Development of Timed Release Vaginal Mucosal Cloprostenol for Farrowing Management in Sows

Background/Objectives: Controlling the timing of farrowing to occur during working hours presents an opportunity to improve supervision and reduce piglet neonatal mortality. However, the use of non-therapeutic injectable drugs is often limited in commercial swine production. This study aimed to develop a cloprostenol vaginal mucosal delivery system for induction of farrowing. To achieve this, two vaginal tablets containing cloprostenol were formulated for simultaneous insertion: an immediate-release (IR) tablet and a delayed release (DR) tablet, the latter designed for a 6 h delay before release. Methods: In vitro release studies demonstrated that the IR tablet released 100% of the drug within 5 min, while the DR tablet, initiated release after four hours and achieved approximately 80% release at six hours, aligning with the targeted release profile. To evaluate the efficacy of the optimized formulations, an in vivo study was conducted using 121 mixed parity Landrace × Large White sows that were assigned to one of four treatments, control (n = 23) received no treatment; IM (n = 26) received 185 µg of cloprostenol via intramuscular injection; IR (n = 36) received a 100 µg IR tablet by vaginal deposition; and IR + DR (n = 36) received both IR and DR tablets by vaginal deposition, to simulate split-dose delivery. Results: Control sows experienced longer (P < 0.001) intervals to farrowing compared to those receiving cloprostenol treatments. Additionally, differences (P < 0.05) were observed in interval from treatment to farrowing time among the treatments, with the interval for IM sows being shorter than for IR (P < 0.001) and IR + DR (P = 0.001) sows. Conclusions: These findings confirm that the vaginal route offers an alternative, non-invasive, method for farrowing induction in sows, facilitating farrowing supervision during working hours and potentially reducing piglet mortality.