Fetometry in Arabian horses.
Authors: Ali Ahmed, Derar Derar R, Alaeyeari Ahmad A, Alharbi Yousef M
Journal: Frontiers in veterinary science
Summary
# Fetometry in Arabian Horses: Ultrasonographic Standards for Fetal Development and Sex Determination Establishing reliable ultrasonographic parameters for in-utero fetal development is essential for optimising reproductive management and early intervention strategies in Arabian horse breeding programmes. Researchers monitored seven Arabian mares throughout gestation using transrectal ultrasonography, recording nine biometric measurements (embryonic vesicle, crown-rump length, biparietal diameter, stomach diameter, chest depth, abdominal diameter, kidney length, eyeball diameter, and eye lens length) alongside key developmental milestones from insemination to parturition. Most biometric parameters showed strong linear correlations with gestational age, enabling accurate fetal age estimation, whilst fetal sex determination proved feasible from day 56 onwards but achieved optimal accuracy of 98% and practical applicability in 64.9% of cases between days 105 and 133 of gestation. For practitioners managing Arabian mares, these findings establish a species-specific reference frame for monitoring normal fetal development, detecting growth abnormalities, and planning breeding interventions; the identified window for fetal sexing (days 105–133) provides a reliable timeframe for sex determination when early knowledge is required for management or breeding decisions. Incorporating these ultrasonographic protocols into routine reproductive monitoring offers farriers, veterinarians, and stud managers evidence-based tools to enhance herd health outcomes and breeding efficiency.
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Practical Takeaways
- •Use transrectal ultrasonography between days 105-133 of gestation for most accurate fetal sex determination in Arabian mares (98% accuracy)
- •Multiple biometric parameters (biparietal diameter, stomach diameter, chest depth, abdominal diameter, eyeball diameter) reliably predict gestational age, useful for monitoring pregnancy progression and predicting parturition timing
- •Establish baseline ultrasound milestones in your breeding program: vesicle at day 10, embryo proper at day 21, and ossification beginning at day 57 to identify pregnancies at risk early
Key Findings
- •Embryonic vesicle, embryo proper, organization, and ossification were first detected at days 10.3, 21.3, 33.6, and 57.7 respectively in Arabian horses
- •Biometric parameters (EV, BIP, STD, CHD, ABD, EBD) showed strong linear correlations with gestational age (P < 0.0001) except CRL, ELL, and KDL
- •Fetal sexing accuracy peaked at 98% with 64.9% applicability between days 105-133 of gestation
- •Ultrasonographic monitoring provides reliable assessment of fetal growth and gestational age estimation in Arabian horses