Estradiol benzoate priming during induction of estrus with Vitex-castus extract in dogs

This study compared two methods of estrus induction between dogs (using vitagnus and vitagnus-estradiol). A total of 10 adult cyclic female Shih tzu Terrier mix breed dogs at anestrus stage were selected and divided into two groups. The first group (VAC) received vitagnus for five weeks (90 mg daily, PO). The second group (VAC-E2) was treated with vitagnus and estradiol benzoate. Estradiol benzoate was injected at the beginning of each week (0.01 mg/kg, IM). Blood sampling for evaluation of steroid hormones and vaginal smears were taken weekly. The sings and return to the estrus with the number of puppies were recorded. In the VAC group, 60%, and in the VAC-E2 group, 80% of dogs returned to the follicular phase after five weeks. In the VAC-E2 group, signs of estrus appeared 7 to 10 days and a mating process started 4 to 6 days earlier than those in the VAC group. The average number of delivered puppies was 4. These symptoms were confirmed by the cytology of the vagina. There was no significant difference in the estradiol and progesterone levels between groups. The mean concentration of estradiol significantly changed between weeks 1 and 4, 1 and 5, and 2 and 5 (p < 0.05). The progesterone level in the VAC-E2 group on week five was higher than that in other weeks. In conclusion, the administration of estradiol benzoate before  vitagnus improved induction of estrus in dogs.