The dog pregnancy rates are approximately 63 days from the day of ovulation. Mothers around that time can initiate contractions. To find a specific date for conception, ovulation can be evaluated by testing the progesterone levels.
Considering the dog is in heat. The progesterone will increase up to 5ng to some extent, considering that the thermal cycle is progressing. It will take two weeks for the eggs to develop and be ready for fertilization once the eggs have been released. In cases where contractions begin 56 days after birth, the fetus does not grow with the puppies and cannot be fertilized.
Ultrasound
If you want to know if your dog is pregnant, there are several ways on how to find out. You can perform ultrasound tests after 21 days from ovulation to see if there are fetuses in the uterus. It is a safe procedure for your dogs and does not require sedation of the mother. The fetuses are growing, and the count is accurate, and it becomes more challenging to get a count as the pregnancy progresses. On the ultrasound, the fetuses may appear as circles.
Palpitation of the Abdomen
This should be done with a breeder or veterinarian, and handling fetuses can damage or cause a miscarriage. The fetuses are scattered on each of these two uterine horns. The fetuses become dependent on how large the breed is. Sampling may be performed after breeding; it may not give an accurate count, but it may indicate that the female is a carrier of puppies. After the 35th day, palpitations cannot be detected.
Blood Test
Blood tests that check the Relaxin level of the female could be done after 28 days and are accurate but will not give the puppy a number. The kits are available online. You can wait until you see signs of pregnancy in your dog. An x-ray during the final week of her pregnancy will determine the number of puppies.