PROPHYLAXIS OF RESPIRATORY-DISTRESS SYNDROME IN PREMATURE CALVES BY ADMINISTRATION OF DEXAMETHASONE OR A PROSTAGLANDIN-F2-ALPHA ANALOG TO THEIR DAMS BEFORE PARTURITION

Objective-To investigate effects of preterm induction of calving by ad ministration of flumethasone and dinoprost on the lecithin-to-sphingom yelin ratio in amniotic fluid and on neonatal respiratory distress aft er birth. Animals-45 dairy cows and their newborn calves. Procedure-Am niotic fluid from 45 cows was obtained and tested between days 258 and 270 of gestation. Cows were then given flumethasone (10 mg; n = 15), dinoprost (25 mg; n = 15), or saline solution (n = 15). Thirty hours l ater, left flank cesarean section was performed, amniotic fluid was co llected, and the calf was delivered. Blood for determination of proges terone was withdrawn at amniotic fluid sample collections and before i nduction of calving. Blood for analysis of pH and base deficit was col lected from calves during cesarean section and repeatedly after birth. Phospholipids in amniotic fluid were measured by thin-layer chromatog raphy, and progesterone was determined by radioimmunoassay. Base defic it and pH were measured, using a blood gas analyzer. Results-Before tr eatments, a corpus luteum was present in all cows and the lecithin-to- sphingomyelin ratio in amniotic fluid did not differ between groups, T hirty hours after injections of flumethasone and dinoprost, progestero ne concentration had decreased (P < 0.05) and the lecithin-to-sphingom yelin ratio was significantly (P < 0.05) higher than values in control s. In calves delivered after flumethasone or dinoprost treatments, the degree of acidosis was significantly (P < 0.05) less than that in con trols. Conclusions-Flumethasone and dinoprost, given to pregnant cows, accelerate fetal lung maturation and improve respiratory function aft er birth.