A simple log turns a series of progesterone readings into a clear picture of the trend — which is what actually determines timing, not any single number. Use this template alongside your vet’s interpretation of each result.
The most important first
- Record every reading with its date, time and lab/method — not just the number.
- The trend across readings matters more than any one value.
- Note the LH surge and predicted ovulation date as soon as your vet identifies them.
- Log the actual mating or insemination date(s) against the predicted fertile window afterward, for future reference.
The log template
For each cycle, record the following for every test:
At the top of each log, also note the Brucella canis test for the bitch and for the stud (date and result). Both dogs should have a current negative result before any mating.
- Date and time of sample.
- Progesterone result (with units — ng/mL or nmol/L, and note if the lab converts between them).
- Testing method (in-house analyzer, external lab, point-of-care device) — results can vary somewhat between methods, so consistency across a single cycle matters more than the absolute number.
- Vet’s interpretation at that point (e.g. “pre-surge,” “LH surge likely occurring,” “post-ovulation, eggs maturing”).
- Any behavioral notes for that day (standing for the male, discharge color/consistency, vulval softening) — useful context, though not a substitute for the hormone result.
Labs in the US usually report progesterone in ng/mL, while many labs in Europe, Canada and Australia use nmol/L. One ng/mL is about 3.18 nmol/L, so a result of 2 ng/mL is roughly 6 nmol/L. Write the unit next to every number, and never compare readings in different units or from different machines without checking with your vet.
Once a trend is established, add:
- Estimated LH surge date (identified retrospectively once progesterone shows a clear rise).
- Estimated ovulation date (about two days, 48 to 72 hours, after the LH surge).
- Recommended mating/insemination window, as advised by your vet, based on the semen type being used.
- Actual mating or insemination date(s), logged against the predicted window.
- Estimated due date — usually 64 to 66 days after the LH surge your vet identified.
Why keep this record
Beyond guiding the current cycle, a completed log is valuable evidence if a mating doesn’t result in a pregnancy and infertility investigation becomes necessary — it lets a vet see whether timing was actually correct, narrowing down whether the cause lies elsewhere. It’s also useful for predicting future cycles in the same bitch, since cycle characteristics often (though not always) repeat.
Treat that as a guide to when to start testing, not a substitute for testing: one cycle can differ quite a lot from the last, so each cycle needs to be timed on its own. Your log also shows when to pick up the phone — if progesterone rises and then stays flat for more than about three days, if it has not started to rise well into the season, or if the season itself seems to last more than about 40 days, ask your vet about further checks such as an ultrasound scan.
In practice
After a mating that didn’t result in a pregnancy, a breeder without detailed records can only guess at whether timing was the issue. A breeder with a full progesterone log can show their vet exactly when the LH surge and predicted ovulation occurred, and when mating happened relative to that — turning a vague “it didn’t work” into a specific, investigable question.
(Illustrative, composite scenario.)
(Illustrative, composite scenario.)
When to call your vet
- Progesterone rises and then stays flat for more than about three days.
- Progesterone has not started to rise well into the season, or the season lasts more than about 40 days.
- Results in your log come from different units, labs or machines and do not line up — check before choosing a mating day.
- Either dog lacks a current negative Brucella canis result in the log.
- She reaches about day 66 from the LH surge (about 70 days after the first mating) without labor starting.
- If in doubt, call — your vet would rather hear from you early.
Work on it
A few minutes here will teach you more than re-reading the article.
Ask yourself
- Do I have a consistent place to log every progesterone result, not just remember them?
- Am I recording enough detail (method, units, vet interpretation) to make the log useful later?
Find out & check
- Find out whether your vet or testing lab provides a standard results sheet you can build this log around.
Do one thing
- Set up your progesterone log — even a simple spreadsheet or notebook page — before your next test is due.
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Sources & further reading
- Merck Veterinary Manual — Breeding Management of Bitches. merckvetmanual.com
- UC Davis School of Veterinary Medicine — Breeding Management of the Bitch. healthtopics.vetmed.ucdavis.edu
- University of Guelph Animal Health Laboratory — Serum progesterone in various species. uoguelph.ca
- Zuercher J et al., Frontiers in Veterinary Science (2021) — Comparison of a Point-of-Care Analyzer With a Chemiluminescent Immunoassay for Serum Progesterone Measurement in Breeding Management of the Bitch. frontiersin.org
- American Kennel Club — 20 Facts You Should Know About Timing of Ovulation in the Bitch. akc.org
- Concannon PW, Animal Reproduction Science (2011) — Reproductive cycles of the domestic bitch. doi.org
- UC Davis School of Veterinary Medicine — Ovulation Timing in the Dog. healthtopics.vetmed.ucdavis.edu
Where evidence is limited, recommendations rest on established practice and expert judgment, and may be updated as knowledge develops.
Next steps
- Related: Timing the mating: finding the fertile window · Infertility in the bitch and dog.
- Return to the area hub: Reproduction and fertility.