What Is the Best Time to Progesterone Test Your Dog?
By: Responsible Group Australia Updated 20 October, 2026
If you have ever seen a bitch go into season and questioned yourself as to whether or not you bred her at the optimal time, then you are not the only one. Breeding at the correct time is one of the most frequently reported causes for a planned breeding not resulting in a litter or a litter smaller than anticipated. Progesterone testing can significantly reduce the guesswork involved in breeding decisions.
I will provide information on the timing of testing, frequency of testing, and interpretation of testing results.
Why Progesterone Testing Matters
“Day counting” is often used (mating on days 10, 12 and 14 from the start of the first discharge of blood). However, in the dog cycle this isn’t always reliable because ovulation can take place anywhere from approximately day 5 to day 20 in the cycle. Some dogs ovulate early in the cycle whilst others do so later. Some dogs may also ovulate at a different time from one season to another.
The hormone progesterone gives an indication of the bitch’s position in the cycle. Levels begin to rise before ovulation and follow a pattern which can be used to predict the breeding time with a reasonably high degree of accuracy. This is only of particular importance to those who are and:
- Using chilled or frozen semen
- Doing surgical or transcervical insemination
- Working with a stud who is travelling a long way
- Breeding a maiden, an older bitch, or one with a history of missed matings or small litters
- Wanting to estimate a whelping date more accurately
So, When Is the Best Time to Start?
Most breeders start testing at the first indication of heat (bloody discharge or vulval swelling) between days 4 and 7. Early ovulators may be first tested slightly earlier.
Factors that may influence the day to start testing include:
- Your dog’s history. If you have a regular pattern for ovulation at approximately day 10, then testing at day 5 is appropriate. For first time dogs or those with an unknown pattern, testing at days 4 or 5 is recommended.
- Signs of heat. A soft vulva, ‘flagging’ (tail up on manipulation), shift from red to pinkish-straw discharge all indicate that ovulation is in progress.
- Veterinary recommendation. Some veterinarians suggest use of vaginal cytology in addition to progesterone testing to provide a more complete picture.
If only one service is available for insemination or frozen semen is being used then it is recommended to start testing earlier rather than later since a missed progesterone rise cannot be made up.
How Often Should You Test?
- Early on (low progesterone): every 2 to 3 days is generally fine while levels are still baseline.
- Once levels start rising: test every day or every second day so you can catch the key milestones.
You’re mainly watching for three points:
Stage | Approx. progesterone | What’s happening |
Baseline | Below about 2 ng/mL (roughly 6 nmol/L) | Proestrus or early heat. Ovulation is not imminent. |
LH surge | About 1.5 to 2 ng/mL (roughly 5 to 6 nmol/L) | The brain’s signal for ovulation. Ovulation follows in about 2 days. |
Ovulation | About 5 to 8 ng/mL (roughly 16 to 25 nmol/L) | Eggs are released but not yet ready to fertilise. |
Fertile window opens | About 10 to 20 ng/mL (roughly 32 to 64 nmol/L) | Eggs have matured and fertilisation is most likely. |
Reference ranges differ between laboratories and testing methods, and many Australian labs report in nmol/L. Always use the ranges your own vet or lab provides, and where possible use the same lab for every test in a cycle.
Timing the Mating or Insemination
Dog eggs are immature at ovulation and need about 2-3 days to mature before fertilisation can take place. Therefore service should be arranged about 2 to 3 days after ovulation and not on the day of ovulation.
Your veterinarian will probably advise one of the following:
- Natural mating or AI with fresh semen: about 2 to 3 days after ovulation, often also after 48 hours
- AI with chilled semen: as above but about 2 to 3 days after ovulation
- AI with frozen semen: extremely precise timing is required as the viability of frozen sperm is restricted. Daily checks and an involved veterinarian are advised here
Which Type of Progesterone Test Should You Use?
- Laboratory (send-away) tests give precise numerical results but take longer to return.
- In-clinic quantitative tests can give same-day results and are popular with reproductive vets.
- Rapid in-clinic kits give a rough range rather than an exact number. They can be useful for tracking trends, but they’re less reliable for tight timing decisions.
Whichever you choose, try to be consistent. Switching methods mid-cycle can make results hard to compare.
Common Mistakes to Avoid
- Ovulation is too late to be detected
- Using only behaviour. Some bitches exhibit signs of standing heat either too early (before ovulation) or too late (after ovulation)
- Not testing often enough when levels are rising. Progesterone levels can rise quite rapidly
- Between different laboratories. Different testing produces different results
- Not discussing with your veterinarian. Every bitch is different and your veterinarian can adapt the timing to that particular bitch
Whelping Date: A Bonus of Testing
Progesterone levels can identify the time of ovulation which in turn can result in a much more precise estimation of whelping time. The duration of pregnancy from ovulation is approximately 63 days plus or minus a day or two. If you start from mating however there can be a week or more of uncertainty. This is useful for whelping preparations, arranging veterinary services and identifying a time frame in which missing the due date is acceptable.
Raising Dogs Responsibly Starts With Good Information
Responsible breeding involves more than just timing of reproduction. Good information, a breed community and support are all important for breeders in order to successfully carry out responsible breeding practices such as health testing, record keeping, ethical breeding, puppy agreements and contracts.
Responsible Pet Breeders Australia (RPBA) provides a responsible breeding community for all breeds in Australia. RPBA operates a vet approved code of ethics and has a system in place for new breeders to transition into full membership from probationary membership. RPBA provides breeders with agreements, records, information and handbooks and allows breeders to interact within a community of responsible breeders. Both new and experienced breeders can gain information and ask questions.
For a responsible breeder whether it is their first litter or their fifteenth, joining RPBA offers the opportunity to network with other responsible breeders, gain access to resources and convey to prospective puppy buyers that responsible breeding practices are followed.
Join Our Community
We are Australia’s largest community for all breeds. 29% of Australians have been judged by their pet’s colour, look, heritage, or breed. RPBA is an all inclusive community and we do not discriminate.
As an RPBA member, you get access to the following RPBA discounts:
Become A Registered Breeder
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