Relaxatory Effect of Prostaglandin E2 on Circular Smooth Muscle Isolated from the Equine Oviductal Isthmus1

Equine Veterinary Journal

Morris

et al. 2010

Summary Reasons for performing study: Mares are occasionally encountered that consistently fail to conceive when inseminated, naturally or artificially, with fertile stallion semen in the absence of any identifiable pathology of either the structure or function of their reproductive tract. Hypothesis: Temporary blockage of the oviducts by accumulations of naturally occurring oviducal masses may be preventing oviducal transport of the embryo to the uterus. Methods: Mares, with known reproductive histories, that had exhibited inexplicable failure of conception were treated by laparoscopically guided administration of PGE2‐laced triacetin gel directly onto the surface of their oviducts. Results: Fifteen mares age 10–21 years that had exhibited inexplicable failure of conception during 1–4 years were treated, of which 14 (93%) conceived within the same or subsequent breeding season. Conclusions: The high success rate of this treatment supports the tentative diagnosis of oviducal obstruction in these mares and indicates that blockage of the mare's oviducts may occur in the form of a moveable accumulation of debris rather than from permanent fibrous adhesions resulting from salpingitis. Potential relevance: This laparoscopic application of PGE2 to the oviducts constitutes a sound and practical method of restoring fertility in mares suffering oviducal obstruction and further studies involving the procedure are warranted.

Section: Introductionmentioning

confidence: 90%

Laparoscopic application of PGE2 to re-establish oviducal patency and fertility in infertile mares: a preliminary study

Allen

Equine Veterinary Journal

Morris

et al. 2010

“…A more recent application has been to use laparoscopy to apply a prostaglandin E 2 gel preparation, designed to soften and dilate the cervix in pregnant women to facilitate labour, to the whole length of the equine oviduct (Fig b; ) to presumptively unblock the oviducts of infertile mares. Application of the gel to the oviduct induces relaxation of the circular and contraction of the longitudinal smooth muscle fibres in the wall of the oviduct, thereby mimicking the PGE 2 normally released by the equine embryo to “drive itself” down the oviduct and through the very tight uterotubal junction to enter the uterus on Day 6–6.5 after ovulation . The supraphysiological dose of the drug is believed to clear accumulations of oviducal masses (Fig c) and allows the fertilised oocyte to pass through the oviduct.…”

Section: Videoendoscopy and Laparoscopymentioning

confidence: 99%

Half a century of equine reproduction research and application: A veterinarytour de force

Allen

Equine Veterinary Journal

2017

SummaryOver the past 50 years, per season pregnancy rate in Thoroughbred mares have risen from 70 to >90% and foaling rates from 55 to >80%. Some of the significant pharmacological treatments and diagnostic methods which have driven this marked improvement in breeding efficiency are reviewed. They include the application of artificial lighting to hasten the onset of ovulatory oestrous cyclicity in early Spring, rapid steroid hormone assays to aid in determining the stage and normality of the mare's cycle, prostaglandin analogues, synthetic progestagens and Gonadotrophin-releasing Hormone (GnRH) analogues to better control and manipulate her cycle to good effect, transrectal ultrasound scanning to monitor follicle growth, endometrial architecture and ovulation and to allow accurate, early pregnancy diagnosis thereby enabling successful ablation of one of twin conceptuses. Also, flexible videoendoscopy to monitor physiological and pathological changes in the uterine endometrium and rigid laparoscopy to apply prostaglandin to the oviducts to dislodge and clear suspected blockages of them to restore fertility. The outbreak of Contagious Equine Metritis in Newmarket in the spring of 1977 and the swabbing-related changes to mare and stallion management, plus the improved veterinary hygiene methods, which followed are also recounted. The past half century has witnessed many technical and therapeutic advances that have enhanced tremendously the diagnostic and treatment capabilities of studfarm veterinary surgeons. They, in turn, have improved greatly the efficiency of breeding Thoroughbreds and other types of horses.

“…Such oviducal masses are not infrequently observed in uterine flushes undertaken to retrieve an embryo for transfer ( Fig 2) and their presence in the flushings invariably indicates that an embryo will also be found. Like unfertilised oocytes, oviducal masses can only pass down the oviduct when PGE 2 secreted by the embryo causes relaxation of the circular and contraction of the longitudinal smooth muscles in the wall of the oviduct (Rodriguez-Martinez and Einarsson 1985;Troedsson et al 1995;Weber et al 1995).…”

Section: The Oviductmentioning

confidence: 99%

The uterus and early pregnancy failure in the mare

Equine Veterinary Education

2017

Summary The environment the equine conceptus finds itself in when it arrives in the uterus some 6 days after ovulation will determine if it will thrive or die. The uterus will be its home for approximately the next 11 months and as such it needs to both coordinate the growth of the placenta and ensure there is enough nourishment passing to this organ for the fetus to develop normally. The trophoblast, endometrium, maternal ovaries and, later in pregnancy, the fetal gonads, all play roles in the hormonal changes that orchestrate these events. Although failures of these processes later in pregnancy can have catastrophic effects for the fetus, it is in early gestation that the foundations for a successful pregnancy are laid. This paper therefore concentrates on some of the noninfectious influences the uterus may have on survival of the young conceptus.