12th Mar 2019
Mares that have a foal at foot are known as wet mares. The mares first cycle after foaling typically occurs at around six to twelve days post foaling which is called a foal heat. Mares generally ovulate at around day 10 after foaling but this can vary. We start teasing a wet mare at 6 days post foaling. We tease her with a small stallion pony called a teaser. At around day 8 or 9 the vet will examine the mare and take a cervical swab. This swab will determine if the mare is clean or dirty (has an infection) after foaling. Once the swab is taken, it takes 24 hours to get the results back. If the mare is clean she can be covered by a stallion on foal heat. However, if a mare is dirty she will need to be treated with intrauterine antibiotics. Depending on the growth of the swab, this will determine how many days she is treated for.
We work closely with the vets to ensure we are covering the mare close to ovulation. Mares usually ovulate around day 10 but some could ovulate as early as day 7 or as late as day 13.
The mare will be scanned at two days after cover to check for ovulation. We do this because the stallion’s sperm usually lasts for approximately 48 hours. If the mare hasn’t ovulated she will be covered again. This is known as a cross cover.
Once a mare is covered and has ovulated, she will have her first scan at 14 days to check for pregnancy. She has a second scan at 16 days to determine if the mare has twins. Twins can often occur in a mare when two of her follicles ovulate and both eggs become fertilized, resulting in two embryos. Unfortunately horses are not designed to carry and produce twins. A twin pregnancy puts both the mare and foals at risk and a good outcome is very rare. In the case of twins, the vet will pinch the smaller or unhealthy looking one.
The vet scans the mare again at 30 days. At as soon as 30 days you can see the heartbeat clearly flicker. The mare is scanned again at 42 days to ensure the pregnancy is healthy. Her final scan is at 60 days, which is when the vet is able to tell the sex of the foetus.
If the mare is not covered at foal heat she can be covered on her second cycle. This starts at around day 24 until around day 33. They are usually covered between day 29 and 31.
The gestation of a mare is usually between 320 and 362 days. However, most mares foal within 330 to 345 days.
Laura Bennett, Kildare Yard Foreman.