Dose rate, time of injection and litter size effects on dexamethasone‐induced parturition in Border Leicester x Merino ewes

Analyses of parental and seasonal influences on the synchrony of dexamethasone-induced lambing and lamb characteristics

“…Dexamethasone has been confirmed to be most effective at inducing parturition at a dose rate of 8-16 mg per ewe injected at 1-3 days before full term (Edey et al, 1985). In the present study, a single dose of 20 mg dexamethasone per ewe was administered on day 140 of pregnancy (Adams and Wagner, 1970; http://www.merckvetmanual.com/mvm/index.jsp?cfile= htm/bc/80803.htm).…”

“…It has been found that when parturition is induced close to full term (∼144d), ewes tend to have a shorter interval between induction and parturition, and exhibit a tighter synchronization of lambing (Edey et al, 1985). Dexamethasone has been confirmed to be most effective at inducing parturition at a dose rate of 8-16 mg per ewe injected at 1-3 days before full term (Edey et al, 1985).…”

“…Dexamethasone is an exogenous corticosteroid used to induce parturition by mimicking the natural fetal cortisol influx into maternal circulation (Ingoldby and Jackson, 2001). A single dose of 10-20 mg of dexamethasone given intramuscularly (Edey et al, 1985;Ingoldby and Jackson, 2001;Rawlings and Bartlewski, 2007;Menzies, 2007) is the common procedure to induce labour and can be given as early as day 137 of a 144-149-day gestation period (Kastelic et al, 1996;Ingoldby and Jackson, 2001). However, administration of dexamethasone before day 142 is generally avoided to promote increased fetal viability (Rawlings and Bartlewski, 2007;Menzies, 2007).…”