Evaluation of vaginal ampicillin administration in late gestation sows on pelvic organ prolapse in relation to perineal score and litter characteristics

Abstract Within the last decade, increased sow mortality resulting from pelvic organ prolapse (POP) has become a growing concern in the swine industry. Despite being widely acknowledged as a sow welfare and production issue, mitigation strategies are scarce. Previous studies have demonstrated differences in the vaginal microbiome are associated with risk for POP during late gestation, representing a potential target for prevention strategies. The objective of the current study was to evaluate effects of vaginal infusion of ampicillin during late gestation on POP incidence. To accomplish this, the hypothesis that vaginal infusions of antibiotics would reduce POP risk during late gestation was tested. Ampicillin was infused into the vagina at two timepoints during late gestation. The first dose (10 mL at 200 mg/mL) was administered at gestational day 96 ± 0.09 followed by a second, equivalent dose at gestational day 112 ± 0.10. Sows were randomly assigned to treated (TRT; n = 824) and non-treated (CON; n = 739) groups based on gestation pen. At gestational days 107-116, sows (n = 1,076) were evaluated for POP risk using a three-point perineal scoring system. Briefly, a perineal score (PS) of 1 (PS1) presumes little to no risk of POP, and a PS of 3 (PS3) presumes high risk of POP. From the 1,076 sows assigned a PS, 46.5%, 49.7% and 3.8% of sows were assigned PS1, PS2, or PS3, respectively. Ampicillin treatment had no effect on PS (P = 0.20), with 45.6%, 51.6% and 2.8% of CON sows and 47.2%, 48.1% and 4.7% of TRT sows scoring a PS1, PS2, or PS3, respectively. Additionally, treatment did not affect (P = 0.74) POP incidence, with 4.5% of CON sows and 4.7% of TRT sows subsequently experiencing POP. Ampicillin treatment did not affect (P ≥ 0.54) litter characteristics. However, there was an effect of PS on litter characteristics observed with total born and stillborn piglets (P < 0.01), and a tendency for a difference in liveborn piglets (P = 0.09) between sows scored PS3 and PS1. Sows assigned a PS3 had fewer piglets born alive, presumably due to the increased number of stillborn piglets. Additionally, PS3 sows had 1 more total born on average within their litters compared to PS1 assigned sows (P < 0.01). In conclusion, vaginal infusion of ampicillin had no effect on PS, POP incidence, or litter characteristics, but PS did have an effect on the number of piglets born alive.