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.