Progesterone Test for Dogs: When to Test and What the Results Mean

Trying to identify the right time to mate a female dog can be a tricky process. Some dogs show clear physical and behavioural changes during their season, while others give very few reliable clues. Counting a set number of days from the first sign of bleeding may seem straightforward, but every dog’s cycle is different.

A progesterone test for dogs can provide a clearer picture of where a female dog is in her reproductive cycle. By monitoring how her progesterone level rises, testing can help identify ovulation opportunities and guide the timing of natural mating or artificial insemination.

It is important to remember that a single result rarely tells the whole story. Repeat tests, the type of semen being used, and the testing method can all influence how the result should be interpreted. In this article, we will cover some key information about progesterone testing in dogs, including what progesterone tests are and when they should be used for maximum efficiency. 

What is a progesterone test for dogs?

A progesterone test is a blood test that measures the level of the hormone progesterone in a female dog’s bloodstream. Progesterone starts to rise around the time of the luteinising hormone surge and continues to increase during ovulation and the fertile period. The test can help breeders understand whether a dog is:

• Still early in her season
• Approaching ovulation
• Likely to be ovulating
• Moving into the period when her eggs may be mature

However, progesterone testing does not guarantee pregnancy. The health and fertility of both dogs, semen quality, breeding method and any underlying reproductive concerns can still affect the outcome. Progesterone testing is used to help reduce the risk of mating too early or too late.

When should progesterone testing begin?

There is no single starting day that will be right for every dog. Testing often begins several days after the first signs of the season, such as vulval swelling or a bloody discharge.

The first blood sample provides a starting point. If the progesterone level remains low, another test may be recommended after 24 or 48 hours. As the level begins to rise, closer monitoring can help identify the likely ovulation window.

Contacting a fertility professional when the season starts can make it easier to plan the first appointment. It helps to record:

• The first day you noticed bleeding or swelling
• Changes in the colour or amount of discharge
• Changes in behaviour around male dogs
• The length and timing of previous seasons
• Any previous progesterone test results
• Whether natural mating, fresh, chilled or frozen semen will be used

Our dog fertility services in East Sussex include ovulation testing and practical support for owners planning a mating, maximising your chances of a successful insemination attempt.

What happens during a dog’s progesterone test?

During the appointment, a small blood sample is taken and analysed to measure the hormone level. Results may be shown in nanograms per millilitre, written as ng/mL, or nanomoles per litre, written as nmol/L.

Always check which unit has been used before comparing the result with an online chart. Testing machines and laboratory methods can also produce slightly different readings, and a number from one machine should not automatically be treated as identical to the same number from another.

Depending on the result, you may be advised to arrange another test. Repeat testing is not a sign that the first appointment was unsuccessful. Following the pattern of change is often more helpful than relying on one isolated number.

What should a dog progesterone level be to breed?

There is no single progesterone level that means every dog should be bred immediately.

The result needs to be considered alongside the direction in which the hormone is moving, the measurement method and the planned breeding method. Fresh semen can survive for longer inside the female reproductive tract, while chilled or frozen semen generally requires more precise timing.

The figures below are broad examples rather than instructions for breeding without professional interpretation.

General stage	What the result may suggest	Possible next step
Low or baseline level	The dog may still be early in her cycle	Repeat the test as advised
Progesterone beginning to rise	The luteinising hormone surge or ovulation may be approaching	Monitor more closely
Around the ovulation range	Ovulation may be taking place	Plan according to semen type
Clear post-ovulation rise	The eggs may be approaching maturity	Confirm the recommended mating time

What progesterone level may indicate ovulation?

Some veterinary guidance places ovulation at approximately 5 to 10 ng/mL, although broader ranges are sometimes given because analysers and individual dogs can vary.

The eggs are not immediately ready for fertilisation when they are released. They normally need another two to three days to mature. A result suggesting that ovulation has taken place does not always mean mating should happen that same day.

This is why the result should be interpreted by a professional dog breeder, rather than read from a chart alone.

Does the type of mating affect the best time to breed?

The suitable timing can change depending on whether natural mating, fresh semen, chilled semen or frozen semen is being used.

Fresh semen usually survives for longer within the female reproductive tract, which can provide a wider opportunity for fertilisation. Chilled semen has a shorter useful lifespan, while frozen semen generally requires the narrowest timing window.

If you already have a breeding method you plan to use, let us know ahead of time. This allows us to interpret the result with that information in mind.

Owners who are still looking for a suitable male can view our available stud dog services and discuss the health, temperament and breeding requirements of the dogs involved.

How many progesterone tests will a dog need?

Many dogs require two or three progesterone tests, although some may need more. The number of tests can depend on:

• How early testing begins
• How quickly the progesterone level rises
• Whether the start of the season is clear
• Whether the dog has irregular or silent seasons
• The breeding method that has been planned

For example, a low reading early in the season may simply show that the dog has not yet reached the relevant stage. A repeat sample can reveal whether the level is remaining steady or starting to rise. Because of this, testing should be viewed as a process, rather than a one-off pass-or-fail result.

Can behaviour tell you when a dog is ready to mate?

Behaviour can provide useful clues, but it cannot confirm ovulation on its own.

A female dog may move her tail aside, stand for a male or become more interested in other dogs. A stud dog may also show increased interest. However, these signs do not always match the most fertile point in the cycle.

The same applies to discharge. Changes in colour or amount may suggest that the season is progressing, but they do not provide an exact breeding date.

Vaginal cytology may sometimes be used alongside progesterone testing to provide more information about the stage of the cycle. Your vet or fertility professional can explain whether additional testing may be helpful.

Can progesterone testing help predict the due date?

Identifying ovulation can help estimate a whelping date more accurately than counting from the day of mating alone.

Mating may happen before or after ovulation, and fresh sperm can remain viable for several days. Dogs commonly give birth around 62 to 64 days after ovulation, although pregnancies and individual circumstances vary.

Knowing the likely ovulation date can help breeders prepare for whelping and recognise when veterinary advice may be needed.

Responsible breeding also involves suitable health testing, careful pairing and planning for the puppies’ long-term welfare. You can read more about our approach as responsible and experienced dog breeders</a>.

What should you do when your dog’s season begins?

Start by recording the first day you notice bleeding, swelling or other changes. Avoid relying on a fixed day of the season, particularly if your dog has previously ovulated earlier or later than expected.

If you are planning a litter, contact Perfect Pooches as soon as the season begins. Tell us:

• When you first noticed the signs
• Whether the cycle appears normal for your dog
• Which stud dog or semen type you plan to use
• Whether she has had previous progesterone testing
• Any concerns about her reproductive health

We can discuss when the first test may be appropriate and explain the likely next step once the result is available.

Make breeding decisions with clearer information

A progesterone test for dogs can help remove some of the uncertainty surrounding ovulation and mating dates. The most useful approach is usually to start at a suitable point in the season, check the units used and follow the pattern across repeat results.

Every dog is different, so numbers should always be considered alongside her cycle, health and planned breeding method.

To discuss progesterone testing or arrange an appointment, contact the Perfect Pooches team when your dog’s season begins. We can talk through the information you have, help you plan the timing and explain what happens next.