CASE 6. Ovulation timing
Ovulation can be timed prospectively, with measurement of progesterone in serum, and retrospectively, by identification of the first day of diestrus (D1). For prospective determination of ovulation date, remember that progesterone in the range of 2 to 2.9 ng/ml is indicative of the day of the LH surge and that progesterone on ovulation day ranges from 4 to 10 ng/ml. For retrospective determination, remember that ovulation occurs 6 days prior to D1.
Question: Using the following vaginal cytology specimens and serum progesterone concentrations, determine ovulation date in this bitch.
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December 15 Progesterone = 0.5 ng/ml |
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December 18 Progesterone = 0.6 ng/ml |
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December 20 Progesterone = 0.5 ng/ml |
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December 22 Progesterone = 2.1 ng/ml |
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December 24 Progesterone = 9.9 ng/ml |
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December 27 Progesterone = 15.6 ng/ml |
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December 29 Progesterone = 29.0 ng/ml |
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December 30 Progesterone = 32.3 ng/ml |
Answer:
Progesterone indicates ovulation on December 24. That is verified by vaginal cytology; onset of diestrus is December 30 (December 30 minus 6 days = December 24). Optimal breeding day by natural service or with fresh or chilled semen is December 26. Optimal breeding day with frozen semen is December 27 or 28.