The earliest pregnancy can be detected is via ultrasound as early as day 20-22 after breeding. Pending body condition of the mother and number of puppies uterine enlargement can be palpated sometime between days 25-50 of pregnancy. Fetal skeletons calcify at day 45 and can be seen on x-ray. This is the best way to estimate the number of puppies. Gestation (pregnancy) in dogs lasts 63-66 days.
