Induction of ovulation in cyclic mares by administration of a synthetic prostaglandin, fenprostalene, during oestrus.
Fenprostalene (250 micrograms) or saline was given at 60 h after the onset of oestrus in alternate oestrous periods to 8 mares for 4 cycles. Onset of oestrus and stage of cycle were determined by daily teasing, palpation and ultrasonography until time of treatment when follicular development was monitored at 12-h intervals to confirm ovulation. Serum progesterone concentrations were monitored daily. The interval from treatment to ovulation was significantly decreased (41.25 vs 73.50 h; P = 0.001) as was the duration of oestrus (5.63 vs 6.88 days; P = 0.005). There was no significant difference in the duration of dioestrus (15.88 vs 15.75 days; P = 0.94). There were no significant differences between serum progesterone concentrations at onset of oestrus, at treatment or at examination before ovulation. Follicular size was not significantly different at onset of oestrus or before ovulation. There was no statistically significant difference in follicle size at the time of treatment when a possible horse effect was controlled for, although a significant difference (P less than 0.05) was seen when the horse effect was not taken into account. Clinically, 81% of treated mares had ovulated by 48 h after treatment compared to 31% of the control mares (chi 2; P less than 0.025). The results demonstrate that fenprostalene can effectively hasten time of ovulation in cyclic mares.
D000818:Animals; D004031:Diestrus / Q000187:drug effects; D004971:Estrus / Q000097:blood / Q000187:drug effects*; D005260:Female; D006736:Horses / Q000502:physiology*; D010062:Ovulation Induction / Q000662:veterinary*; D011374:Progesterone / Q000097:blood; D011461:Prostaglandins F, Synthetic / Q000494:pharmacology*
D011461:Prostaglandins F, Synthetic; D011374:Progesterone; C039153:fenprostalene