC and 17βE-40mg. The group 17βE-20mg presented less lasting edema, although a statistical difference in the edema intensity from D4 to D7 was pointed out only when compared to the 17βE-40mg group. It was concluded that the BE, EC and 17βE-40mg groups had similar edema intensity and duration, while the 17βE-20mg group had less lasting and less intense edema when compared to the 17βE-40mg group.