Efficacy of transvaginal ultrasound-guided twin reduction in the mare by embryonic or fetal stabbing compared with yolk sac or allantoic fluid aspiration.

The research study investigates the efficacy of different methods for transvaginal ultrasound-guided pregnancy reduction (TUGR) in horses, particularly when managing twins after fixation. The study reveals no significant advantage of fetal stabbing over fluid aspiration, but advises performing TUGR before day 35 of gestation as it presents a better probability of success.

Transvaginal Ultrasound-Guided Pregnancy Reduction (TUGR)

• Transvaginal ultrasound-guided pregnancy reduction is a procedure employed in the management of twin pregnancies in horses, especially after fixation. However, success rates for this intervention are often low.
• Twin pregnancies in horses can lead to complications, often resulting in miscarriage or the birth of undersized foals. This is where TUGR is effective, reducing the pregnancy to manage these challenges.

Comparing Efficacy of Method: Fetal Stabbing vs Fluid Aspiration

• The study scrutinized the data from 103 TUGR interventions, aiming to determine whether stabbing the embryo/fetus was any better than aspirating conceptus fluids.
• Success was measured by the birth of a healthy, single foal. The data did not show any significant difference in birth outcomes between fetal stabbing and fluid aspiration techniques.

Influence of Gestation Stage and Location of Conceptus on success

• Relative conceptus location (i.e., uni- vs. bilateral), stage of gestation, and treatment method were considered interdependent factors that possibly influence the outcome of TUGR.
• The study found that neither the location of conception (whether unilateral or bilateral) nor the intervention method had significant influence on the outcome.
• However, it was noted that TUGR was numerically more successful when performed at or before Day 35 of gestation as opposed to after Day 35.

Time Constraints and Risks

• The study suggests that Day 45 may be a critical threshold as TUGR interventions beyond this day yielded far less successful outcomes. Therefore, it was concluded that TUGR is not the preferred method for reducing twins beyond Day 45 of gestation.
• Despite four recorded pregnancy losses 1 to 7 months post-TUGR, the researchers did not firmly attribute these to the procedure itself due to this being a normal rate of late gestation pregnancy loss.

Conclusion from the Study

• The study concluded that TUGR by fetal stabbing does not offer any significant advantages over fluid aspiration.
• The research recommends that TUGR should be performed before Day 35 of gestation. It also describes TUGR as a salvage procedure, advisory when re-breeding is not a feasible alternative resort for the management of twins in horses.