Protracted induction of parturition enhances placental maturation, but does not influence incidence of placental retention in cows

Abstract

As the etiopathology of retained placenta is still not resolved in cattle, we compared the effects of protracted induction of parturition (PIP) and conventional induction of parturition (SIP) on placental maturation and the occurrence of retained placenta. PIP was induced in 13 cows by administration of 1.3 mg dexamethasone im twice daily between Days 268 and 273 of gestation and 40 mg dexamethasone im on Day 274 of gestation. For SIP, 10 cows received a single injection of 40 mg dexamethasone on Day 274 of gestation. A third group (SPON, n = 11) served as a nontreated control group. Within 2 hours after birth, two placentomes were extracted from the uterus and used for assessment of placental maturation by histology and immunohistochemistry. Incidence of retained placenta was lower (P < 0.05) in group SPON (9%) compared with groups PIP (54%) and SIP (70%). Staining with Masson's trichrome and pan-cytokeratin indicated a higher degree of atrophy and flatness of the maternal crypt epithelium in cows with physiological release of fetal membranes (REL) compared with cows with retained placentae (RET). Staining with anti-caspase-3 ratified the observations as more apoptotic cells were detected in groups SPON and PIP compared with group SIP; however, data were not statistically significant. Additionally, the expressions of the potent vasodilators endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) were evaluated. Both eNOS and iNOS were only expressed in chorionic tissue. Endothelin-1 (ET-1), a major vasoconstrictor, showed positive staining in maternal crypt epithelium and in chorionic epithelium. No differences were found for iNOS and eNOS and ET-1, neither among the experimental groups nor between RET and REL cows. These findings indicate that a PIP results in increased placental maturation, but does not influence the incidence of placental retention in cows. The expression of vasoactive substances does not seem to be related to the placental separation process.

Repeated low doses of dexamethasone as a pretreatment for induction of parturition in Simmental cows

“…It is well known that many factors are related to PR; however, the mechanisms underlying PR and the induction of parturition by corticosteroids are not well understood [46]. The differences between the current findings and the results of Hartmann et al might be due to the timing of induction and gestation lengths [13]. Some researchers have reported that gestation length was directly associated with the risk of developing PR [39,47,48].…”

“…Although much effort has been focused on decreasing the rate of this complication [41][42][43], better results were obtained by previous studies, including treatment with long-acting corticosteroids [41,44,45]. Nevertheless, there are legal restrictions for the use of long-acting corticosteroids in food-producing animals in Europe [13,38] and induction using longacting corticosteroids has wide variability in response to treatment and lower predictability in terms of calving time [8,41]. Hartmann et al evaluated the use of low dosages of short-acting corticosteroids for the induction of parturition and showed that this alternative approach had a positive effect on the progress of placental maturation, but it did not have a positive effect on placental separation [13].…”

“…Nevertheless, there are legal restrictions for the use of long-acting corticosteroids in food-producing animals in Europe [13,38] and induction using longacting corticosteroids has wide variability in response to treatment and lower predictability in terms of calving time [8,41]. Hartmann et al evaluated the use of low dosages of short-acting corticosteroids for the induction of parturition and showed that this alternative approach had a positive effect on the progress of placental maturation, but it did not have a positive effect on placental separation [13]. The authors obtained a numerically lower rate of PR in cows subjected to protracted induction (54%) when compared to conventionally induced cows (70%).…”

“…Similarly, Zerbe et al [12] proposed a regime consisting of repeated low doses of corticosteroid therapy to mimic the physiological process for premature calving in cows. Later, a similar approach was adapted by Hartmann et al [13] for the induction of parturition in cows. The authors proposed the protracted induction of parturition, including repeated low doses of dexamethasone for several days followed by a final high dose as an alternative protocol.…”

Comparison of Two Different Protocols for Induction of Parturition in Heifers with or without Estradiol Benzoate

“…Hartmann et al [20] reported that performing protracted induction of parturition by administration of dexamethasone twice daily between day 268th and 273rd of gestation results in increased placental maturation, but does not influence the incidence of placental retention in cows. Average incidence of fetal membranes retention for normal dairy cows range from 4%-18% [21].…”