Short-term and long-term outcomes of ewes and their offspring after elective cesarean section

Abstract

Postoperative outcomes of animals that have undergone cesarean delivery have been reported previously; however, in most studies results were influenced by a combination of surgery per se and the preoperative condition of the animal, which was frequently impaired because of the presence of dystocia. To evaluate the effects of the cesarean section itself we conducted a matched cohort study comparing postpartum complications and future reproductive performance of 162 ewes subjected to elective cesarean section and 162 ewes that had an unassisted vaginal delivery. Survival and subsequent growth of their lambs were also compared. Effect of mode of delivery on weight gain was estimated using linear mixed models. Case ewes, which underwent surgery during the period from 1996 through 2004, and control ewes were from the flock at the Animal Production Experimental Centre, Norway. Two ewes (1.2%) that underwent cesarean section died; one developed peritonitis and the other experienced uterine prolapse and did not recover. Postoperatively, four ewes suffered from metritis, three suffered a wound infection, and four a delayed wound healing; all recovered after treatment. One of the ewes that delivered vaginally died 3 days after lambing. The incidences of fetal and postnatal deaths did not differ significantly between the cesarean and the vaginal delivery groups (fetal deaths, 3.5% and 3.1%, and postnatal deaths, 9.9% and 7.1%, respectively). Survival rates and weight gains of the lambs the subsequent months were similar for the two groups. Seventy percent of the ewes that had a cesarean section and 72% of those that had a vaginal delivery were bred the next season; conception rates were 89% and 90%, respectively. However, the ewes subjected to surgery the previous year gave birth to significantly fewer live-born lambs (mean, 1.64) than those that had had a vaginal delivery (1.93). The difference was the result of a reduced litter size and an increased number of fetal deaths in the former group. Birth weights of the live-born lambs the second year did not differ between the groups. In conclusion, severe short-term complications were rare among the ewes that underwent elective cesarean section. Survival and growth of their lambs and their conception rate the subsequent season did not differ from the corresponding outcomes of the ewes that delivered vaginally, but their fertility was reduced in the sense that they gave birth to fewer live-born lambs the following lambing season.