Peripheral Plasma Levels of Oxytocin and Vasopressin in the Mare During Parturition

Allen, W. Edward; Chard, Tim; Forsling, Mary L.

doi:10.1677/joe.0.0570175

Cited by 46 publications

(27 citation statements)

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Section: Discussionsupporting

confidence: 92%

“…We cannot claim that the blood collection method did not cause any stress on the mares. However, the hormonal changes (i.e., an increase in the circulating OT and PGFM concentrations) during foaling in the present research were mostly in agreement with previous studies [1,8,15,20,21].In this study, although we could not collect a large number of blood samples before foaling, it seemed that large differences existed among the mares in the levels of circulating OT at foaling. Moreover, the differences were still detectable immediately after foaling.…”

supporting

confidence: 93%

“…In this study, however, the number of mares in which blood was sampled before foaling was limited. However, an increase in the circulating OT and PGFM concentrations close to foaling in the heavy draft mares was in agreement with previous findings in other breeds of horse [1,8,15,20,21].OT is a neurohormone under the control of the central nervous system and therefore could be a factor in the mare's ability to determine the time of parturition accordingly to the presence of a favorable environment [7,8,19]. It is expected that the relationship between the peaks of the OT or PGFM concentrations and rupture of the membrane or delivery of the foal is influenced by the size of the foal or environmental stressors.…”

supporting

confidence: 92%

“…OT is considered the final hormone in the maternal cascade leading to parturition [19]. The OT concentration increases rapidly during the second stage of labor in mares [1,8,20]. In a report in which the OT in pituitary effluent collected from the intercavernal sinus was measured [21], the OT concentration increased markedly from 1 to 11 min after rupture of the chorioallantois, and OT secretion continued during delivery of the foal.…”

Section: Discussionmentioning

confidence: 99%

“…Manual removal of the placenta led to a decrease in subsequent fertility [9]. The level of circulating oxytocin (OT) rises rapidly in the 2nd stage of delivery in mares [1,8, 24]. Moreover, it is known that OT secretion helps discharge milk from the mammary glands [5,21].…”

mentioning

confidence: 99%

See 4 more Smart Citations

Relationship between Peripartal Plasma Oxytocin and Prostaglandin F2.ALPHA. Metabolite and Placental Expulsion Time in Heavy Draft Mares

Ishii

Kobayashi

Acosta

et al. 2008

Journal of Reproduction and Development

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Abstract. The aim of this study was to clarify the relationship between circulating oxytocin (OT) and PGF2α metabolite (PGFM) in mares at the third stage of labor and placental expulsion time in order to investigate a cause of retained placenta of which the incidence increase in a heavy draft mare. Blood was sampled every 5 min from foaling to expulsion of the placenta in 18 heavy draft mares to evaluate circulating OT and PGFM. The relationships between OT and PGFM concentration and recorded placental expulsion times were investigated. The results were as follows (1) The highest level of OT concentration was observed close to foaling in 15 mares. (2) The OT concentrations close to foaling were variable with a large difference from the lowest concentration, 22.1 pg/ml, to the highest concentration, 209.3 pg/ ml. (3) The highest level of PGFM was observed close to foaling in 17 mares. (4) During the 60 min following foaling, the OT concentrations of the mares (n=11) that had a shorter placental expulsion time (i.e., <1 h), were significantly higher than those of the mares (n=7) that had a longer placental expulsion time (i.e., >1 h; P<0.05). Collectively, the OT concentration immediately after foaling is negatively related to the placental expulsion time. Deficiency of OT secretion at foaling have should be considered as one of the causes of retained placenta in heavy draft mares. Key words: Heavy draft mare, Oxytocin, 15-keto-dihydro prostaglandin F2α (PGFM), Placental expulsion (J. Reprod. Dev. 54: [270][271][272][273][274] 2008) ecently, the heavy draft horses of Japan have increased in size and become one of the largest breeds in the world. Retained placenta is occurring more frequently in heavy draft mares due to corpulence with lack of exercise because they are not used for work. A prolonged retained placenta in a mare causes a puerperal infectious disease and laminitis, and it may also cause death. Several causes of retained placenta, such as uterine inertia, placentitis, chill stress and hormone imbalance, have been considered [10,17,20]. Extension of the placental expulsion time reduces the subsequent conception rate in mares [9]. Although the conception rate of foaling heat in mares whose placental expulsion time was less than 1 hour was 66%, the conception rate of mares in which the placental expulsion time exceeded 4 h fell to 51.7% [9]. Manual removal of the placenta led to a decrease in subsequent fertility [9]. The level of circulating oxytocin (OT) rises rapidly in the 2nd stage of delivery in mares [1,8, 24]. Moreover, it is known that OT secretion helps discharge milk from the mammary glands [5,21]. Prostaglandin F2α (PG) might play a role in contraction of the myometrium at delivery. The circulating PG concentration in mares is determined generally by measurement of 15-keto-dihydro PGF2α (PGFM) [2,8,16]. The PGFM concentration, which is PG and its metabolic product, rises during the last stage of pregnancy or at the time of delivery [2,8,16,18,20,21]. According to detailed observations throu...

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Section: Discussionsupporting

confidence: 92%

supporting

confidence: 93%

supporting

confidence: 92%