Determining Ovulation

The average bitch will experience the LH surge on Day 10 (where Day 1 is defined as the first day that bloody discharge is observed), will ovulate on Day 12, and will, therefore, optimally conceive on Day 14. Using receptive behavior of the female as an indicator for ovulation and therefore, a method for determining mating schedule has many limitations because these approaches are not always clear-cut. Additionally, even cytological analysis, which can be used to determine onset of estrus, is often a poor predictor for ovulation since LH surge, a key precursor to ovulation, may occur 3 to 5 days before to 5 days after the onset of estrus. Therefore, a clinical screening test that accurately predicts ovulation in the bitch and therefore serves to optimize breeding schedule, is used frequently by many breeders.

The LH serum concentration is 7 to 50 ng/ml, lasts for 24 to 40 hours before returning to basal levels, in some cases the duration of the peak is very short and can´t be detected with teh everyday measurements. Ovulation occurs 48 to 72 hours after the LH peak.  The ovulation moment can be detected, but the disadvantage is that is too short (generally 24h), for this reason the blood sample must be collected every day. Measuring LH is the less common technique and has to be additionally measured the Progesterone leves. It has been determined that the pregnant time after the ovulation peak is 64-66 days (average 65).