Repeatability of events during spontaneous and gonadotrophin-induced oestrus in bitches.

Oestrus induction using equine chorionic gonadotrophin and human chorionic gonadotrophin was successful in five out of six bitches, although the first day of increased plasma progestagen concentration differed considerably between bitches. Induced oestrous periods differed from spontaneous cycles in the timing of vaginal epithelial cell cornification; plasma oestrogen concentrations were generally greater and progestogen concentrations were less in induced cycles. These results suggest that this schedule of oestrus induction would not be suitable for allowing mating on a predetermined day.