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Equine veterinary education2015; 26(6); 322-327; doi: 10.1111/eve.12182

Embryo transfer in competition horses: Managing mares and expectations.

Abstract: Embryo transfer (ET) is an accepted and successful technique for obtaining foals from mares without interrupting their competition careers. Recent research, however, suggests that the potential of factors including heat, exercise, repeated embryo flushing and repeated manipulation of the reproductive cycle using exogenous hormones to have a negative impact on fertility may have been underestimated. This paper reviews the evidence base for involvement of these factors in repeated failures to recover embryos from nongeriatric competition mares without obvious clinical or pathological indications of reproductive abnormalities. It concludes that, for some mares at least, a cessation of exercise for the periovulatory period and the period between ovulation and embryo flushing, combined with careful management of flushing-induced endometritis, and minimal hormonal manipulation of the reproductive cycle, may be necessary to optimise embryo recovery rates. Mare owners may have been encouraged to request ET for their mares following high-profile examples in the media of elite mares that have produced foals by ET whilst competing. The veterinarian should educate mare owners about the multiple factors that may affect the chances of recovering an embryo from their mares, and should manage the expectations of mare owners so that they do not approach ET programmes in the expectation that there will be no disruption to their training and competition plans.
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Publication Date: 2015-05-16 PubMed ID: 25977596PubMed Central: PMC4427944DOI: 10.1111/eve.12182Google Scholar: Lookup
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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 focuses on the impact of various aspects like heat, exercise, repeated embryo flushing, and hormonal manipulations on the fertility of competition mares during embryo transfer (ET). It suggests that lack of understanding about these factors could be why embryos are not recovered from otherwise healthy competition mares. The study recommends reducing exercise, careful management of endometritis, and minimal hormonal interference with the reproductive cycle for higher embryo recovery rates.

About Embryo Transfer in Horses

  • Embryo transfer (ET) is a widely accepted practice in horse breeding which allows for a mare to continue her competition career whilst being able to have her foals.
  • However, this study brings forth the potential of factors such as heat, exercise, repeated embryo flushing (removal of the fertilized egg or embryo from the mare for transfer into a surrogate mother), and repeated hormonal manipulation to have a negative impact on the mare’s fertility.

Critical Review of the Factors Affecting Fertility

  • The research paper particularly focuses on nongeriatric competition mares which showed no overt clinical or pathological indications of reproductive abnormalities, but yet failed to recover embryos during ET.
  • It propounds that the fertility issues might be associated with the intense training and competition schedules that these mares are subjected to, including the periods around ovulation and embryo flushing.
  • Additionally, the paper highlights the possible role of indiscriminate and frequent hormonal manipulation of the mares’ reproductive cycle in affecting their fertility.

Recommendations for Successful Embryo Transfer

  • The study suggests that lessening exercise for the mare during the periovulatory period (around ovulation) and the period between ovulation and embryo flushing could be beneficial.
  • It further recommends managing embryo flushing-induced endometritis (inflammation of the inner lining of the uterus), and reducing the unnecessary manipulation of the reproductive cycle using hormones.
  • These suggestions, the research argues, might be effective in enhancing the chances of successful embryo recovery from competition mares.

Advising Mare Owners

  • The research concludes with the importance of educating mare owners about these factors that potentially impact the success of ET.
  • Veterinarians are encouraged to manage the expectations of horse owners so they understand that the ET process might require some changes to the usual training and competition schedules of their mares.

Cite This Article

APA
Campbell ML. (2015). Embryo transfer in competition horses: Managing mares and expectations. Equine Vet Educ, 26(6), 322-327. https://doi.org/10.1111/eve.12182

Publication

Equine veterinary education
ISSN: 0957-7734
NlmUniqueID: 9885274
Country: England
Language: English
Volume: 26
Issue: 6
Pages: 322-327

Researcher Affiliations

Campbell, M L H
  • Department of Production and Population Health, The Royal Veterinary College North Mymms, Hertfordshire, UK.

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Citations

This article has been cited 8 times.
  1. Mahmood K, Hassan M, Channa AA, Ghafoor A, Riaz A. Comparative analysis of breeding patterns and reproductive efficiency of mares in subtropical conditions of Pakistan. Vet Med Sci 2024 Sep;10(5):e1582.
    doi: 10.1002/vms3.1582pubmed: 39132854google scholar: lookup
  2. Alkhadrawy JMH, Aboelmaaty AM, Abou-Ahmed MM, Ghallab AM. Effect of breeding season and age on follicular dynamics and hemodynamics in embryo donor mares subjected to luteolysis after embryo flushing. Open Vet J 2024 Mar;14(3):852-865.
    doi: 10.5455/OVJ.2024.v14.i3.13pubmed: 38682132google scholar: lookup
  3. Cardona-García M, Jiménez-Escobar C, Ferrer MS, Maldonado-Estrada JG. Follicular Dynamics and Pregnancy Rates during Foal Heat in Colombian Paso Fino Mares Bred under Permanent Grazing. Animals (Basel) 2024 Feb 29;14(5).
    doi: 10.3390/ani14050760pubmed: 38473144google scholar: lookup
  4. Mahmood K, Ali Channa A, Ghafoor A, Riaz A. Factors affecting the efficiency of equine embryo transfer (EET) in polo mares under subtropical conditions of Pakistan. PLoS One 2024;19(2):e0298066.
    doi: 10.1371/journal.pone.0298066pubmed: 38346056google scholar: lookup
  5. Rajabi-Toustani R, Tsogtgerel M, Gao Y, Li C, Sakato M, Haneda S, Cheong SH, Nambo Y. First Kiso pony foal produced via transfer of long-distance shipped fresh embryo to Hokkaido native pony. J Reprod Dev 2023 Apr 3;69(2):125-128.
    doi: 10.1262/jrd.2022-125pubmed: 36724993google scholar: lookup
  6. Segabinazzi LGTM, Andrade LRP Jr, Alvarenga MA, Dell'Aqua JA Jr, Canisso IF. Use of Intravaginal Progesterone-Releasing Device Results in Similar Pregnancy Rates and Losses to Long-Acting Progesterone to Synchronize Acyclic Embryo Recipient Mares. Vet Sci 2021 Sep 10;8(9).
    doi: 10.3390/vetsci8090190pubmed: 34564584google scholar: lookup
  7. Hannan MA, Haneda S, Murata K, Takeuchi S, Cheong SH, Nambo Y. Birth of first foals through embryo transfer after artificial insemination using frozen semen in Japan. J Reprod Dev 2020 Apr 10;66(2):193-197.
    doi: 10.1262/jrd.2019-117pubmed: 31983706google scholar: lookup
  8. Hannan MA, Haneda S, Itami Y, Wachi S, Saitoh T, Cheong SH, Nambo Y. Successful embryo transfer from Hokkaido native pony after artificial insemination with frozen semen. J Vet Med Sci 2019 Feb 19;81(2):241-244.
    doi: 10.1292/jvms.18-0414pubmed: 30606892google scholar: lookup
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