Gonadotrophin in the induction of estrus in bitches

Abstract

The present study aimed to investigate the efficiency of gonadotrophins to induce estrus in bitches, which was monitored using vaginal cytology, serum progesterone and ovarium morphology. Nine bitches of different breeds ageing one to four years were used. The protocol of estrus induction consisted of daily administration of eCG (equine chorionic gonadotrophin) at dose of 30 UI/kg, once daily, for nine days, followed by a single administration of hCG (human chorionic gonadotrophin) at dose of 500 UI/animal on the tenth day. Vaginal cytology was done every two days. On the 12nd day after the beginning of this protocol, ovariohysterectomy was performed to collect the ovaries; serum was collected for progesterone concentration. Every animal showed cytological alterations by the progression from proestrus to estrus. Progesterone concentrations revealed values above the expected which may demonstrate exacerbate pre-ovulatory luteinization. Ovaries presented high rates of growing follicles as well as ruptured, demonstrating the effectiveness of the protocol in promoting the ovulation. The follicular fluid was viscous and adhered to the oocytes. In conclusion, the employed protocol seems to be effective in the induction of the estrus in bitches.