Control of prostaglandin-induced parturition in sows by injection of the beta-adrenergic blocking agent carazolol or carazolol and oxytocin.

Although parturition commonly is induced in swine with prostaglandin F2 alpha or one of its analogs, variation in response to the treatment is large. The purpose of this investigation was to more precisely terminate parturition. Two experiments were conducted. Sows all received prostaglandin analog followed, 20 h later, by different doses of the beta-adrenergic blocking agent carazolol and(or) oxytocin. Treatment with 3 mg of carazolol alone caused parturition to commence within 2.6 +/- .23 (SEM) h after injection. Parturition was complete in 2.0 +/- .13 h and proceeded smoothly without the necessity of manual assistance. Adding 2.5 I.U. of oxytocin to the 3 mg of carazolol speeded the onset of labor (1.7 +/- .17 h). However, in some cases parturition was interrupted and the time passing between the birth of the first and the last piglet was prolonged to 2.5 +/- .28 h. We conclude that by applying carazolol 20 h after a prostaglandin analog, parturition in swine may be terminated very effectively.