FREE SHIPPING over $40
OVER 9000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Home / Equine Research Bank / Front Vet Sci / Fetometry in Arabian horses.
Frontiers in veterinary science2025; 12; 1689769; doi: 10.3389/fvets.2025.1689769

Fetometry in Arabian horses.

Abstract: This study aimed to monitor intrauterine fetal growth, establish predictive equations for gestational age estimation, and determine the optimal period for fetal sexing in Arabian horses using ultrasonography. Unassigned: Seven Arabian mares were monitored from insemination to parturition using transrectal ultrasonography. The following fetal and embryonic parameters were measured: embryonic vesicle (EV), crown-rump length (CRL), biparietal diameter (BIP), stomach diameter (STD), chest depth (CHD), abdominal diameter (ABD), kidney length (KDL), eyeball diameter (EBD), and eye lens length (ELL). Key developmental milestones were recorded, including detection of the EV, embryo proper, organization, and ossification. Unassigned: The EV, embryo proper, organization, and ossification were visualized at days 10.3 ± 0.5, 21.3 ± 1.3, 33.6 ± 2.0, and 57.7 ± 3.5, respectively. All biometric parameters, except CRL, ELL, and KDL, exhibited strong linear correlations with gestational age (P < 0.0001). Fetal sexing was feasible between days 56 and 161, with maximum accuracy (98%) and applicability (64.9%) between days 105 and 133. Unassigned: Ultrasonographic monitoring provides reliable parameters for assessing fetal growth and estimating gestational age in Arabian horses. The period between days 105 and 133 of gestation represents the optimal window for accurate fetal sex determination. These findings enhance reproductive monitoring and breeding management practices in Arabian horse herds.
Copyright © 2025 Ali, Derar, Alaeyeari and Alharbi.
Get Full Text
Publication Date: 2025-10-23 PubMed ID: 41209474PubMed Central: PMC12588862DOI: 10.3389/fvets.2025.1689769Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This study used ultrasound to track fetal development in Arabian horses, create formulas to estimate how far along the pregnancy is, and find the best time to determine the fetus’s sex.
  • The research identified key fetal growth milestones and the optimal timeframe for reliable fetal sexing, improving pregnancy monitoring and breeding decisions for Arabian horse breeders.

Introduction and Objectives

  • The study focused on fetometry, which is the measurement of fetal size and growth during pregnancy.
  • Specific aims included:
    • Monitoring intrauterine fetal growth in Arabian horses using ultrasonography.
    • Developing predictive equations to estimate gestational age based on fetal measurements.
    • Determining the best gestational period for accurately identifying fetal sex.

Methods

  • Subjects:
    • Seven Arabian mares were studied from insemination until foaling.
  • Monitoring technique:
    • Transrectal ultrasonography was used for fetal visualization and measurement.
  • Parameters measured included:
    • Embryonic Vesicle (EV) size
    • Crown-Rump Length (CRL)
    • Biparietal Diameter (BIP) – width of the fetal head
    • Stomach Diameter (STD)
    • Chest Depth (CHD)
    • Abdominal Diameter (ABD)
    • Kidney Length (KDL)
    • Eyeball Diameter (EBD)
    • Eye Lens Length (ELL)
  • Key developmental stages recorded:
    • Detection of embryonic vesicle
    • Appearance of embryo proper
    • Organ development (organization)
    • Bone formation (ossification)

Results

  • Timing of visualizing developmental milestones:
    • Embryonic vesicle first seen at 10.3 ± 0.5 days post-insemination.
    • Embryo proper appeared at 21.3 ± 1.3 days.
    • Organ organization observed at 33.6 ± 2.0 days.
    • Ossification started at 57.7 ± 3.5 days.
  • Correlations with gestational age:
    • Most biometric parameters showed strong linear correlations with gestational age (highly significant, P < 0.0001).
    • Exceptions where correlations were not strong included CRL, ELL, and KDL.
  • Fetal sexing:
    • Possible from day 56 to day 161 of gestation.
    • Highest accuracy (98%) and best applicability (64.9% of cases) occurred between days 105 and 133.

Conclusions and Implications

  • Ultrasonography is a reliable tool for tracking fetal development in Arabian horses and estimating how far along the pregnancy is using biometric measurements.
  • The study establishes a timeline of key fetal growth and development stages that can be monitored noninvasively.
  • The most effective fetal sex determination window is days 105 to 133 of pregnancy, enabling breeders to make informed decisions earlier in gestation.
  • These findings support enhanced reproductive management in Arabian horse breeding programs by providing objective measures for pregnancy monitoring and sex prediction.

Cite This Article

APA
Ali A, Derar DR, Alaeyeari AA, Alharbi YM. (2025). Fetometry in Arabian horses. Front Vet Sci, 12, 1689769. https://doi.org/10.3389/fvets.2025.1689769

Publication

Frontiers in veterinary science
ISSN: 2297-1769
NlmUniqueID: 101666658
Country: Switzerland
Language: English
Volume: 12
Pages: 1689769
PII: 1689769

Researcher Affiliations

Ali, Ahmed
  • Department of Clinical Sciences, College of Veterinary Medicine, Qassim University, Buraydah, Saudi Arabia.
Derar, Derar R
  • Department of Clinical Sciences, College of Veterinary Medicine, Qassim University, Buraydah, Saudi Arabia.
Alaeyeari, Ahmad A
  • Department of Clinical Sciences, College of Veterinary Medicine, Qassim University, Buraydah, Saudi Arabia.
Alharbi, Yousef M
  • Department of Medical Biosciences, College of Veterinary Medicine, Qassim University, Buraydah, Saudi Arabia.

Conflict of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

References

This article includes 38 references
  1. Bucca S, Fogarty U, Collins A, Small V. Assessment of feto-placental well-being in the mare from mid-gestation to term: transrectal and transabdominal ultrasonographic features.. Theriogenology (2005) 64:542–57.
    doi: 10.1016/j.theriogenology.2005.05.011pubmed: 15993936google scholar: lookup
  2. Renaudin C, Wensley F, Morgan J, Cassano J, Spriet M. Transrectal ultrasonographic assessment of the fetal proximal phalanx: a new tool to assess fetal age and bone development in horses.. Theriogenology (2024) 226:167–72.
    doi: 10.1016/j.theriogenology.2024.06.010pubmed: 38905931google scholar: lookup
  3. Ali A, Alamaary M, Al-Sobayil F. Reproductive performance of Arab mares in the Kingdom of Saudi Arabia.. Tierarztliche Praxis Ausgabe G, Grosstiere/Nutztiere (2014) 42:145–9.
    pubmed: 24920087
  4. Khan IU, Khairullah AR, Khan AY, Rehman AU, Mustofa I. Strategic approaches to improve equine breeding and stud farm outcomes.. Vet World (2025) 18:311–28.
    doi: 10.14202/vetworld.2025.311-328pmc: PMC11963589pubmed: 40182817google scholar: lookup
  5. Elliott C, Morton J, Chopin J. Factors affecting foal birth weight in thoroughbred horses.. Theriogenology (2009) 71:683–9.
    doi: 10.1016/j.theriogenology.2008.09.041pubmed: 18980778google scholar: lookup
  6. Klewitz J, Struebing C, Rohn K, Goergens A, Martinsson G, Orgies F. Effects of age, parity, and pregnancy abnormalities on foal birth weight and uterine blood flow in the mare.. Theriogenology (2015) 83:721–9.
    doi: 10.1016/j.theriogenology.2014.11.007pubmed: 25483867google scholar: lookup
  7. Meirelles MG, Veras MM, Alonso MA, de Fátima Guimarães C, Nichi M, Fernandes CB. Influence of maternal age and parity on placental structure and foal characteristics from birth up to 2 years of age.. J Equine Vet Sci (2017) 56:68–79.
    doi: 10.1016/j.jevs.2017.03.226google scholar: lookup
  8. . Arabian breed.. (2025).
  9. Ali A, Derar DR, Abdel-Razek AK. Ultrasonography for the detection of pregnancy and study of embryonic and fetal development in camels, buffaloes, and sheep: techniques, equations, and limitations.. Anim Reprod Sci (2024) 268:107566.
    doi: 10.1016/j.anireprosci.2024.107566pubmed: 39089168google scholar: lookup
  10. Del'Aguila-Silva P, Cirino Dos Santos F, Correia Santos VJ, Rodrigues Simões AP, Ramirez Uscategui RA, Padilha-Nakaghi LC. B-mode ultrasound and ecobiometric parameters to assess embryonic and fetal development and estimate gestational age in goats.. Theriogenology (2021) 175:123–33.
    doi: 10.1016/j.theriogenology.2021.09.002pubmed: 34544011google scholar: lookup
  11. Krog CH, Agerholm JS, Nielsen SS. Fetal age assessment for Holstein cattle.. PLoS One (2018) 13:e0207682.
    doi: 10.1371/journal.pone.0207682pmc: PMC6242369pubmed: 30452469google scholar: lookup
  12. Succu S, Contu E, Bebbere D, Gadau SD, Falchi L, Nieddu SM. Fetal growth and osteogenesis dynamics during early development in the ovine species.. Animals (2023) 13:773.
    doi: 10.3390/ani13050773pmc: PMC10000038pubmed: 36899630google scholar: lookup
  13. Hendriks WK, Colenbrander B, van der Weijden GC, Stout TA. Maternal age and parity influence ultrasonographic measurements of fetal growth in Dutch warmblood mares.. Anim Reprod Sci (2009) 115:110–23.
    doi: 10.1016/j.anireprosci.2008.12.014pubmed: 19157730google scholar: lookup
  14. Murase H, Endo Y, Tsuchiya T, Kotoyori Y, Shikichi M, Ito K. Ultrasonographic evaluation of equine fetal growth throughout gestation in normal mares using a convex transducer.. J Vet Med Sci (2014) 76:947–53.
    doi: 10.1292/jvms.13-0259pmc: PMC4143655pubmed: 24662520google scholar: lookup
  15. Lanci A, Castagnetti C, Ranciati S, Sergio C, Mariella J. A regression model including fetal orbit measurements to predict parturition in Standardbred mares with normal pregnancy.. Theriogenology (2019) 126:153–8.
    doi: 10.1016/j.theriogenology.2018.12.020pubmed: 30553975google scholar: lookup
  16. Renaudin CD, Kass PH, Bruyas JF. Prediction of gestational age based on foetal ultrasonographic biometric measurements in light breed horses. Reprod Domestic Animals = Zuchthygiene (2022) 57:743–53.
    doi: 10.1111/rda.14116pubmed: 35342998google scholar: lookup
  17. Curran S, Ginther OJ. Ultrasonic diagnosis of equine fetal sex by location of the genital tubercle. J Equine Vet Sci (1989) 9:77–83.
    doi: 10.1016/S0737-0806(89)80032-2google scholar: lookup
  18. Renaudin CD, Gillis CL, Tarantal AF. Transabdominal ultrasonographic determination of fetal gender in the horse during mid-gestation. Equine Vet J (1999) 31:483–7.
    doi: 10.1111/j.2042-3306.1999.tb03855.xpubmed: 10596929google scholar: lookup
  19. Potter SJ, Erdody ML, Bamford NJ, Knowles EJ, Menzies-Gow N, Morrison PK. Development of a body condition index to estimate adiposity in ponies and horses from morphometric measurements. Equine Vet J (2024) 56:299–308.
    doi: 10.1111/evj.13975pubmed: 37537987google scholar: lookup
  20. Ali A, Fahmy S. Ultrasonographic fetometry and determination of fetal sex in buffaloes. Anim Reprod Sci (2008) 106:90–9.
    doi: 10.1016/j.anireprosci.2007.04.010pubmed: 17544605google scholar: lookup
  21. Ali A, Al-Sobayil F, Derar R, El-Tookhy O. Ultrasonographic fetometry and prenatal fetal sex assessment in camels. Theriogenology (2013) 80:609–18.
    doi: 10.1016/j.theriogenology.2013.05.028pubmed: 23830233google scholar: lookup
  22. Allen WR, Wilsher S, Turnbull C, Stewart F, Ousey J, Rossdale PD. Influence of maternal size on placental, fetal and postnatal growth in the horse. I. Development in utero. Reproduction (Cambridge, England) (2002) 123:445–53.
    pubmed: 11882022
  23. Heidler B, Aurich JE, Pohl W, Aurich C. Body weight of mares and foals, estrous cycles and plasma glucose concentration in lactating and non-lactating Lipizzaner mares. Theriogenology (2004) 61:883–93.
    doi: 10.1016/s0093-691x(03)00279-6pubmed: 14757474google scholar: lookup
  24. Pagan JD, Phethean E, Caddel S, McFaull M, Bonner P, Nowara D. Factors affecting birth weights in thoroughbred foals born in Kentucky, United Kingdom, and Australia. J Equine Vet Sci (2023) 124:104419.
    doi: 10.1016/j.jevs.2023.104419google scholar: lookup
  25. Hacan Ö, Tekerli M, Çinkaya S, Demirtaş M. Genetic trends in body measurements at birth for Arabian horse in Türkiye. Arch Anim Breed (2024) 67:561–70.
    doi: 10.5194/aab-67-561-2024google scholar: lookup
  26. Fernandes CB, Meirelles MG, Guimaraes CF, Nichi M, Affonso FJ, Fonte JS. Which paternal, maternal and placental parameters influence foal size and vitality?. J Equine Vet Sci (2014) 34:225–7.
    doi: 10.1016/j.jevs.2013.10.161google scholar: lookup
  27. Peugnet P, Robles M, Wimel L, Tarrade A, Chavatte-Palmer P. Management of the pregnant mare and long-term consequences on the offspring. Theriogenology (2016) 86:99–109.
    doi: 10.1016/j.theriogenology.2016.01.028pubmed: 26954944google scholar: lookup
  28. Ginther OJ. Physical activities and morphologic aspects of the equine fetus during days 40-150. J Equine Vet Sci (2022) 112:103891.
    doi: 10.1016/j.jevs.2022.103891pubmed: 35143928google scholar: lookup
  29. Renaudin CD, Gillis CL, Tarantal AF, Coleman DA. Evaluation of equine fetal growth from day 100 of gestation to parturition by ultrasonography. J Reprod Fertil Suppl (2000) 56:651–60.
    pubmed: 20681181
  30. Turner RM, McDonnell SM, Feit EM, Grogan EH, Foglia R. Real-time ultrasound measure of the fetal eye (vitreous body) for prediction of parturition date in small ponies. Theriogenology (2006) 66:331–7.
    doi: 10.1016/j.theriogenology.2005.11.019pubmed: 16426670google scholar: lookup
  31. Nervo T, Bertero A, Poletto M, Pregel P, Leone R, Toffoli V. Field ultrasound evaluation of some gestational parameters in jennies.. Theriogenology (2019) 126:95–105.
    doi: 10.1016/j.theriogenology.2018.11.023pubmed: 30544000google scholar: lookup
  32. Franciolli AL, Cordeiro BM, da Fonseca ET, Rodrigues MN, Sarmento CA, Ambrosio CE. Characteristics of the equine embryo and fetus from days 15 to 107 of pregnancy.. Theriogenology (2011) 76:819–32.
    doi: 10.1016/j.theriogenology.2011.04.014pubmed: 21719090google scholar: lookup
  33. Rodrigues MN, Carvalho RC, Franciolli AL, Rodrigues RF, Rigoglio NN, Jacob JC. Prenatal development of the digestive system in the horse.. Anatom Rec (Hoboken, NJ: 2007) (2014) 297:1218–27.
    doi: 10.1002/ar.22929pubmed: 24778084google scholar: lookup
  34. Bucca S, De Oliveira IRS, Cunanan JC, Vinardell T, Troedsson MHT. Doppler indices of the equine fetal carotid artery throughout gestation.. Theriogenology (2020) 156:196–204.
    doi: 10.1016/j.theriogenology.2020.07.009pubmed: 32755719google scholar: lookup
  35. Lanci A, Ingrà L, Dondi F, Tomasello F, Teti G, Mariella J. Morphological study of equine amniotic compartment.. Theriogenology (2022) 177:165–71.
    doi: 10.1016/j.theriogenology.2021.10.019pubmed: 34710648google scholar: lookup
  36. Adams-Brendemuehl C, Pipers FS. Antepartum evaluations of the equine fetus.. J Reprod Fertil Suppl (1987) 35:565–73.
    pubmed: 3316646
  37. Ali A. Effect of gestational age and fetal position on the possibility and accuracy of ultrasonographic fetal gender determination in dairy cattle.. Reprod Domestic Animals = Zuchthygiene (2004) 39:190–4.
    doi: 10.1111/j.1439-0531.2004.00502.xpubmed: 15182296google scholar: lookup
  38. Curran S, Ginther OJ. Ultrasonic determination of fetal gender in horses and cattle under farm conditions.. Theriogenology (1991) 36:809–14.
    doi: 10.1016/0093-691x(91)90346-fpubmed: 16727049google scholar: lookup

Citations

This article has been cited 0 times.
Subscribe to our newsletter
Join 99,030 horse owners like you who receive our email updates on horse health and nutrition.