FREE SHIPPING over $40
OVER 9000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Home / Equine Research Bank / Equine Vet J / Fetal morphological features and abnormalities associated wi...
Equine veterinary journal2020; 53(3); 530-541; doi: 10.1111/evj.13340

Fetal morphological features and abnormalities associated with equine early pregnancy loss.

Abstract: Early pregnancy loss (EPL) occurs in approximately 8% of equine pregnancies, although the aetiology is mostly unknown and embryonic/fetal morphological abnormalities associated with EPL are not defined. Objective: To compare the morphology of EPL to clinically normal embryos/fetuses and previously described embryonic/fetal developmental milestones. To identify morphological abnormalities associated with equine EPL. Methods: Observational case-control study. Methods: Embryos/fetuses were obtained from clinically normal Thoroughbred and pony pregnancies (n = 11) and following EPL from Thoroughbred mares (n = 27). The crown-rump length (CRL) of embryos/fetuses was measured and macroscopic morphology and developmental age were determined independently by three blinded examiners. Sagittal sections of EPL (n = 13) and control (n = 6) embryos/fetuses were assessed microscopically. Fisher's exact test was used to determine significance (P < .05) and correlations were expressed by Pearson coefficient. Results: Age and CRL were strongly positively correlated in clinically normal Thoroughbred and reference (n = 15, R = .9 (95% CI: 0.8-1.0), R  = .9, P < .0001) but not EPL embryos/fetuses (n = 19, R = .1 (95% CI: -0.4 to 0.5), R  = .01, P = .75). Relative to controls, the CRL of EPL embryos/fetuses was smaller, with evidence of intrauterine growth retardation (IUGR) in 3/8 fetuses assessed. In 9/13 EPL embryos/fetuses, nonspecific neural tissue alterations were identified including disruption of developing pros-, mes- and rhombencephalon and the presence of haemosiderin, indicating premortem haemorrhage. Failed neural tube closure was identified in 1/13 EPL embryos/fetuses. Subcutaneous haemorrhage was present in 14/27 EPL embryos/fetuses. Conclusions: Autolysis significantly affected 15/27 EPL embryos/fetuses, excluding them from complete assessment. The IUGR reference cut-off values were based on a small number of controls. Conclusions: Morphological features associated with equine EPL were a mismatch between embryonic/fetal size and age, and alterations of the developing neural tissue and localised subcutaneous haemorrhage. Failed neural tube closure was confirmed as a rare specific abnormality.
© 2020 The Authors. Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
Get Full Text
Publication Date: 2020-09-19 PubMed ID: 32869365DOI: 10.1111/evj.13340Google 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.

This research investigates the morphological features and abnormalities linked to early pregnancy loss (EPL) in horses. It sets out to compare the anatomy of normal embryos and those affected by EPL while also identifying any irregularities connected to EPL.

Research Methodology

  • The study conducted an observational case-control study to compare equine embryos from clinically normal pregnancies with those from pregnancies which ended in early pregnancy loss (EPL).
  • Embryos were collected from both Thoroughbred and pony breeds, with 11 representing normal pregnancies and 27 from EPL pregnancies.
  • The size of the embryos was determined using a measure referred to as crown-rump length (CRL), and macroscopic morphology and developmental age were evaluated by three separate examiners who were not informed of the origins of the specimens.
  • The researchers also conducted microscopic assessments on sagittal sections of 13 EPL and 6 control embryos/fetuses.
  • The results were analyzed using Fisher’s exact test and any correlations expressed by the Pearson coefficient.

Research Findings

  • The study found a strong correlation in the developmental age and the crown-rump length (CRL) of normal embryos compared to the reference, but this correlation did not exist for EPL embryos.
  • In the EPL group, it was noted that their CRL measurements were smaller and showed signs of intrauterine growth retardation (IUGR) in approximately 3 of the 8 fetuses that were assessed.
  • The researchers also identified nonspecific alterations in the neural tissue, disruption in different sections of the developing brain (pros-, mes-, and rhombencephalon) and the presence of haemosiderin, implying pre-mortem hemorrhage, in about 9 of the 13 EPL embryos.
  • Failure in neural tube closure was identified in only one out of the 13 EPL embryos, whereas subcutaneous hemorrhage was observed in 14 out of 27 EPL embryos.

Research Conclusions

  • The study made several important observations linking early pregnancy loss in horses with mismatches in embryonic/fetal size and age, neural tissue development disruptions, and localized subcutaneous hemorrhage.
  • A challenge faced during the research was that significant autolysis affected 15 of the 27 EPL embryos, preventing their complete assessment.
  • Also, the intrauterine growth retardation (IUGR) reference values were based on a small number of controls, which might limit the conclusiveness of these findings.

Cite This Article

APA
Kahler A, McGonnell IM, Smart H, Kowalski AA, Smith KC, Wathes DC, de Mestre AM. (2020). Fetal morphological features and abnormalities associated with equine early pregnancy loss. Equine Vet J, 53(3), 530-541. https://doi.org/10.1111/evj.13340

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 53
Issue: 3
Pages: 530-541

Researcher Affiliations

Kahler, Anne
  • Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Hertfordshire, UK.
McGonnell, Imelda M
  • Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Hertfordshire, UK.
Smart, Harriette
  • Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Hertfordshire, UK.
Kowalski, Alycia A
  • Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Hertfordshire, UK.
  • Veterinary Care, University of Wisconsin, Madison, USA.
Smith, Ken C
  • Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, Hertfordshire, UK.
Wathes, D Claire
  • Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, Hertfordshire, UK.
de Mestre, Amanda M
  • Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Hertfordshire, UK.

MeSH Terms

  • Abortion, Veterinary
  • Animals
  • Case-Control Studies
  • Crown-Rump Length
  • Female
  • Fetal Growth Retardation / veterinary
  • Fetus
  • Gestational Age
  • Horse Diseases / etiology
  • Horses
  • Pregnancy

Grant Funding

  • VET/RS/250 / Thoroughbred Breeders Association
  • TBA/EPL/2018 / Thoroughbred Breeders Association
  • Horserace Betting Levy Board

References

This article includes 37 references
  1. Campbell M, Sandoe P. Welfare in horse breeding.. Vet Rec 2015;176:436-40.
  2. Bosh K, Powell D, Neibergs J, Shelton B, Zent W. Impact of reproductive efficiency over time and mare financial value on economic returns among Thoroughbred mares in central Kentucky.. Equine Vet J 2009;41:889-94.
  3. Rose B, Firth M, Morris B, Roach J, Wathes D, Verheyen K. Descriptive study of current therapeutic practices, clinical reproductive findings and incidence of pregnancy loss in intensively managed thoroughbred mares.. Anim Reprod Sci 2018;188:74-84.
  4. Hanlon D, Stevenson M, Evans M, Firth E. Reproductive performance of Thoroughbred mares in the Waikato region of New Zealand: 1. Descriptive analyses.. N Z Vet J 2012;60:329-34.
  5. Morris LH, Allen WR. Reproductive efficiency of intensively managed Thoroughbred mares in Newmarket.. Equine Vet J 2002;34:51-60.
  6. Allen WR, Brown L, Wright M, Wilsher S. Reproductive efficiency of Flatrace and National Hunt Thoroughbred mares and stallions in England.. Equine Vet J 2007;39:438-45.
  7. Nath L, Anderson G, McKinnon A. Reproductive efficiency of Thoroughbred and Standardbred horses in north-east Victoria.. Aust Vet J 2010;88:169-75.
  8. Miyakoshi D, Shikichi M, Ito K, Iwata K, Okai K, Sato F. Factors influencing the frequency of pregnancy loss among thoroughbred mares in Hidaka, Japan.. J Equine Vet Sci 2012;32:552-7.
  9. de Mestre A, Rose B, Chang Y, Wathes D, Verheyen K. Multivariable analysis to determine risk factors associated with early pregnancy loss in thoroughbred broodmares.. Theriogenology 2019;124:18-23.
  10. de Mestre A. Reproductive failure in horses: identifying the problem.. Vet Rec 2013;172:42-3.
  11. Hamstead L, Chang Y-M, Crowhurst J, Wise Z, Ricketts S, de Mestre AM. Retrospective study of early pregnancy loss in Thoroughbred mares.. Equine Vet J 2012;44(S42):2-18.
  12. Poland BJ, Miller J, Harris M, Livingston J. Spontaneous abortion. A study of 1,961 women and their conceptuses.. Acta Obstet Gynecol Scand Suppl 1981;102:1-32.
  13. Byrne J, Warburton D, Kline J, Blanc W, Stein Z. Morphology of early fetal deaths and their chromosomal characteristics.. Teratology 1985;32:297-315.
  14. Vogt C, Blaas H, Salvesen K, Eik-Nes S. Comparison between prenatal ultrasound and postmortem findings in fetuses and infants with developmental anomalies.. Ultrasound Obstet Gynecol 2012;39:666-72.
  15. Acker D, Curran S, Bersu E, Ginther O. Morphologic stages of the equine embryo proper on days 17 to 40 after ovulation.. Am J Vet Res 2001;62:1358-64.
  16. 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.
  17. Jenner F, Närväinen J, de Ruijter-Villani M, Stout T, van Weeren P, Brama P. Magnetic resonance microscopy atlas of equine embryonic development.. Equine Vet J 2014;46:210-5.
  18. Allen WR, Wilsher S. A review of implantation and early placentation in the mare.. Placenta 2009;30:1005-15.
  19. Stout TAE, Troedsson MHT. Report of the Havemeyer Foundation Workshop on equine implantation: is early pregnancy loss the only important potential consequence of disturbed preimplantation development?. Equine Vet J 2015;47:381-3.
  20. Rose B, Cabrera-Sharp V, Firth M, Barrelet F, Bate S, Cameron IJ. A method for isolating and culturing placental cells from failed early equine pregnancies.. Placenta 2016;38:107-11.
  21. Rowlands I, Allen W, Rossdale P. Equine reproduction III. Proceedings of the Third International Symposium on Equine Reproduction. University of Sydney, January 1982.. J Reprod Fertil 1982;(Suppl 32):1-660.
  22. Robles M, Peugnet PM, Valentino SA, Dubois C, Dahirel M, Aubrière MC. Placental alterations in structure and function in intra-uterine growth-retarded horses.. Equine Vet J 2018;50:405-14.
  23. Genest DR, Singer DB. Estimating the time of death in stillborn fetuses: III. External fetal examination; a study of 86 stillborns.. Obstet Gynecol 1992;80:593-600.
  24. Bukowski R, Hansen NI, Pinar H, Willinger M, Reddy UM, Parker CB. Altered fetal growth, placental abnormalities, and stillbirth.. PLoS One 2017;12:e0182874.
  25. Balayla J, Desilets J, Shrem G. Placenta previa and the risk of intrauterine growth restriction (IUGR): a systematic review and meta-analysis.. J Perinat Med 2019;47:577-84.
  26. Khoury MJ, Erickson JD, Cordero JF, McCarthy BJ. Congenital malformations and intrauterine growth retardation: a population study.. Pediatrics 1988;82:83-90.
  27. Peugnet PM, Wimel L, Duchamp G, Sandersen C, Camous S, Guillaume D. Enhanced or reduced fetal growth induced by embryo transfer into smaller or larger breeds alters post-natal growth and metabolism in pre-weaning horses.. PLoS One 2014;9:e102044.
  28. 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 2002;123:445-53.
  29. Robles M, Dubois C, Gautier C, Dahirel M, Guenon I, Bouraima-Lelong H. Maternal parity affects placental development, growth and metabolism of foals until 1 year and a half.. Theriogenology 2018;108:321-30.
  30. Perez-Garcia V, Fineberg E, Wilson R, Murray A, Mazzeo CI, Tudor C. Placentation defects are highly prevalent in embryonic lethal mouse mutants.. Nature 2018;555:463-8.
  31. Allen WR. The diagnosis and handling of early gestational abnormalities in the mare.. Anim Reprod Sci 1992;28:31-8.
  32. Sadler T. Embryology of neural tube development.. Am J Med Genet 2005;135C:2-8.
  33. Byrne J, Warburton D, Opitz JM, Reynolds JF. Neural tube defects in spontaneous abortions.. Am J Med Genet 1986;25:327-33.
  34. Kasarskis A, Manova K, Anderson K. A phenotype-based screen for embryonic lethal mutations in the mouse.. Proc Natl Acad Sci 1998;95:7485-90.
  35. Ursell PC, Byrne JM, Strobino BA. Significance of cardiac defects in the developing fetus: a study of spontaneous abortuses.. Circulation 1985;72:1232-6.
  36. Ma Y, Pei Y, Yin C, Jiang Y, Wang J, Li X. Subchromosomal anomalies in small for gestational-age fetuses and newborns.. Arch Gynecol Obstet 2019;300:633-9.
  37. Lopez-Escobar B, Wlodarczyk BJ, Caro-Vega J, Lin Y, Finnell RH, Ybot-Gonzalez P. The interaction of maternal diabetes with mutations that affect folate metabolism and how they affect the development of neural tube defects in mice.. Dev Dyn 2019;248:900-17.

Citations

This article has been cited 4 times.
  1. Okada CTC, Kaps M, Perez Quesada J, Gautier C, Aurich J, Aurich C. Diestrous Ovulations in Pregnant Mares as a Response to Low Early Postovulatory Progestogen Concentration. Animals (Basel) 2020 Nov 30;10(12).
    doi: 10.3390/ani10122249pubmed: 33266083google scholar: lookup
  2. Lawson JM, Salem SE, Miller D, Kahler A, van den Boer WJ, Shilton CA, Sever T, Mouncey RR, Ward J, Hampshire DJ, Foote AK, Bryan JS, Juras R, Pynn OD, Davis BW, Bellone RR, Raudsepp T, de Mestre AM. Naturally occurring horse model of miscarriage reveals temporal relationship between chromosomal aberration type and point of lethality. Proc Natl Acad Sci U S A 2024 Aug 13;121(33):e2405636121.
    doi: 10.1073/pnas.2405636121pubmed: 39102548google scholar: lookup
  3. Li L, Li S, Ma H, Akhtar MF, Tan Y, Wang T, Liu W, Khan A, Khan MZ, Wang C. An Overview of Infectious and Non-Infectious Causes of Pregnancy Losses in Equine. Animals (Basel) 2024 Jul 2;14(13).
    doi: 10.3390/ani14131961pubmed: 38998073google scholar: lookup
  4. Morales-Vázquez MM, Meza-Serrano E, Lara-Pereyra I, Acuña-González RJ, Alonso-Morales R, Hayen-Valles S, Boeta AM, Zarco L, Lozano-Cuenca J, López-Canales JS, Flores-Herrera H. Equine Placentitis in Mares Induces the Secretion of Pro-Inflammatory Cytokine eIL-1β and the Active Extracellular Matrix Metalloproteinase (MMP)-9. Vet Sci 2023 Aug 22;10(9).
    doi: 10.3390/vetsci10090532pubmed: 37756054google scholar: lookup
Subscribe to our newsletter
Join 99,001 horse owners like you who receive our email updates on horse health and nutrition.