Weatherford Equine Oocyte Services

Weatherford Equine was the first reproductive center to offer oocyte services in the North TX area back in 2013. Since then Dr. Young has performed thousands of aspirations and is very experienced in providing for all the needs associated with collecting oocytes from mares to undergo ICSI fertilization. He can perform pre-ovulatory aspirations, immature aspirations, or post mortem collections.

Mares can be managed at our facility or on a haul in basis. We also work closely with referring veterinarians that may wish to manage the mares and ensure the mares are prepared for a scheduled outpatient aspiration.

We have strong working relationships with the top ICSI labs in the country and can assist in coordinating semen delivery to be used to inject the oocytes.

We also work closely with the ICSI labs to coordinate shipping embryos back to Weatherford Equine for transfer, or to the recipient facility of the embryo owners choice, once the embryos are ready.

Weatherford Equine’s ultimate goal is to work with both mare owners and stallion owners to maximize the number of live foals conceived via ICSI.


  • First to offer oocyte aspirations in North TX (est. 2013)
  • Over 2,500 successful/safe aspirations performed to date
  • Strong working relationships with the top equine ICSI labs in the country.

Reasons to Pursue ICSI

Stallions with limited availability of semen* or stallions with low quality semen

Mares that are no longer able to produce embryos via traditional methods

Unexpected death of a mare

Overview of the Process for Utilizing ICSI

The first step of the ICSI procedure is to recover oocytes from the mare. The oocytes are recovered by transvaginal follicular aspiration (TVA). In this procedure, using ultrasound guidance, a needle is used to aspirate follicles present on the ovary. The procedure is performed with the mare standing in the stocks under sedation and takes 15-60 minutes depending on how many follicles are being aspirated. This can be done as an outpatient procedure.

ICSI procedure (injection of a sperm cell into an oocyte)

Once the oocytes have been collected they are carefully processed, packaged and sent to a reputable equine ICSI lab for fertilization.

The next step occurs at the ICSI lab and requires a small amount of semen that can be fresh or frozen depending on availability. This is when the actual ICSI takes place. ICSI stands for Intra-Cytoplasmic Sperm Injection and is performed by injecting a single sperm cell directly into the mares oocyte. The fertilized egg is then cultured in the lab until it becomes a transferable embryo.

Once a healthy embryo has been cultured at the laboratory (process takes 7-10 days) the resulting embryos will need to be implanted into recipient mares.  We work closely with the ICSI labs to coordinate shipping them back to Weatherford Equine for transfer, or to the recipient facility of your choice. If ICSI is performed in the off season, or if excess embryos develop, the embryos can be vitrified and the shipping is coordinated at a later time.

Overview of the Process for Utilizing ICSI

Mature oocyte

Immature oocytes

Pre-Ovulatory (Mature) Aspiration: A large dominant follicle is aspirated right before the mare ovulates in her cycle.

  • This method allows the mare to “mature” the oocyte in a natural setting, her body
  • These oocytes typically have a higher likelihood of becoming a transferable embryo (~40%) but there is typically only one dominant follicle to aspirate per session
  • This can be done every time the mare cycles, approximately every 14 days but does require that she be cycling

Immature Aspiration: All the follicles present on the mare’s ovary are aspirated regardless of where she is at in her cycle

  •  The immature oocytes require further maturation in the lab. Then, once mature (~65% of the oocytes collected), the oocyte is fertilized similarly to a mature pre-ovulatory oocyte
  • These oocytes don’t have as high of likelihood of becoming transferable embryos (~20%), but typical immature aspiration sessions at Weatherford Equine will yield an average of 8 immature oocytes
  • This approach can potentially be done every 14 days and the mare does not have to be cycling, she only needs to have multiple follicles present, sometimes it is beneficial to wait longer between sessions          to allow more follicles to develop

Statistically speaking there is a much higher chance of achieving pregnancies via the immature aspirations but this is dependent on the mare having a large number of follicles. Some mares may not be good candidates for immature aspiration and can only be done using the pre-ovulatory method.

In 2014, of oocytes done at Texas A&M ICSI laboratory, there was an overall average of one blastocyst produced per immature aspiration session.

*Every donor mare is different and results can vary considerably*

Combination Aspiration: In the event there are a large number of small follicles present at the same time as a large dominant follicle both the Immature and Pre-ovulatory aspirations can be performed at the same time allowing the benefits of both.*
*This will require two separate ICSI sessions and will be billed as two separate charges.

Overview of the Process for Utilizing ICSI







1877 Mineral Wells Hwy,
Weatherford, TX 76088

office: 817.594.9100
fax: 817.596.5770 email:hospital@weatherfordequine.com


6375 Mineral Wells Hwy,
Weatherford, TX 76088

office: 817.594.9181
fax: 817.594.9183 email:breeding@weatherfordequine.com