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How to bring your mare into Oestrus

How to bring your mare into Oestrus


Non Pregnant mares: Ultrasound scan for ovary and uterine evaluation to identify where in her cycle she is and if any uterine pathology exists ie, uterine cysts, uterine fluid, ovarian abnormalities.

  1. Give the mare a prostaglandin injection and scan 2-3 days later.
  2. Give the mare oral progesterone for 10 days then a prostaglandin injection and scan 2-3 days later.
  3. Allow her to come into heat naturally.


Foaling mares: Your mare should be checked by the vet 9 days after foaling to make sure her uterus is clean and returning to its normal size.
Unless it is late in the season or your mare is young and has a very clean uterus, then normally we do not recommend using artificial insemination in mares during foal heat.
Therefore, allow your mare to have a foal heat and 7 days after the end of foal heat organise for your vet to treat her with prostaglandin /PG. Three days after her injection she can be scanned.

Insemination procedures


Natural mating: We can manage your mare’s oestrous cycle so that you can organise the optimal time to take her to the stallion for natural mating. In these situations it is ideal if we evaluate your mare after mating as well to rule out any problems with uterine infection or ovulation.

Fresh / chilled semen Al: The management of the mare’s oestrous cycle for artificial insemination is similar to that for natural mating. We normally ultrasound scan your mare 4 -10 times per oestrous cycle to optimise the timing for ordering the semen inseminating the mare and to rule out post breeding infections.

Frozen semen: The lifespan of frozen semen is usually only 6- 12h after thawing. Therefore we scan your mare multiple times and often throughout the night to make sure that we inseminate your mare within 6 hours after she ovulates. For each insemination we evaluate every sample of semen very carefully and can manage your mare’s programme to optimise the semen quality.


Pregnancy diagnosis

It is very important that mares are scanned by ultrasound at 15 and 21 days after ovulation to ensure that they are pregnant and to rule out twins. If twins are diagnosed at this stage they can be treated successfully in 90% of cases. Normally, most pregnancy loss occurs between 20 and 30 days so we also recommend that a pregnancy scan be performed every 10 days until she is 45 days pregnant.