The first question most mare owners ask is, ” Will the ICSI procedure damage my mares ovaries?”

That was the first concern I had when I started performing this procedure in 2006.  We first learned to aspirate follicles on recipient mares, which was all we did for 2 years.  First we were aspirating mature follicles through the flank approach, with a trocar and needle through a surgically prep on the donors flank.  The needle was introduced into the follicle without ultrasound guidance.  With that procedure, I worried about damaging the ovary with the needle, accidentally puncturing the bowel or other organ, infection or hemorrhage.  After about 300 of those procedures, the only problem we had was 2 abcesses in the abdominal wall where the trocar was introduced.  After modifying the procedure to inject penicillin into the trocar tract after the aspiration, no more abcesses occurred.  I ultrasounded the donors the following day, I was worried about hemorrhage. There was never more hemorrhage than occurred with a hemorrhagic ovulation.

Then we began ultrasound guided aspiration of small follicles through the anterior vagina with an aspiration probe and a long needle.  This approach allowed us to enter the ovary from the medial surface,  which is much safer because the oviduct is located on the lateral side.  A concern was that the aspiration needle would penetrate the oviduct causing blockage from scar tissue, but this cannot happen with the vaginal approach because the oviduct is on the far side of the ovary.  The next concern is actual damage to the ovary from repeated penetration of the aspiration needle, both during one session (can be 3 to 5 actual needle entry points depending on the number and location of the follicles in the ovary), and the accumulated damage from repeated aspirations over time.  The following article was published in 2005, investigating that question and finding no negative effects on fertility.  The next article was published in 2015 with similar results.

Volume 88, Issues 3–4, September 2005, Pages 299–30

 Fertility in the mare after repeated transvaginal ultrasound-guided aspirations

“Seventy-six TUGAs were carried out on 20 mares during the breeding season; 153 follicles were aspirated and 31 oocytes were recovered (20.3% per follicle; 40.8% per TUGA attempt). Of the 76 aspirations, 52 were carried out during estrus and 24 in diestrus.  Of the 20 mares involved in this study, 10 were artificially inseminated with fresh semen from a single fertile stallion at the first spontaneous heat following the previous aspiration. Of the 10 inseminated mares, 7 were found to be pregnant 16, 30 and 50 days after artificial insemination (AI), indicating that repeated TUGAs did not adversely affect fertility.”


Available online 24 November 2015

In Press, Corrected ProofNote to users

Evaluation of diagnostic utility, safety considerations, and effect on fertility of transvaginal ultrasound-guided ovarian biopsy in mares

The aim of this study was to determine the effects on health and fertility of TVLB and TVOB in mares; 53 mares were included in the study (11 control non-biopsied mares, 37 TVLB mares biopsied on one or more of the following Days 8, 10, 12, 15, 21, and 5 TVOB mares with ovarian abnormalities), resulting in a total of 108 TVLB and TVOB cycles and 183 procedures. Fertility was not significantly different in control and TVLB Groups 1 to 3 (P = 0.7648) and in the first or subsequent cycles where the ovulation was from an ovary that had a previous TVLB (P = 0.7147). A TVLB on Day 8 post-ovulation may induce an early return to estrus. In conclusion, the TVLB or TVOB procedure had no effect on health and fertility in this study if the procedure was correctly performed with good technique.

Other research has studied the effects on multiple needle puncture on the microscopic lesions in the ovary.  Because the ovary is so vascular and the needle tracts are so small relative to the size of the ovary, no lesions were found on microscopic examination.  The following are examples of mares on which we have performed multiple procedures and then bred to carry or to flush embryos:
Client #1- 16 follicle aspirations the last two years – since has produced embryos
Client #2- 38 aspirations over 4 years – last year produced 2 embryos
Client#3- 14 aspirations over 2 years – pregnant herself this year
Client #4 – 4 aspirations – embryo last year
Client #5 – 4 aspirations – embryos last year
Client #6- 2 aspirations – embryo last year
Client #7 – 7 aspirations – embryos since
Client #8 – 2 aspirations – embryo last year
PLay Like Clay – 31 aspirations – Little Jazerrey embryo
Watch Chick Run – 27 aspirations – several embryos since
There are others but these are the most current examples. Play LIke Clay and Watch Chick Run belong to me and have many pregnant recipient mares from both ICSI and ET, frozen embryos and foals on the ground. Both are still being aspirated and flushed for embryos.

Based on our personal experience since 2006, after approximately 1400 aspirations, both through the flank and then with the transvaginal procedure,  we have seen no infected ovaries, no peritonitis, no excessive hemorrhage and very little pain. We keep all mares overnight and recommend 3 days rest before returning to training or competition.  We have performed this procedure on barrel racing mares, hunter-jumpers, 3 day eventers and Arabian show mares that have returned to competition with no negative effects.

Please contact us through the website contact page with any questions or concerns about the safety of the ICSI procedure.

Thank You,

Dr. Rick Beck