Abstract
Serial ultrasonographic examinations were performed daily on 9 Miniature Schnauzer bitches from the 15th day of gestation until parturition to determine the time the gestational structures were first detected. The gestational age was timed from the day of ovulation (day 0), which was estimated to occur when the plasma progesterone concentration was >4.0 ng/ml. The gestational length in 9 Miniature Schnauzer bitches was found to be 63.0 +/- 1.7 (range 61-65) days. The initial detection of the fetal and extra-fetal structures were as follows: gestational sac at day 18.0 +/- 0.9 (17-19); zonary placenta in the uterine wall at day 24.9 +/- 1.1 (23-26); yolk sac membrane at day 25.0 +/- 0.9 (24-26); amnionic membrane at day 27.7 +/- 1.0 (26- 29); embryo initial detection at day 22.6 +/- 0.5 (22-23); heartbeat at day 23.4 +/- 0.5 (23-24); fetal movement at day 32.5 +/- 0.8 (32-34); stomach at day 31.2 +/- 1.6 (29-33); urinary bladder at day 32.6 +/- 1.8 (31-35); skeleton at day 34.9 +/- 1.6 (34-38) and kidney at day 42.2 +/- 0.7 (41-43).