B-mode ultrasound and ecobiometric parameters to assess embryonic and fetal development and estimate gestational age in goats

The aim of this study was to monitor maternal-fetal ecobiometric parameters during physiological pregnancy in goats using ultrasound to predict gestational age by establishing mathematical equations. Twenty-five Saanen goats were included in the study. Assessments were performed weekly from the 21st day of pregnancy until parturition. The abdominal, thoracic, biparietal, and eye socket diameters; distance from the neck to snout; crown-rump, humerus, radius-ulna, metacarpal, femur, tibia, metatarsal, and placentome lengths; kidney height and length; and heart area were measured. Heart rate was obtained using the pulsed Doppler mode. The variables were correlated with gestational age using Spearman's test, and the adjustment of these variables to simple and multiple regression models was done to determine the mathematical formulas for calculating the gestational age. The highest obtained coefficients of determination (R2) were for humerus length (96.2), heart area (95.6), and distance from the neck to the snout (95.3). Only the placentome length and fetal heart rate presented low determination coefficients (R2 = 54.3, R2 = 45.0). The results indicated significant correlations between measures of maternal-fetal structures and gestational age, and can be used as reference values for detection of abnormalities during fetal development. •Mathematical equations to determine gestational age with predictive power above 90%.•Characterization of sonographic attributes/echogenicity of maternal-fetal structures.•Relation between gestational age and 17 biometric variables throughout goat pregnancy.•Report of echogenicity changes in the fetal lung and liver during the gestational period.•Description of ultrasound findings and their relation to physiological organogenesis.