Dog Progesterone & Ovulation Timing Calculator

Why Progesterone Drives Canine Reproductive Timing

Unlike most mammals, bitches ovulate during a single window that progesterone reveals. Behavioural signs (proestrus bleeding, oestrus willingness to stand) are useful but far less precise than serum progesterone — a single in-house or reference-lab test reads where in the cycle the bitch is, with implications for breeding, artificial insemination, and whelping prediction.

The standard canine progesterone thresholds (Concannon 1989; Kutzler 2003):

Progesterone (ng/mL)	Equivalent (nmol/L)	Cycle stage
<1	<3	Anoestrus or very early proestrus
1-2	3-6	Early proestrus, pre-LH surge
~2	~6	LH surge (the trigger event)
4-6	13-19	OVULATION
5-10	16-32	Ovulation period — oocytes maturing
~20	~63	Peak fertile post-ovulation
50+	159+	Dioestrus / pregnancy maintenance

Unit conversion: 1 ng/mL = 3.18 nmol/L. US labs typically report ng/mL; UK and SI labs typically report nmol/L.

The Unusual Canine Reproductive Biology

Three features distinguish canine fertility timing:

1. Bitches ovulate primary oocytes — the oocytes need 2 days to mature after ovulation before they can be fertilised.
2. Sperm survives 3-7 days in the reproductive tract.
3. Both eggs and sperm have long fertile windows — matings from 2 days before to 5 days after ovulation can result in pregnancy.

This means the optimal mating window is 2-5 days after ovulation (i.e. when progesterone is in the 10-20 ng/mL range), but earlier and later matings can still succeed. Progesterone testing lets you place matings within that optimal window precisely.

The Practical Breeding Protocol

The standard protocol used by reproduction vets:

1. Start checking progesterone 6-9 days into proestrus (when behavioural signs begin)
2. Repeat every 24-48 hours
3. When progesterone reaches ~2 ng/mL, recheck in 24 hours — LH surge is around now
4. When progesterone reaches 4-6 ng/mL, ovulation is happening
5. Optimal natural matings: 2-4 days after ovulation
6. Optimal AI varies by semen type:

• Fresh chilled semen: 2-4 days after ovulation
• Frozen semen: 2-3 days after ovulation (less sperm survival, narrower window)

1. Ultrasound for pregnancy confirmation at day 25-30 from ovulation
2. Radiograph for puppy count at day 55
3. Temperature monitoring twice daily from day 58

Measurement Methods

In-House Chemistry Analysers

• Tosoh AIA, IDEXX SNAP Pro progesterone, Eickemeyer ProCyte — used in many GP and repro clinics
• Same-day results — essential for ovulation timing
• Generally accurate enough for timing decisions but inter-machine variation exists

Reference Laboratory Chemiluminescence

• Most accurate but adds 24 hours turnaround
• Useful for confirming in-house results in borderline cases
• Standard for definitive cycle staging

What to Trust

Use one consistent laboratory or one in-house machine for serial measurements during a cycle. Inter-method variation can confuse the picture. The trend across multiple readings is more informative than any single result.

Whelping Date Prediction From Progesterone

Once ovulation is identified (progesterone 5-6 ng/mL marker):

• Whelping due 63 ± 1 days from ovulation
• 65 ± 1 days from LH surge (LH surge ~2 days before ovulation)

This is far more precise than dating from mating, where the wide fertile window produces a 58-68 day range from any individual mating.

The pre-whelping progesterone drop below 5 ng/mL approximately 24-36 hours before parturition is the most reliable hormonal predictor of imminent labour, combined with the rectal temperature drop below 37.2 °C / 99 °F.

For the full pregnancy milestone calendar (ultrasound at day 25-30, radiograph at day 55, temperature monitoring from day 58), see the PuppaDogs Pregnancy / Whelping Due-Date Calculator.

Brachycephalic Breeding

For severely brachycephalic breeds (French Bulldogs, English Bulldogs, Pugs, Pekingese), elective C-section is the standard. The C-section is timed precisely by:

• Progesterone-based ovulation timing (sets day 0)
• Day 62-63 from ovulation for elective C-section (vs natural whelping around day 63 in non-brachy breeds)
• Pre-operative ultrasound to confirm puppy viability
• Vet hospital booking well in advance of the predicted date

Without progesterone-based timing, elective C-section dates are guesses with substantial risk of premature delivery (puppies not fully developed) or post-mature delivery (dam in labour, puppies in distress).

Common Errors

Mistaking the LH surge for ovulation

LH surge happens when progesterone reaches ~2 ng/mL. Ovulation is 2 days later when progesterone reaches 4-6 ng/mL. Mating at LH surge is too early by 2-4 days — sperm will have died before oocytes mature.

Single-point testing

A single progesterone reading often doesn’t capture the cycle dynamics. Repeat testing every 24-48 hours during the relevant window catches the rise more reliably.

Inter-lab confusion

The same blood sample tested at different labs (or on different machines) can read differently. Use one source for serial measurements during a cycle.

Confusing units

ng/mL × 3.18 = nmol/L. A progesterone of “5” is very different depending on units — 5 ng/mL is ovulation; 5 nmol/L is barely above anoestrus. Always check the unit on the lab report.

Frozen semen with natural-mating timing

Frozen semen has shorter sperm survival than fresh. Optimal AI window for frozen is 2-3 days after ovulation, narrower than for natural mating. Time precisely.

Honest Caveats

• Progesterone testing has inherent variability — values are approximations, not absolutes. The trend matters more than any single point.
• Breed differences exist but are smaller than the inter-individual variation within breeds.
• Pyometra and progesterone-secreting tumours can produce elevated progesterone outside the normal cycle context — clinical correlation matters.
• This calculator gives cycle-stage interpretation — not a complete breeding plan. Reproduction vets bring substantial added value for difficult cases, AI procedures, and brachycephalic timing.
• The thresholds presented are typical canine values; individual bitches can vary by 20-30%.

Conclusion

Canine reproduction timing is built around serum progesterone measurement — the single most useful test for ovulation timing, mating planning, AI scheduling, and whelping prediction. The standard thresholds (Concannon / Kutzler) map progesterone levels to cycle stage with practical implications at each tier. Serial measurement across the proestrus / oestrus transition is the gold standard; a single measurement gives a snapshot but cannot replace the trend. Used together with the PuppaDogs Pregnancy / Whelping Due-Date Calculator, this tool covers the reproductive cycle from heat onset through whelping.

Frequently Asked Questions

What is a normal progesterone level for a dog?

Progesterone is INTERPRETED BY CYCLE STAGE rather than against a single ‘normal’ value. The standard canine thresholds: <1 ng/mL anoestrus; 1-2 ng/mL early proestrus pre-LH; ~2 ng/mL LH surge; 4-6 ng/mL ovulation; 5-10 ng/mL ovulation period; ~20 ng/mL peak fertile post-ovulation; >50 ng/mL dioestrus / pregnancy maintenance. Unit conversion: 1 ng/mL = 3.18 nmol/L.

When should I breed my dog based on progesterone?

Optimal natural matings are 2-4 days after ovulation – when progesterone is in the 10-20 ng/mL range. Frozen semen AI is 2-3 days after ovulation (narrower window due to shorter sperm survival). Fresh chilled AI is 2-4 days after ovulation. Ovulation itself is identified when progesterone reaches 4-6 ng/mL – the 2-day delay between ovulation and optimal mating reflects the fact that canine oocytes need 2 days to mature after ovulation before they can be fertilised.

How accurate is progesterone testing for ovulation timing?

Very accurate when used properly – canine reproduction vets routinely time breedings to within 24-48 hours using serial progesterone measurements. Key principles: use ONE laboratory or one in-house machine for serial readings (inter-lab variation can confuse the picture); test every 24-48 hours during the relevant window; trust the TREND across multiple readings more than any single result. Single-point testing often misses the precise ovulation moment.

What is the LH surge and how does it relate to progesterone?

The LH (luteinising hormone) surge is the trigger that causes ovulation 2 days later. In dogs, LH surge corresponds to progesterone reaching about 2 ng/mL (6.4 nmol/L) – so progesterone is used as a marker for the LH surge in routine practice. Direct LH measurement is also available but less commonly used than progesterone for ovulation timing because progesterone gives the same information plus extra detail about the days post-ovulation.

How do I predict my dog’s whelping date from progesterone?

Canine gestation is 63 +/- 1 day from ovulation, or 65 +/- 1 from LH surge. Once you have identified ovulation (progesterone reaching 5-6 ng/mL), whelping is due approximately 63 days later. Pre-whelping signs: progesterone drops below 5 ng/mL approximately 24-36 hours before parturition; rectal temperature drops below 37.2 C (99 F) about 24 hours before labour. Combined these are the most reliable predictors of imminent whelping.

Why do brachycephalic dogs need precise ovulation timing?

French Bulldogs, English Bulldogs, Pugs, Pekingese and similar severely flat-faced breeds usually require ELECTIVE CAESAREAN SECTION because puppies’ large heads do not pass through the dam’s narrow pelvis. The C-section is timed precisely – typically day 62-63 from ovulation (when progesterone first reached 5-6 ng/mL). Without progesterone-based timing, C-section dates are guesses with substantial risk of premature delivery (puppies not fully developed) or post-mature delivery (dam in labour with puppies in distress).

Related PuppaDogs Calculators

Continue building your dog’s personalised care plan with these related PuppaDogs calculators:

• Dog Pregnancy / Whelping Due-Date Calculator
• Puppy Weight Predictor (Adult Weight Calculator)
• Heatstroke Risk Calculator for Dogs
• Bloat (GDV) Risk Calculator for Dogs
• Dog Life Expectancy Calculator (Breed, Body Condition, Lifestyle)
• Spay/Neuter Timing Calculator for Dogs (Breed-Specific)

References & Further Reading

The dosing ranges and safety information on this page are drawn from the following veterinary references. Always defer to your own veterinarian and the manufacturer’s label for your specific product.

1. Concannon PW. Reproductive cycles of the domestic bitch. Animal Reproduction Science, 2011 – the canine reproductive cycle review.
2. Kutzler MA. Canine ovulation timing using progesterone measurement. Veterinary Clinics of North America: Small Animal Practice, 2003.
3. Root Kustritz MV. The dog breeder’s guide to successful breeding and health management, 2nd ed.
4. Goodman M, Concannon PW. Use of progesterone radioimmunoassay in canine reproductive management. Theriogenology archives.
5. Linde-Forsberg C. Artificial insemination with fresh, chilled extended, and frozen-thawed semen in the dog. Theriogenology, 1995.
6. WSAVA Reproduction Control Committee resources.
7. PuppaDogs. Pregnancy / Whelping Due-Date Calculator. puppadogs.com.