Ovulation timing includes one or a combination of several techniques: vaginal cytology, vaginoscopy, serum progesterone testing and in some cases serum luteinizing hormone (LH) assay. We recommend to start with ovulation timing on day 5-7 of the heat cycle if the estrous cycle length is average (approx. three weeks), and sooner if the cycle is short (2 weeks or less). In most cases, blood collection for progesterone is recommended every 2-3 days until ovulation can be confirmed. Even if 80% of bitches will most likely ovulate on day 10 or 12, it is considered normal for a bitch to ovulate on day 4 or 24 of her heat cycle.

A common misconception is that there are fixed progesterone values around the luteinizing hormone peak as well as ovulation. Even if there is a common trend of progesterone values to be between 4 and 8 ng/ml (12 and 25 nmol/L) at ovulation, it varies dramatically between bitches and therefore, it is important to know a bitch’s baseline progesterone before making decision about her values at ovulation.

At Graham Animal Hospital, progesterone tests are done using MiniVidas laboratory equipment and test results are available within 2 hours of blood collection. The values are reported in nanograms per milliliter (ng/ml). Our laboratory follows strictest quality control procedures and our Reproductive Service staff are knowledgeable to give you advice on timing of your breeding. Please contact us as soon as your bitch comes into heat (or even prior) so we can plan your ovulation timing and breeding (or insemination). It is very important in cases when semen needs to be shipped as in fresh chilled or frozen semen breedings.