Assessment of Fetal Aortic, Thoracic, and Heartbeat in Healthy Donkey Pregnancies.
Authors: Magalhaes Humberto B, Canisso Igor F
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Determining pregnancy stage in donkeys with uncertain breeding histories remains challenging in clinical practice, prompting researchers to establish reliable ultrasound-based reference standards for the species. Magalhaes and Canisso performed serial transabdominal ultrasonography on 50 multiparous Dezhou donkeys at 30-day intervals from 150 days gestation through parturition, measuring fetal aortic diameter, thoracic diameter, and heart rate to correlate these parameters with gestational age in pregnancies that delivered healthy foals. Fetal aortic and thoracic measurements showed strong positive correlations with gestation length (r = 0.89 and r = 0.88 respectively), with both measurements increasing significantly from month seven to term (P < 0.001); conversely, fetal heart rate demonstrated a negative correlation (r = −0.76), remaining relatively stable from 150–270 days before declining progressively until delivery. Mean pregnancy duration was 356.6 ± 10.6 days (range 339–368 days), with normal term delivery occurring in this window. For equine practitioners managing donkey pregnancies, these findings provide objective ultrasound criteria for pregnancy staging—particularly valuable when breeding records are unavailable—and establish that declining fetal heart rate in late gestation is a normal physiological adaptation rather than a sign of compromise in healthy pregnancies.
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Practical Takeaways
- •Use fetal aortic and thoracic measurements via transabdominal ultrasonography (3.5 MHz transducer) as reliable indicators to stage donkey pregnancies and estimate delivery dates when breeding history is unknown
- •Recognize that declining fetal heart rate in late pregnancy (after 270 days) is normal in donkeys and should not be interpreted as fetal distress
- •These ultrasound parameters provide a practical, non-invasive tool for pregnancy management in donkey herds, enabling better preparation for parturition and early detection of problems
Key Findings
- •Fetal aortic diameter showed strong positive correlation with gestational age (r = 0.89) in donkeys from 150 days to term
- •Fetal thoracic diameter showed strong positive correlation with gestational age (r = 0.88), increasing significantly from seventh month to term (P < .001)
- •Fetal heartbeat remained stable from 150–270 days of gestation, then continuously decreased until parturition (P < .001), with negative correlation to gestation length (r = -0.76)
- •Mean pregnancy duration in multiparous Dezhou donkeys was 356.6 ± 10.6 days (range 339–368 days)