Evaluation of pregnancy and foaling rates after reduction of twin pregnancy via transvaginal ultrasound-guided aspiration in mares.
OBJECTIVE
To assess pregnancy and live foaling rates after reduction of twin pregnancy via transvaginal ultrasound-guided aspiration (TUA) in mares and evaluate effects of gestational period, localization of conceptuses, fluid aspiration volume, and combination of TUA with embryonic or fetal puncture on these outcomes.


METHODS
Clinical trial.


METHODS
44 mares pregnant with twins (25 to 62 days of gestation).


METHODS
TUA was performed in all mares and combined with embryonic or fetal puncture in 13. Follow-up ultrasonographic examinations were performed by referring veterinarians. Effects of gestational period and TUA-related variables on pregnancy and foaling rates were assessed.


RESULTS
Singleton pregnancy (32/44 [73%]), persistent twin pregnancy (3/44 [7%]), or loss of both conceptuses (9/44 [20%]) was confirmed 5 to 7 days after TUA. Two mares with persistent twin pregnancy underwent another TUA, and 1 underwent prostaglandin F(2α)-induced abortion; these were excluded from subsequent analyses. Eighteen of 24 mares reevaluated 3 to 4 weeks after TUA were pregnant with 1 conceptus. Twenty of 41 (49%) mares delivered live singleton foals. Gestational period of TUA did not affect early pregnancy rates. Foaling rate for mares that underwent TUA after day 42 (0/5) was lowest of all groups and was significantly lower than that of mares that underwent TUA between days 31 and 35 (9/14). Three of 13 mares that underwent TUA with embryonic or fetal puncture delivered live foals, compared with 17 of 28 that underwent TUA alone. Effects of other variables were nonsignificant.


CONCLUSIONS
TUA was effective for reduction of twin pregnancy in mares, with best results achieved before gestational day 43.
Unit for Reproductive Medicine, Clinic for Horses, University of Veterinary Medicine, Hannover, 30559 Hannover, Germany.
Jutta
J
Klewitz
Natali
N
Krekeler
Florian
F
Ortgies
Antje
A
Heberling
Corinna
C
Linke
Harald
H
Sieme
D000818:Animals; D005260:Female; D006736:Horses / Q000502:physiology*; D011183:Postoperative Complications / Q000662:veterinary; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000662:veterinary; D018607:Pregnancy Reduction, Multifetal / Q000379:methods / Q000662:veterinary*; D011270:Pregnancy, Animal