Exogenous oxytocin dilates the cervix in ewes

Abstract

Cervical anatomy in ewes usually prevents nonsurgical, intrauterine AI and transcervical embryo transfer (ET), which limits their commercial use in sheep. This study was conducted to determine whether oxytocin would dilate the cervix in ewes and permit passage of a stainless steel rod into the uterus. In Exp. 1, at 44 and 52 h after removal of progestogenated pessaries, ewes were injected i.v. with 0 (saline), 200, 400, or 600 USP units of oxytocin. Immediately before and after treatments, stainless steel rods were used to evaluate cervical dilation and determine whether the uterus could be entered. A rod could not be passed through the cervix and into the uterus in any of the saline-treated ewes. All doses of oxytocin given at 44 and 52 h after pessary removal dilated the cervix and permitted easy passage of a rod into the uterus. At both 44 and 52 h, a stainless steel rod was passed into the uterus in 33 of 43 (77%) of the oxytocin-treated ewes. In 93% (40/43) of these ewes, a rod could be passed into the uterus during either the 44-h or during the 52-h attempt. In Exp. 2, on d 9 after pessary removal, ewes were injected i.v. with oxytocin (400 USP units) at 6 or 12 h after i.v. estradiol-17 beta (0, 100, or 200 micrograms). Cervical dilation was evaluated as in Exp. 1. Dose of estradiol x time of oxytocin affected (P less than .01) the proportion of ewes in which a rod could be passed transcervically into the uterus.(ABSTRACT TRUNCATED AT 250 WORDS)

A Review of Advances in Artificial Insemination (AI) and Embryo Transfer (ET) in Sheep, with the Special Reference to Hormonal Induction of Cervical Dilation and its Implications for Controlled Animal Reproduction and Surgical Techniques

“…Khalifa et al, [56] demonstrated that a stainless steel rod could be passed through the cervix into the uterus in 77% of ewes treated with 200, 400 or 600 USP of exogenous oxytocin injected i.v. ; the same rod could not be passed transcervically into the uterus of any saline-treated animals.…”

Cervical dilation and improvement of reproductive performance in fat-tailed ewes via cervical dilator treatments

“…This answer may be explained by effects of oxytocin that initiates collagenolytic enzyme process resulting in cervical dilation [19]. Previous studies showed that E 2 +OT or only OT [13,[20][21][22] caused cervical dilation in ewes. It has been proven that 400 IU OT led to dilation of cervix, but the injection of this amount of hormone right before the insemination may have some problems.…”

“…In recent years, hormonal strategy has been proposed to improve the efficacy of AI. Oxytocin and prostaglandin E (PGE) are effective hormones on cervix dilation [8,13,14]. Oxytocin and E 2 have no effects on luteal phase and have minimum injury when pipette is crossing the cervix during AI [8].…”

Mechanical and Pharmacologic Applications of Artificial Insemination in Ewes

“…Oxytocin treatment caused relaxation of cervix and uterine catheter through the cervix have demonstrated that reduced the difficulty of the transition (Khalifa et al, 1992;Sayre and Lewis, 1996). The effect of oxytocin as a cervical dilator is different on the reproductive outcome in ewe.…”