ULTRASONOGRAPHIC EVALUATION OF THE FETUS AND INTRAUTERINE ENVIRONMENT IN HEALTHY MARES DURING LATE GESTATION

Authors

  • Virginia B. Reef DVM,

    Corresponding author
    1. Department of Clinical Studies (Section of Medicine), New Bolton Center, University of Pennsylvania, 382 W Street Rd, kennet Square, Pa. 19348.
      Address all correspondence and reprint requests to Dr. Virginia B. Reef, Department of Clinical Studies (Section of Medicine), New Bolton Center, University of Pennsylvania, 382 W Street Rd, Kennett Square, PA. 19348.
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  • Wendy E. Vaala VMD,

    1. Department of Clinical Studies (Section of Medicine), New Bolton Center, University of Pennsylvania, 382 W Street Rd, kennet Square, Pa. 19348.
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  • Leila T. Worth VMD, PhD,

    1. Department of Clinical Studies (Section of Medicine), New Bolton Center, University of Pennsylvania, 382 W Street Rd, kennet Square, Pa. 19348.
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  • Pamela A. Spencer ScM,

    1. Department of Clinical Studies (Section of Medicine), New Bolton Center, University of Pennsylvania, 382 W Street Rd, kennet Square, Pa. 19348.
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  • Barbara Hammett

    1. Department of Clinical Studies (Section of Medicine), New Bolton Center, University of Pennsylvania, 382 W Street Rd, kennet Square, Pa. 19348.
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Address all correspondence and reprint requests to Dr. Virginia B. Reef, Department of Clinical Studies (Section of Medicine), New Bolton Center, University of Pennsylvania, 382 W Street Rd, Kennett Square, PA. 19348.

Abstract

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 last examination obtained prior to parturition were used for statistical analysis. All mares had one active fetus with good fetal tone. The maximal vertical depth of amniotic fluid (7.9 ± 3.5 cm) was less than allantoic (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 (propspective). In 3 mares 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 aorta (mean = 22.8 ± 2.15 mm) was significantly correlated with neonatal foal weight (P<0.0008, r = 0.72) and maternal prepartum weight (P<0.002, r = 0.86). This information of the normal intrauterine environment and fetal well-being can be used to develop a biophysical profile specific for the equine fetus.

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