Experienced dog breeders are aware of the value of progesterone testing.

It is recognized that in the dog up to 75% of failures to conceive can be attributed to incorrect timing of breeding.

The reason it is so difficult to time ovulation in the absence of hormone testing is that the stages of the canine estrous cycle vary considerably in length. Pro-estrus is defined as the period from onset of vulvar bleeding to the first acceptance of copulation; its duration averages 9 days, but it can range from 1–27 days in extreme cases.

It is also a common misconception among breeders that the duration of the different stages within a heat cycle and the point at which a bitch will allow copulation replicates itself in each repeating heat cycle of each individual bitch. For example, because a bitch was previously successfully bred on day 10 (starting from first signs of heat), the breeder will keep on mating that specific bitch on day 10. While this might work in some cases, it most certainly won’t work in all cases. It is not always true that the stud will know exactly when the bitch is at her peak and at her optimum time for fertilization. More precise timing of the breeding events is required when there is limited access to the stud, when artificial reproductive techniques are going to be used, or when the quality of the semen is questionable.

Optimal timing helps breeders in the following ways:

• Maximizes pregnancy rates and litter size (Semen and stud fees are expensive.)

• Allows the breeder to plan travel for matings

• Allows optimization of time for assisted breeding techniques (artificial insemination [AI] using fresh, chilled, or frozen sperm)

• Allows optimization of time for breeding when access to the stud is limited to one or two matings

• Prevents unnecessary use of male

• Helps with the planning of matings when the same male is used on two bitches simultaneously

• Allows optimization of time for breeding in bitches that have a history of unreceptiveness or show silent heats

• Ovulation timing for fair estimates of expected whelping dates

Below is data collated from dogs scanned here

PLEASE NOTE - It is very important that you use a vet to draw blood from your bitch for the purpose of progesterone testing. There are numerous fertility clinics around the Country, they offer a range of breeding services, they look professional and breeders believe it is all legal and they are suitably trained. Unfortunately they are not qualified to draw blood from your bitch for the purpose of progesterone testing, even if they get you to sign a disclaimer and tell you they are trained. A registered veterinary nurse is not insured to draw blood from any animal without a vet on the premises neither is a trained human Phlebotomist. So whatever they tell you, and whatever disclaimer they get you to sign, they are not allowed to put a needle into your dog and draw blood unless they have MRCVS after their name.

To reduce stress on your dog, blood should be drawn quickly and efficiently from the cephalic vein. I am also finding that the results given by the machines from these clinics are hit and miss with a very low success rate of dogs becoming pregnant. Idexx use sophisicated testing machines and are currently charging £46 for a progesterone test (April 2021).

Not a week goes by that I don't have clients in who have used one of these clinics who they believe are trained and qualified to draw blood and their dog has been, in their words 'stabbed numerous times'. It is illegal, and if anything should go wrong they will not be trained in how to stop the bleeding.

You can read more about it, or watch the BBC documentary - see HERE

Apart from the illegal aspect, breeders are spending considerable amounts of money for progesterone testing, stud fees and AI, and with unreliable testing, the pregnancy success rate based on my experience is very low.

The only easily tested, reliable method of predicting ovulation in the bitch is a progesterone test. Ovulation occurs two days after the LH surge when progesterone levels are between 15 and 20 nmol/l. Most vet practices will take a blood sample, send it to a lab and have the result the next day. A premate test (in house blood test) is a useful indicator of progesterone levels, but it only gives a guide to progesterone levels.

After ovulation it takes approximately 48 hours for eggs to mature before they can be fertilised, and it takes around 12 hours after ejaculation for fresh sperm cells to be able to fertilise an egg. Luckily canine sperm cells can live for up to five days once deposited inside the reproductive tract of the bitch, so although the best time to mate is two days after ovulation, matings just before ovulation can still produce puppies. If possible, two matings (24 – 48 hours apart) are recommended.

Progesterone testing is especially important if your bitch has failed to produce a litter previously and is vital when using chilled or frozen semen.

If you prefer Vaginal Cytology as opposed to a blood test, this is a skill that you can't learn overnight on a days training course. A friend of mine in Kent has been doing cytology testing for years, and if you would like a test kit which you can return to her by post, please give her a ring. Val Brown ch. M. I. A. C. E. DBC. - Mertrisa Collies Telephone: 01444 453232



Blood Sampling Order 1983

Chilled semen will only survive for 24 hours after warming, and frozen semen even less time at approximately 12 hours. So timing is vital in these cases, and to improve chances of success the sperm are usually helped on their way by placing them directly into the uterus rather than the vagina.

There are a few reputable ultrasound scanners who are able to confirm ovulation using swabs, a method called cytology, but there are also a lot of so called 'do it all 'fertility clinics offering all aspects of fertility, including cytology, and due to the lack of training they are giving false results. Do your homework and get recommendations from breeders/friends.

It is worth noting that Progesterone levels continue to increase for two to three weeks after ovulation, reaching 10 to 80 ng/ml. This level remains for about 60 days regardless of whether the dog is bred or not. Progesterone levels drop to 2 ng/ml about 48 hours before whelping, dropping to 1 ng/ml about 24 hours before whelping.

If you have any queries about progesterone testing, I am happy to advise, I also have some Idexx blood test kits here if you need one.


Useful for vets before performing a C section to check hormone levels have dropped and puppies are ready to be born.





If you are a breeder please be aware that from 6th June 2022 onwards, all progesterone tests (also known as premate tests) must be submitted under a veterinary practice account. We will no longer be accepting direct submissions at our laboratories from members of the public. This decision has been made due to the scrutiny on dog breeding and the increase in non-veterinary fertility clinics setting up, which has raised questions on the legality of blood sampling of dogs. Taking a blood sample from a dog, or any animal, is considered to be an act of veterinary surgery and should only be undertaken by a veterinary surgeon or someone under their supervision. There will be no change to the quality of service and support you receive from IDEXX, only that submissions must now come to us directly from a veterinary practice.


Cats are slightly different to dogs and the queen can be bred at any time when in heat. Cats are induced ovulators, which means that the act of breeding stimulates the release of eggs from the ovaries. Most females require three to four matings within a 24-hour period for ovulation to occur. It only takes a minute or two for cats to mate, and cats may mate multiple times in a short period of time. Queens may mate with several different tomcats during this time, so it is possible that a litter of kittens may have several different fathers. Once ovulation has occurred, the queen will go out of heat within a day or two.