Effect of dexamethasone on the estrous cycle length in Black Bengal goats (Capra hircus )

In an experiment to examine the relationships between adrenals and reproductive cycle, 10 mg dexamethasone (a synthetic glucocorticoid) were injected intramuscularly twice daily for 10 d to four Black Bengal goats, beginning on Day 11 of the synchronized estrous cycle. The extended length of the sexual cycle was monitored by the clinical signs of anestrus. Laparotomy was performed to examine the status of the ovary of an 8, 9, 10 and 8 d extended cycle, respectively. The length of the next cycle was normal. Endogenous cortisol values were suppressed for 11, 13, 20 and 24 d, respectively. It is thought that dexamethasone caused prolonged luteal function either by the suppression of prostaglandin F(2)alpha synthesis or by the suppression of pituitary stimulation of follicular growth.