The Effect of Prostaglandin E₂ on the Cervices of Dioestrous and Prepartum Mares

Abstract

ContentsTwo experiments were conducted in order to determine the clinical effects of intracervical application of prostaglandin E2 (PGE2) in mares. In Experiment 1, PGE2 or placebo tablets were introduced into the cervical canal of &oestrous mares. PGE2 induced SiBtllficant cervical softening and oedema within 30-90 min after application. Uterine tone increased significantly within a few min after PGE2 treatment and remained elevated for 60-90 min. PGE2 treatment had no effect on plasma progesterone concentrations. In Experiment 2, 19 mares were each subjected to one of 3 treatments: Group A (n=5) received 10 IU oxytocin intravenously on the first day after day 325 of gestation when clinical criteria of "readiness for birth" had been satisfied. Gestational age was 328-349 days. Mares in Group B (n=6) and Group C (n=S) were treated on the first convenient day after day 325 of gestation, but before their cervices had started to &late. Group B mares received 4 intracervical applications of PGE2 at 30 min intervals. Group C mares 'were given 10 IU oxytocin intravenously, 30 min after the second PGE2 application. Mares of Groups B and C were treated between days 327 and 338 of gestation. PGE2 treatment alone failed to consistently induce parturition and mares foaled between 14 h and 8 days after treatment. Complete cervical dilation was, however, induced in all PGE2 treated mares and was maintained until parturition. Group C mares (PGE2 followed by oxytocin) foaled 16-1 15 min after oxytocin treatment which was not different from Group A. Premature placental separation occurred in 1 of 5 mares in Group A and in 3 of 8 mares in Group C. All 5 foals in Group A were healthy and survived. Two of 6 and 3 of 8 foals in Groups B and C, respectively, developed neonatal dlsease and died between 1 and 26 days after birth. Although PGE2 induced rapid and complete cervical dilatation in near-term pregnant mares, it failed to induce parturition and when used in combination with oxytocin, foal health and survival were poor. It is concluded that PGE2 will be of little value as an adjunct to routine equine partus induction, because foal survival will be poor if inductions are performed at a stage when the mare's cervix is not adequately relaxed for induction of parturition using oxytocin alone. U.S

Clinical observations on the course of oxytocinor prostaglandin E2/oxytocin-induced parturition in mares

“…This effect could be observed despite lower doses of PGE2 and shorter interval between PGE2 insertion and oxytocin treatment than in the other studies (Volkmann et al 1995, Rigby et al 1998. Statistically insignificant OTES, OTCA and OTDE might be partly attributed to the low power of statistical analysis which resulted from small group size as well as to the protocol applied in which additional oxytocin doses were used if only progress in parturition was unsatisfactory.…”

“…In our study no negative influence of PGE2 on newborns condition could be observed. One of the reason of this difference in results when comparing to Volkmann's et al (1995), could be the fact that we induced parturitions in later pregnancies, what could be crucial for final foal maturation.…”

“…Thus far two studies have evaluated efficacy and safety of PGE2/oxytocin treatment in inducing parturition in mares. Volkmann et al (1995) observed reduced foal survival after PGE2 treatment and found this medicine of little value as adjunct to the routine treatment with oxytocin. On the contrary, Rigby et al (1998) obtained satisfactory results in terms of shortening delivery and promoting foal vigor.…”

Effects of Topical Application of Misoprostol on Cervical Relaxation in Mares

“…Volkmann et al. () previously concluded that PGE 2 suppositories in the cervical canal of dioestrous mares resulted in fast and complete cervical softening. In addition, the authors reported that within 30 min of the application of the first PGE 2 tablet only the tissues in the immediate vicinity of the suppositories had responded to the drug, as determined by manual evaluation of the cervical canal (Volkmann et al.…”

“…In addition, the authors reported that within 30 min of the application of the first PGE 2 tablet only the tissues in the immediate vicinity of the suppositories had responded to the drug, as determined by manual evaluation of the cervical canal (Volkmann et al. ). The high expense of PGE 2 and the fact that the synthetic PGE 1 analogue misoprostol became the drug of choice in human obstetrics prompted clinicians to look at the effects of PGE 1 on cervical relaxation in the mare.…”