Induction of estrus in bitches with the dopamine agonist bromocriptine

The number of described reliable and practicable methods for the control of the estrous cycle of the dog are limited. The aim of this study was to test for estrus induction in bitches using bromocriptine. 23 bitches in anestrus stage were treated with 0.025 mg/kg/d bromocriptine (Bromocriptine®, Sopharma, Bulgaria) orally for three days, followed by 0.05 mg/kg/d for three days and then 0.1 mg/kg/d until day 5 after onset of proestrus. To avoid side effects, like vomiting, the daily dose was divided into two and given in the morning and in the evening. Estrus induction was successful in 22 (95.65%) bitches with a variation of 4 to 49 days until first signs of proestrus occured (vulvar bleeding) (mean 22.86±12.34 days); no estrus signs were observed in one bitch (4.35%) until day 56. Mating of the 22 bitches twice in their fertile periods determined using vaginal cytology and serum progesterone levels resulted in intact pregnancies in 19 animals (86.35%). The number of puppies ranged between 2 and 11, with an average litter size of 5.00±2.36. Our results confirm previous observations that bromocriptine offers a suitable option for induction of fertile estrus.