Effects of administration of prostagrandin F(2)(alpha)-analogue fenprostalene on canine corpus luteum and subsequent recurrence of estrus and fecundity

The effects of the long-acting prostagrandin F(2)(alpha)-analogue fenprostalene were investigated. Twenty-three female beagles (24 cases) 1-6 years of age were divided into 6 groups, and a dose of 5-150 microg/head of fenprostalene was subcutaneously administered at 25 days after ovulation to investigate its effects based on peripheral blood progesterone (P(4)) levels. The dogs were also examined for shortening of their estrous cycle after administration and fecundity after the recurrence of estrus. The results showed that the administration of 50 microg/head of fenprostalene or more reduced the levels of peripheral blood P(4) to about 1 ng/ml 2 days after administration, indicating early regression of the corpus luteum, and that the administration of these doses shortened the time to the subsequent estrus by a mean of about 80 days, and that conception rates were normal if estrus recurred about 2 months after fenprostalene administration or later.