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Equine Insemination Protocols

Pre and Post Protocols for Mares


  • Examine mare once daily until a 35 mm follicle is present
  • Continue to monitor follicle, injection of hCG or GnRH optional
  • Palpate at six hour intervals
  • Inseminate within six hours post-ovulation


  • Examine mare once daily until a 35 mm or larger follicle is present
  • Give hCG or GnRH
  • 24hours post-injection, begin twice daily palpations
  • Inseminate with ½ dose 24 hours post-injection
  • Inseminate with ½ dose within six hours post-ovulation


  • Examine mare once daily until a 35 mm pre-ovulatory follicle is present
  • Administer hCG or GnRH
  • Inseminate with one dose at 24 hours post-ovulating agent
  • Inseminate with one dose at 40 hours post ovulating agent


  • A relatively new method of inseminating with frozen semen that uses fewer numbers of sperm, deposited at the uterotubal junction. Deep uterine insemination increases conception rates when used with low-dose insemination (such as when using sex-sorted semen) and with sub-fertile semen. However, when this method is used with doses containing high numbers of good quality sperm, a reduced conception rate results. The deep uterine technique may be used with all of the above protocols.


  • Post-breeding endometritis occurs in 20% of mares. If a uterine lavage is recommend because of endometritis, allow at least four hours after insemination before the lavage, to give sperm time to reach the oviduct.


  • Prepare the mare’s perineal area aseptically.
  • Prepare a constant temperature bath at proper temperature.
  • Remove straws from nitrogen container with a long hemostat or tweezers and quickly place in water bath, exposing semen to room temperature for no more than 2 or 3 seconds.
  • Leave straws in water bath as per thawing instructions.
  • Dry off the straws completely.  Water is spermicidal.
  • Hold straw vertically so that the air bubble is positioned on top of the straw and cut off the round sealing ball or other sealed end.
  • Place open end of straw over a sterile, pre-warmed 37 degree C container and cut off the other end of the straw allowing the extended semen to empty into the sterile container, or, use a Minitube device.
  • The extended semen is then inseminated just as with fresh semen.
  • Use entire insemination dose for optimal results.
  • Ideally the mare is inseminated within six hours of ovulation.  It is very strongly recommended that the mare be palpated and ultrasounded at least every twelve hours, when ovulation is close at hand.
  • Timing is everything. Your mare’s follicle must be monitored every few hours when she‘s close to ovulation. Though it was once common practice to inseminate before ovulation, or both before and after, many veterinarians now prefer to inseminate post-ovulation. It is believed that insemination within six hours after ovulation produces the best results, but some have had success inseminating up to eight or ten hours post-ovulation.
  • Some veterinarians use the timed insemination protocol, which involves fewer ultrasounds, but requires two inseminations per cycle, and thus more semen may be required.