Evaluation of pregnancy and foaling rates after reduction of twin pregnancy via transvaginal ultrasound-guided aspiration in mares.

This research assessed the effectiveness of twin pregnancy reduction through transvaginal ultrasound-guided aspiration (TUA) in mares, focusing on subsequent pregnancy and live foaling rates as well as the influence of gestational periods and other TUA-related factors. Results showed TUA as an effective method for reducing twin pregnancy, with the highest success before gestational day 43.

Study Methodology

• The study took the form of a clinical trial involving 44 mares pregnant with twins. Their gestational periods ranged from 25 to 62 days.
• All mares underwent TUA, with embryonic or fetal puncture combined with TUA in 13 cases.
• Follow-up ultrasonographic examinations were done by referring veterinarians.
• The study then evaluated the effects of gestational period and other TUA-related factors on pregnancy and foaling rates.

Study Findings

• Singleton pregnancy, persistent twin pregnancy or the loss of both conceptuses was confirmed 5 to 7 days after TUA.
• Two mares experiencing persistent twin pregnancy underwent another TUA, while one underwent prostaglandin F(2α)-induced abortion. These cases were excluded from subsequent analyses.
• Three to four weeks following TUA, 18 out of 24 re-evaluated mares were found to be pregnant with a single conceptus.
• Twenty out of the original 41 mares delivered a live singleton foal, representing a 49% live foaling rate.
• The gestational period during which TUA was performed didn’t significantly affect early pregnancy rates.
• The foaling rate was significantly lower for mares that underwent TUA after day 42 (0/5) compared to those that underwent TUA between days 31 and 35 (9/14).
• Three out of thirteen mares that underwent TUA combined with embryonic or fetal puncture delivered live foals, compared to 17 out of 28 who only underwent TUA.
• No significant effects were found from other TUA-related variables.

Conclusion

• The study concludes that TUA was an effective method for reducing twin pregnancy in mares. The process yielded the best results when conducted before the 43rd day of gestation.