RESUMEN
Serial ultrasonographic examinations were performeddaily on 9 Miniature Schnauzer bitches from the 15th dayof gestation until parturition to determine the time thegestational structures were first detected. The gestationalage was timed from the day of ovulation (day 0), whichwas estimated to occur when the plasma progesteroneconcentration was >4.0ng/ml. The gestational length in 9Miniature Schnauzer bitches was found to be 63.0+/-1.7(range 61-65) days. The initial detection of the fetal andextra-fetal structures were as follows: gestational sac atday 18.0+/-0.9 (17-19); zonary placenta in the uterine wallat 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 day32.5+/-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 day34.9+/-1.6 (34-38) and kidney at day 42.2+/-0.7 (41-43).