Induction of parturition in bitches with minimal side effects by two injections of a low dose of fenprostalene, a prostaglandin F2alpha analogue, and pretreatment with prifinium bromide.

An experiment using 16 Beagle bitches (aged 11 months to 6 years and 2 months) in their 56th to 58th day of pregnancy was carried out to investigate the effects of two injections of a low dose of fenprostalene, a long-acting prostaglandin F2alpha analogue, and pretreatment with prifinium bromide, a parasympathetic nerve blocking agent, on the induction of parturition and severity of side effects. The bitches were divided into three treatment groups: one injection of 5 microg/kg of fenprostalene (group I, n=5); one injection of 7.5 mg/head of prifinium bromide followed by one injection of 5 microg/kg of fenprostalene at 5 min after prifinium bromide injection (group II, n=6); and one injection of 7.5 mg/head of prifinium bromide followed by two injections of 2.5 microg/kg of fenprostalene, one injection at 5 min after prifinium bromide injection and the next at 1 hr after the fenprostalene first injection (group III, n=5). Following the injection of fenprostalene, side effects such as salivation, vomiting, colic symptoms, and watery diarrhea occurred most frequently (80-100% of cases) in group I bitches. Apart from colic symptoms, no side effects were observed in group III bitches. Group III bitches also showed the smallest increase in plasma cortisol concentration. No significant difference in the time to initiation of parturition was found between the three groups. The one-week survival rate of newborn puppies was highest in group III. The results showed that pretreatment with prifinium bromide and two injections of 2.5 microg/kg of fenprostalene can alleviate side effects following fenprostalene administration and have no adverse effect on the survival of newborn puppies, indicating that this method is a reliable and safe way of inducing parturition in bitches.