Progesterone testing is a blood test that is used to determine optimal time for breeding. A peak in the progesterone levels in the blood correspond with an increase in the leuteinizing hormone. When these levels rise it indicates that ovulation will take place in 48 hours. By detecting the spike in progesterone levels in the blood we can determine the optimal breeding time.
The first progesterone test should be taken 7-9 days after the bitch shows signs of being in heat. This can include the first sign of blood or swelling. The test is then repeated every 48 hours until there is a spike in the progesterone level. Some require 2-4 tests, while others more, depending on the bitch.
When the progesterone levels spike breeders should skip one day and breed the next two consecutive days. Breeding twice can increase the chance of fertilization as well as increase litter sizes.