Progesterone Test for Dogs and the Female Dog Heat Cycle

A dog’s heat cycle occurs approximately every 6 to 15 months, depending on the breed and genetic trends within the female dog’s family. A progesterone test for dogs can be used to determine which part of the cycle a female dog is in and whether she is receptive to mating. The canine heat cycle is divided into four phases:

1. Proestrus: Starts with swelling of the vulva and bloody vaginal discharge. This lasts an average of 9 days, with a range of 0 to 27 days.
2. Estrus: The period in which the female is receptive to mating. Ovulation occurs. Duration of estrus averages 9 days, with an average of 2 to 24 days.
3. Diestrus: The female is unreceptive to mating. Late in diestrus, mammary glands can enlarge, even if the female is not pregnant. This part of the cycle lasts for about 2 months.
4. Anestrus: The hormonally quiet period between cycles. This can last 4 to 13 months.

Using a Progesterone Test for Dogs to Determine Breeding Times

A breeder will want to know the optimal time for mating or artificial insemination to plan for breeding-related travel and to maximize litter size. This is most easily done by monitoring circulating progesterone levels using a progesterone test for dogs. During most of proestrus, progesterone hormone levels are low. Just before ovulation, progesterone levels rise precipitously, which corresponds with a surge in luteinizing hormone.

Usually, serial progesterone levels are measured every other day starting from when the bloody vaginal discharge starts, and when the progesterone is greater than 2.0 ng/mL, assume ovulation has occurred. Most progesterone tests are done through the veterinary office, using radioimmunoassay (gold standard) or chemiluminescence immunoassay.

When You Need a Progesterone Test for Dogs

Home progesterone kits measure progesterone, and while the perspective mother might be more comfortable being able to stay at home instead of traveling for a veterinary appointment, the home kits are not as accurate as the test through the veterinary office, and they will still require a blood sample.

Whichever method of progesterone testing a breeder decides upon, when measuring serial progesterone levels, it is important for accuracy to use the same lab for all the tests and pull the blood sample at the same time of day for all the tests.

Another advantage of knowing ovulation date via progesterone testing, is that the breeder will have a much better idea of whelping date (65 +/- 2 days after ovulation). This gives the breeder a time frame in which to be more vigilant in monitoring their pregnant dog and informs future puppy owners when they might be able to take their new family member home.