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Equine veterinary journal2024; 56(4); 726-734; doi: 10.1111/evj.14071

Success rates and factors influencing pregnancy outcome after 464 transvaginal ultrasound-guided twin reductions in the mare.

Abstract: Transvaginal ultrasound-guided aspiration (TUA) is used for post-fixation twin reduction in mares. However, there is limited information regarding factors that influence pregnancy outcome after TUA. Objective: To evaluate the effect of day of gestation on which TUA is performed, aspiration volume, puncture of the conceptus, medication administered before and after TUA, embryo location, mare age and parity and operator experience on pregnancy and foaling rates after TUA. Methods: Retrospective case series. Methods: Data were collected from case records of 464 TUAs performed by 14 operators in 422 mares diagnosed pregnant with dizygotic twins in two different facilities between 2010 and 2019. Pregnancy status was determined by ultrasonography at 5-7 days and 3-4 weeks after the TUA was performed. Subsequent pregnancy and foaling results were obtained by follow-up communication. The effects of mare, gestation- and TUA-related variables on pregnancy and foaling rates were analysed by the chi-square-test for homogeneity and Fisher's exact test and logistic regression. Results: TUA was performed between 21 and 82 days of gestation in unilaterally (267/359 [74.4%]) and bilaterally fixed (92/359 [25.6%]) twin pregnancies. A singleton pregnancy (218/381 [57.2%]), persistent twin pregnancy (60/381 [15.8%]), or the loss of both conceptuses (103/381 [27%]) was confirmed 5-7 days after TUA was performed. At 3-4 weeks post TUA 50.3% (163/324) of mares were diagnosed with a single viable pregnancy and 40.1% (127/317) went on to deliver a live single foal. TUA performed early in gestation (D 25-35) resulted in the birth of a live singleton foal in 49.3% (74/150) of mares. Conclusions: Missing retrospective data despite extensive follow-up. Conclusions: This is the first large scale study to demonstrate that acceptable pregnancy and foaling rates can be achieved in mares diagnosed with twins when TUA is performed early in gestation (<40 days).
© 2024 The Authors. Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
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Publication Date: 2024-02-14 PubMed ID: 38353172DOI: 10.1111/evj.14071Google Scholar: Lookup
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Summary

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The research article investigates the impact of various factors on the success of transvaginal ultrasound-guided aspirations (TUAs) carried out for reducing twin pregnancies in horses. It reveals that performing TUA early in the gestation process improves the likelihood of a successful single offspring birth.

Objective and Methods

  • The aim of the research was to determine the influence of different variables on the success of TUAs in managing twin pregnancies in mares. This included factors such as the specific day of gestation the TUA was performed, the volume of aspiration, whether the conceptus was punctured, the medication provided before and after the TUA, the location of the embryo, the mare’s age and parity and the experience level of the operator.
  • The methods involved gathering data from the case records of 464 TUAs carried out by 14 operators on 422 mares diagnosed with dizygotic twins across two facilities during 2010 and 2019.
  • Ultrasonography was used to determine the pregnancy status at two intervals—5-7 days and 3-4 weeks—after the TUA was carried out. Further information about pregnancy and foaling outcomes was obtained via follow-up communication.
  • The chi-square-test for homogeneity, Fisher’s exact test and logistic regression were used to analyze the effects of the mare, gestation, and TUA-related variables on pregnancy and foaling rates.

Results

  • The TUAs were performed between 21 and 82 days of gestation and resulted in singleton pregnancies in 57.2% of cases, persistent twin pregnancies in 15.8% of cases, and loss of both conceptuses in 27% of cases, as confirmed 5-7 days after the procedure.
  • Approximately 50.3% of mares were diagnosed with a single viable pregnancy 3-4 weeks post TUA, and 40.1% went on to deliver a live single foal.
  • The study found that performing the TUA during early gestation (Days 25-35) led to a live singleton birth in 49.3% of the mares.

Conclusions

  • The research study acknowledges the potential limitations of missing retrospective data despite extensive follow-up efforts.
  • This study is touted as the first extensive research demonstrating that satisfactory pregnancy and foaling rates can be achieved in mares diagnosed with twins, when TUAs are carried out early in the gestation phase.

Cite This Article

APA
Sielhorst J, Baade S, Neudeck KC, Tönissen A, Rohn K, Hollinshead F, Sieme H. (2024). Success rates and factors influencing pregnancy outcome after 464 transvaginal ultrasound-guided twin reductions in the mare. Equine Vet J, 56(4), 726-734. https://doi.org/10.1111/evj.14071

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 56
Issue: 4
Pages: 726-734

Researcher Affiliations

Sielhorst, Jutta
  • ReproTraining, Verl, Germany.
  • Unit for Reproductive Medicine-Clinic for Horses University of Veterinary Medicine Hanover, Foundation, Hanover, Germany.
Baade, Sophie
  • Unit for Reproductive Medicine-Clinic for Horses University of Veterinary Medicine Hanover, Foundation, Hanover, Germany.
  • Veterinary Clinic Karthaus, Duelmen, Germany.
Neudeck, Kim-Carolin
  • Veterinary Clinic Karthaus, Duelmen, Germany.
Tönissen, Anna
  • Unit for Reproductive Medicine-Clinic for Horses University of Veterinary Medicine Hanover, Foundation, Hanover, Germany.
Rohn, Karl
  • Institute of Biometry, Epidemiology and Information Processing, University of Veterinary Medicine Hanover, Foundation, Hanover, Germany.
Hollinshead, Fiona
  • College of Veterinary Medicine and Biomedical Science, Colorado State University, Fort Collins, Colorado, USA.
Sieme, Harald
  • Unit for Reproductive Medicine-Clinic for Horses University of Veterinary Medicine Hanover, Foundation, Hanover, Germany.

MeSH Terms

  • Horses
  • Pregnancy
  • Female
  • Animals
  • Retrospective Studies
  • Pregnancy Reduction, Multifetal / veterinary
  • Pregnancy Outcome / veterinary
  • Ultrasonography, Interventional / veterinary
  • Ultrasonography, Interventional / methods

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