Relationship of reproductive behavior, serum luteinizing hormone and time of ovulation in the bitch

This study was performed to define the relationship betweed luteinizing hormone (LH), repro-ductive behavior and time of ovulation in the domestic bitch. Laparoscopy was effective for dis-tinguishing ovarian follicular development and the morphological alterations indicative of ovula-tion and corpus tuteum (CL) formation. The actual moment of follicular rupture was observed in 2 animals. An LH surge was detected in all animals and mean LH values did not differ between bitches subjected to laparoscopy at 48 h intervals and those bitches which did not undergo laparoscopy during the experiment. During the proestrous-estrous period, baseline LH concentrations before and after the LH surge averaged 1.7 ± 0.1 ng/ml (S.E.). The major preovulatory LH surge ranged from 11.0-90.3 ng/ml with an average of 45.1 ± 4.4 ng/ml (S.E.) The duration of the LH surge was prolonged and occurred over a 3.5-4 day period. In 52 % of the cycles examined, an episodic burst of LH (mean 6.1 ± 0.9 ng/ml) was detected 3-9.5 days prior to peak preovulatory concen-trations of LH. This early release of gonadotropin may be associated with preovulatory luteiniza-tion and early progesterone secretion by the follicle. Evidence of ovulation was found in 9 3.5