Foal born using intracytoplasmic sperm injection to a Friesian mare with unexplained subfertility

Intracytoplasmic sperm injection (ICSI) is an advanced reproductive technology wherein oocytes are retrieved from tertiary follicles and injected with a single sperm to develop into an embryo in vitro. Unlike embryo transfer, ICSI affords versatility for mares with a suboptimum uterine environment, blocked oviducts, or at postmortem where the opportunity for natural fertilization is not possible. ICSI can also be used when limited numbers of poor-quality sperm are available. 1 This technique provides the possibility to obtain foals from mares that otherwise could not propagate their genetics. A 13 year old Friesian mare presented to the UC Davis Theriogenology service in May 2013 for breeding with cooled semen after several years of unexplained subfertility. Uterine cytology was taken at multiple intervals, with no clear evidence of endometritis. On ultrasonography, anechoic fluid was present in the uterus after all breeding attempts. Treatments included uterine lavages and oxytocin to enhance uterine clearance. In 2016, after several unsuccessful breeding cycles, laparoscopic application of prostaglandin E 2 in the oviducts was performed, with the suspicion that they could be blocked. 2 After the procedure, there were 2 more years of unsuccessful breeding attempts. In 2018, it was decided that this mare was an ideal candidate for oocyte retrieval and ICSI. In May 2018, transvaginal aspiration of oocytes was performed, where 15 follicles between 10 - 30 mm were aspirated from both ovaries. Of the 15 follicles aspirated, 9 oocytes were recovered. Four of these oocytes matured to the MII stage in vitro and underwent ICSI. Two embryos matured and were shipped as blastocysts to Colorado State University where they were implanted into 2 recipient mares. Both embryos survived until fetal heartbeats were detectable, with 1 pregnancy surviving to term. The 7 year old recipient mare was transported to UC Davis where she foaled successfully and without complications.

Keywords: Equine, intracytoplasmic sperm injection, mare subfertility

References

1. Colleoni S, Barbacini S, Necchi D, et al: Application of ovum pick-up, intracytoplasmic sperm injection and embryo culture in equine practice. Proc Am Assoc Equine Pract 2007;53:554-559.
2. Allen WR, Wilsher S, Morris L, et al: Laparoscopic application of PGE2 to re-establish oviducal patency and fertility in infertile mares: a preliminary study. Equine Vet J 2006;38:454-459.

This manuscript was originally published in the journal Clinical Theriogenology Vol 12(3) Sept 2020.  Clinical Theriogenology is the official journal of the Society for Theriogenology (SFT) and the American College of Theriogenologists (ACT).  This content has been reproduced on the IVIS website with the explicit permission of the SFT/ACT.