Progesterone testing (assay) is a helpful tool used by vets to support successful breeding and healthy pregnancies in female dogs.

One of the main uses of this test is to predict ovulation - the time when your dog is most fertile. Unlike humans, dogs ovulate a couple of days after a key hormone surge, and progesterone levels start to rise around the same time. By measuring progesterone through a simple blood test, we can identify the best time for natural mating or artificial insemination, which greatly improves the chances of pregnancy.

Progesterone testing is also useful later in pregnancy to help determine when your dog is likely to go into labour. Toward the end of gestation, progesterone levels stay high until they suddenly drop - usually within 24 hours of whelping (giving birth). Knowing when this drop happens can help us prepare for a smooth delivery or schedule a planned Cesarean section if needed, especially in breeds that are known to have difficulty giving birth naturally. 

During the pregnancy itself, progesterone testing allows us to monitor the health of the pregnancy. In dogs, the pregnancy is maintained entirely by a structure called the corpus luteum, which produces progesterone. If progesterone levels drop too early, it can lead to pregnancy loss. By checking progesterone, we can spot problems early and give treatment, like hormone supplementation, if necessary to help support the pregnancy.

Overall, progesterone testing is a safe, simple, and effective way to improve breeding success, monitor pregnancy, and ensure the wellbeing of both the mother and her puppies.