Assessment of fetal development during mid and late term pregnancies by standard B-Mode ultrasonography in Shetland ponies.
Authors: Wagner Lisa-Hélène, Aurich Jörg, Claaßen Svenja, Melchert Maria, Kaps Martim, Aurich Christine
Journal: Journal of equine veterinary science
Summary
# Editorial Summary This research addresses a notable gap in equine reproductive ultrasound by establishing fetal biometric reference data for Shetland ponies, a breed for which no standardised growth charts previously existed despite their widespread use in breeding programmes. Wagner and colleagues used serial transrectal and transabdominal ultrasonography from day 101 of pregnancy onwards in five Shetland mares to measure multiple fetal parameters including aortic diameter, eye diameter, combined rib and intercostal distance (CRID), gastric dimensions, and cardiac morphology, alongside observations of fetal activity and organ differentiation. Among the parameters assessed, fetal CRID emerged as the most reliable predictor of gestational age (±13.6 days accuracy), whilst aortic diameter proved most accurate for estimating days remaining to parturition (±16.2 days), both with clinically acceptable margins of error. These findings provide practitioners with evidence-based ultrasound reference standards essential for pregnancy management in this miniature breed, enabling more precise monitoring of fetal development and earlier detection of abnormalities that might necessitate intervention. The establishment of breed-specific growth charts will improve clinical decision-making for farriers, veterinarians and stud managers working with Shetland ponies, whilst the methodology provides a template for similar investigations in other underrepresented equine breeds.
Read the full abstract on PubMed
Practical Takeaways
- •Veterinarians managing Shetland pony pregnancies now have breed-specific ultrasound reference data to better estimate gestational age and predict parturition timing, improving pregnancy management in this small horse breed
- •Transabdominal and transrectal ultrasonography using standard B-mode can reliably assess fetal development in Shetland mares; CRID and aortic diameter are the most clinically useful parameters for timing predictions
- •These reference charts fill a critical gap for small horse breed practitioners who previously lacked validated biometric standards beyond those developed for larger riding horses and large ponies
Key Findings
- •Fetal combined rib and intercostal distance (CRID) was the best predictor of gestational age with ±13.6 days accuracy in Shetland mares
- •Fetal aortic diameter was the most accurate parameter for predicting days until parturition with ±16.2 days accuracy
- •Reference biometric data for fetal development in small horse breeds (Shetland ponies) were established starting from day 101 of pregnancy
- •Multiple ultrasonographic parameters including eye diameter, stomach dimensions, and heart morphology were successfully assessed and documented during mid and late term pregnancy