Abstract
Eleven anestrous bitches were injected intramuscularly (i.m.) with pregnant mare serum gonadotropin (PMS) (44IU/kg/day) for 9 consecutive days, followed by human chorionic gonadotropin (hCG) (500IU/head) on the 10th day of treatment to induce estrus. The same regimen of treatment was applied to 4 bitches in metestrus following a systematic i.m. injection of prostaglandin F2α-Tham salt (30μg/head) at an interval of 12 hr for 48 hr. Behavioural estrus was exhibited in 7 of the 11 anestrous bitches within 15±3 days after the initial treatment and in all of the 4 metestrous bitches within 16±8 days after the first injection. All the estrus-induced bitches were mated with fertile male dogs and 2 animals (1 from anestrous and 1 from metestrous bitches) conceived. Two of the 4 anestrous bitches not exhibiting behavioural estrus after treatment were inseminated artificially. One of them became pregnant. Blood progesterone profiles showed that most of non-pregnant bitches had an insufficient luteal phase. These results indicate that estrus was successfully induced with PMS and hCG in the bitch during metestrus (requiring pretreatment with prostaglandin) and anestrus, but the pregnancy rate at induced estrus is discouraged. Failure to establish pregnancy after mating at induced estrus was most likely due to insufficient luteal function.
