Evaluation of antibiotic usage during late gestation on pelvic organ prolapse incidence in sows

Lay Summary Sow mortality due to pelvic organ prolapse (POP) is a major concern affecting the U.S. swine industry. Despite widespread acknowledgement, strategies to mitigate POP are lacking. Therefore, this study examined the effect of bacitracin methylene disalicylate (BMD) supplementation on POP incidence in late-gestation sows across two commercial farms. BMD was administered via water at farm A, with 522 sows in the control group and 492 in the BMD group. At farm B, BMD was administered via on-farm mixing with feed, with 709 sows in the control group and 566 in the BMD group. Sows were administered BMD for approximately two weeks prior to farrowing and perineal score (PS) evaluations were conducted at gestation week 15 to determine presumed POP risk based on a 3-point perineal scoring system, with a PS of 1 (PS1) indicating low risk and a PS3 indicating high risk. Results indicated that BMD treatment did not affect PS or POP incidence at either farm. However, BMD-treated sows at high risk for POP (PS3) had fewer stillborn piglets compared to PS3 control sows. While BMD was ineffective in mitigating POP, the association with reduced stillbirths suggests further research is needed to explore potential benefits on improving piglet livability.