ULTRASONOGRAPHIC EVALUATION OF THE FETUS AND INTRAUTERINE ENVIRONMENTIN HEALTHY MARES DURING LATE-GESTATION

Mares with uncomplicated pregnancies (n = 33) underwent transabdominal sonography to evaluate fetal well-being, obtain measurements of fetal size and characterize the intrauterine environment. Data from the las t examination obtained prior to parturition were used for statistical analysis. All mares had one active fetus with good fetal tone, The max imal vertical depth of amniotic fluid (7.9 +/- 3.5 cm) was less than a llantoic (13.4 +/- 4.4 cm) and fewer echogenic particles were detected in amniotic fluid, The maximal uteroplacental thickness was 1.38 +/- 0.23 cm (retrospective) and 1.15 +/-+/- 0.24 cm (prospective), In 3 ma res small anechoic spaces were imaged between the uterus and placenta, Fetuses had a regular cardiac rhythm with a mean heart rate of 75 +/- 7 beats/minute and breathing movements. The diameter of the fetal aor ta (mean = 22.8 +/- 2.15 mm) was significantly correlated with neonata l feat weight (P < 0.0008, r = 0.72) and maternal prepartum weight (P < 0.002, r = 0.86), This information on the normal intrauterine enviro nment and fetal well-being can be used to develop a biophysical profil e specific for the equine fetus.